© CSIRO Entomology, 2003 This work is copyright. Apart from any permitted use under the Copyright Act 1968, no part may be reproduced without prior permission from CSIRO. All requests should be addressed to: The Chief CSIRO Entomology, GPO Box 1700, Canberra, ACT 2601, Australia
Citation: Colloff, M.J., Fokstuen, G. and Boland, T. (2003) Toward the Triple Bottom Line in Sustainable Horticulture: Biodiversity, Ecosystem Services and an Environmental Management System for Citrus Orchards in the Riverland of South Australia. CSIRO Entomology, Canberra.
TOWARD THE TRIPLE BOTTOM LINE IN SUSTAINABLE HORTICULTURE: BIODIVERSITY, ECOSYSTEM SERVICES AND AN ENVIRONMENTAL MANAGEMENT SYSTEM FOR CITRUS ORCHARDS IN THE RIVERLAND OF SOUTH AUSTRALIA
Matt Colloff1 , Geir Fokstuen1 and Tamara Boland 2
CSIRO Entomology, GPO Box 1700, Canberra, ACT 2601; [email protected]
2 Australian Landscape Trust, Calperum Station, PO Box 955, Renmark, SA 5341
CSIRO does not make any warranties and does not accept any liabilities for any loss or damage resulting from the use and/or reliance upon the information, advice, data and/or calculations provided in this report.
CONTENTS Acknowledgements Executive Summary Chapter 1, Introduction 1.1 Background 1.2 The Riverland of South Australia 1.3 Citrus Growing in the Riverland 1.4 Project Design 1.5 Project Organization and the Roles of the Participants Chapter 2 Ecologically Sustainable Agriculture 2.1 Biodiversity Drives Ecosystem Processes 2.2 Ecosystem Goods and Services 2.3 Modern Conventional Agriculture 2.4 Structural Complexity Facilitates Biodiversity 2.5 Biodiversity as a Resource for Farmers 2.6 Sustainable Agriculture – Defining Principles
2.7 Environmental Management Systems Chapter 3 Farm Inputs and Outputs 3.1 Introduction 3.2 Inputs and Outputs in Riverland Citrus Production 3.3 Nutrient Inputs and Outputs 3.4 Dollar- and Energy Value of Inputs and Outputs Chapter 4 Soil Physical and Chemical Properties 4.1 Introduction – the Soils of the Riverland Region 4.2 Methods 4.3 Results 4.4 Discussion Chapter 5 Soil Biology: Nutrient Cycling as an Ecosystem Service 5.1 Introduction 5.2 Nematodes 5.3 Arthropods 5.4 Management of Soil Biodiversity as a Resource Chapter 6. Natural Enemies of Kelly’s Citrus Thrips: Pest Control as an Ecosystem Service 6.1 The Problem - Kelly’s Citrus Thrips 6.2 Methods 6.3 Results 6.4 Discussion - Management of Natural Enemies and Conservation Biocontrol Chapter 7. Conclusions and Recommendations References Appendices
Appendix 1. Elemental Nutrient Content of Foliar Spray and Fertiliser Inputs (kg ha yr) Appendix 2. Inputs (kg ha yr) Converted to Energy Input Values (MJ ha yr) Appendix 3. Production Energy Values of Different Inputs Appendix 4. Costs of Inputs ($) Appendix 5. Calculation of Nutrient and Energy Content of Crop and of Organic Fertiliser Inputs Appendix 6. Methods of Preparation of Soil Samples Prior to Analysis Appendix 7. Key to Some Soil-inhabiting Mesostigmata from Citrus Orchards Appendix 8. Manual of Best Practice and Audit Sheet for Ecologically Sustainable Citrus Production
ACKNOWLEDGEMENTS This Project was funded by the Natural Heritage Trust; Department of Environment and Heritage, Government of South Australia; the Murray Darling Basin Commission and the River Murray Catchment Water Management Board. This project would not have been possible without the commitment of the Riverland Citrus Growers and members of the Citrus Sustainability Group, in particular James Altman, Ian Armstrong, Chris Barry, Grant Brown, Tracy Codd, Steve Gibbs, Matt Goodwin, Humphrey Howie, David Ingerson, Ian King, Darryl Lang, Shane Phillips, Mick and Tania Puntierio and Trevor Ziersch. We thank the staff and Volunteers of Australian Landscape Trust for logistical, operational and administrative support, especially Deborah Bogenhuber, Patricia Feilman, the late Jelena Mastilovic, and Lesley Vink. Several colleagues made significant and valuable contributions to this project: Jo Cardale, Geoff Clarke, Bruce Halliday, Joanna Hamilton, Mike Hodda, Laurence Mound, Ian Naumann, Olga and Stefan Schmidt, David Walter, and Saul Cunningham who we thank especially for reviewing the manuscript and for his constructive criticism. We thank Paul Dalby, then of the University of Adelaide, for his involvement in the early phases of this project and Graham Broughton, previously of the River Murray Catchment Water Management Board, for his interest and support. Finally, we thank Pamela Parker, Chicago Zoological Society, for her commitment, dedication, enthusiasm, kindness, companionship, endless hospitality and for her tireless championing of this project from start to finish.
EXECUTIVE SUMMARY This project represents work arising as part of the Natural Heritage Trust- funded Community Project, “Monitoring in Pursuit of Ecologically Sustainable Development and Best Practice” (NHT Murray-Darling 2001 Program). It comprises the agro-ecological component of a larger activity on sustainability and best practice in the Riverland citrus industry. The purpose of this component is to provide the scientific basis to underpin the development of an environmental management system (EMS) and code of best management practice (BMP) by citrus growers. The adoption, implementation, accreditation and marketing of the code of best practice form a related but separate activity. The project is a collaboration between citrus growers, CSIRO scientists and staff of Australian Landscape Trust. One objective was to develop a learning partnership between scientists and growers, in order that growers had some ownership, control, and intellectual input to the scientific aspects of the study, with the intention of increasing the likelihood of adoption and uptake of the research outcomes. One of the required outcomes was for indicators of ecological sustainability, with a focus on soils. Another was for data that led to an understanding of key ecosystem services, such as nutrient cycling and pest control. This necessitated a baseline survey of the biodiversity of soils in a range of citrus orchards that were representative of different generic management practices in the Riverland. Four types were chosen, with two properties in each category: organic, pesticide- free, conventional and high-tech. Quantitative monitoring of soil invertebrate populations was conducted quarterly from August 1998 to August 1999 on the 8 properties within the area between Waikerie, Loxton and Paringa. This sampling regime allowed us to detect seasonal variation in population densities. We conducted for each property a simple, comparative input-output analysis of water, nutrients, energy and dollar value of production costs and revenues for the year 1999/2000. This provided some important insights into the value of these economic and environmental parameters as indicators of sustainability. We found that there is considerable flexibility within citrus production systems towards achieving ecological and economic sustainability. Enterprises have specific priorities and varying degrees of flexibility, dependent on the constraints of existing production methods and ethos, business plans and financial status and willingness to adopt new practices. There can be no ‘one size fits all’ strategy for adoption of sustainable production, only a pick-list of guidelines and options. The selection of a particular approach will contain a careful, considered balance between benefits to the enterprise and to the broader environment. Achieving improvement s to one at the expense of the other is not sustainability. In relation to nutrient cycling, the data from the baseline survey allowed us to construct the basic food web of key functional groups of organisms and to estimate the relative impact of these groups on soil nutrient cycling. Furthermore, we estimated the value of the total soil invertebrate population in terms of the dollar value of nitrogen per hectare contained within it. We found that there was an average variation between properties over the four sampling periods of $33 to $2 per hectare (range $76 to $1), giving us a useful insight into the variation between properties in relative soil invertebrate biomass and its capacity to provide nitrogen to the soil when that biomass died and decomposed. We found a strong positive relationship between soil invertebrate biomass and soil carbon and a weaker correlation with soil nitrogen and phosphorous levels. There was no relationship between soil invertebrate biomass and the type of generic management practice of the orchards.
At the end of the first year of monitoring, the citrus growers were asked to define their priorities for research in Year 2. They agreed that a major issue that required investigation was the ecology and biology of the major pest, Kelly’s Citrus Thrips (Pezothrips kellyanus). Four growers reported that Kelly’s Citrus Thrips was a significant cause of economic damage in their orchards, and the other four reported that it was not. We then analysed the data we had gathered during Year 1, in a retrospective study of possible factors associated with the presence of Kelly’s Citrus Thrips as a major pest. The first factor we found was that growers for whom Kelly’s Citrus Thrips was not a significant problem had far greater population densities of mites in their orchards, especially during August 1998. We re-examined the mite data and found that there was a high representation of predatory mesostigmatid mites. We developed a pictorial identification key and found there were at least 17 species present in the orchards. By collating information on the known biology and feeding habits of these predatory mites, we were able to deduce that many of them were generalist predators that would be capable of feeding on thrips larvae which fall from the trees to the soil in order to pupate. The second factor we found was that the orchards where Kelly’s Citrus Thrips was not a significant problem had dense ground cover consisting of diverse perennial grasses and herbs. In orchards where significant economic damage occurred, ground cover was either partially absent, or dominated by a combination of annual weeds or an inter-row monoculture such as Lucerne or Oats. We formulated the hypothesis that the absence of economic damage by Kelly’s Citrus Thrips was related to the presence of an abundant and diverse fauna of natural enemies in the form of predatory mites, which was enhanced by the availability of good quality habitat in the form of perennial ground cover. As a result of these findings, the Horticulture Research and Development Corporation (HRDC) provided funding in July 2000 to the South Australian Research and Development Institute (SARDI), who have been engaged since 1997 in research on the integrated pest management of Kelly’s Citrus Thrips, for further research on the role of predatory mites in the conservation biocontrol of Kelly’s Citrus Thrips. We are collaborating with SARDI on this project. We have investigated two key ecosystem services of economic value to citrus growers pest control and nutrient cycling. Both of these ecosystem services are delivered by components of soil biodiversity. We have found that the factors associated with enhanced capacity to deliver these ecosystem services are not associated with the generic management practice of each orchard, but with specific management practices such as: •
maintenance of ground cover of perennial grasses and herbs in order to provide good habitat quality for natural enemies of pests;
use of ground cover as a source of nutrients and as a means of soil water conservation through slashing and mulching;
use of fertiliser regimes and nutrient management programs that depend on decomposition of organic carbon and nitrogen, rather than direct uptake of inorganic, plant-available forms;
relatively low inputs of inorganic fertilisers, pesticides and heavy metals.
We suggest that these specific management practices be regarded as current recommended best practices and incorporated into the code of best practice that is being developed and accredited by the growers.
Chapter 1. INTRODUCTION 1.1 Background This project represents a partnership between CSIRO Entomology, a group of citrus growers in the Riverland of South Australia and staff of Australian Landscape Trust based at Bookmark Biosphere Reserve, Renmark, South Australia. Bookmark Biosphere Reserve is part of the UNESCO Man and the Biosphere Program, which seeks sustainability and integration of communities, biodiversity and the health and wellbeing of landscapes and water resources. The Australian Landscape Trust was founded by the Ian Potter Foundation to pursue strategic programs in the areas of environment and sustainability. The ALT is a partnership of several philanthropic foundations formed to invigorate community efforts to find sustainable ways of living within Australia's unique landscapes. A central objective of the ALT is to forge partnerships between public and private sector institutions that are motivated by the desire to conserve and restore Australia's biodiversity. By supporting community attempts to implement solutions to regional environmental degradation, the ALT believes it can enhance Australia's biological and cultural well-being. The programs of the Bookmark Biosphere Reserve in the Riverland of South Australia and the recent Gippsland Red Gum Plains Restoration Project are the tangible manifestations of this vision. The project provides a framework for the aspirations of Riverland communities to invest in quality of life for future generations and to explore and develop sustainable methods of land use within an established industry in the Riverland community, citrus production, as a model for understanding the linkages between best practice (BP) and ecologically sustainable development (ESD) at the industry and property levels. The citrus industry represents a significant form of land use on the floodplain in the Riverland region, with impacts on biodiversity and water quality. Representatives of the citrus industry have embraced this project as an opportunity to develop a prototype BP accreditation scheme for the industry as a means of further promoting ESD. Scientists and industry representatives have together identified citrus operations using different practices with varying impact on environmental conditions. The original terms of reference for the project were: “The project will identify and assess the condition of biodiversity indicators at various sites under different conditions of management. Based on the results of this work, the project will develop a set of tools for use in monitoring the condition of existing citrus operations and assessing long-term sustainability. The project will also explore the connection between biodiversity in soil fauna and productivity. The expected outcome of the project will be to help promote BP by demonstrating an improvement in the efficiency and environmental impact of citrus operations. Once developed, the techniques of monitoring, establishing BP and using it for marketing purposes will be shared more broadly in the citrus industry and related industries in the floodplain. Applications to other land uses on other landforms will be explored and promoted through public education as part of the overall Bookmark Biosphere Program.” 1.2 The Riverland of South Australia The Riverland is the area located on either side of the Murray River, extending from the New South Wales border in the East to Waikerie in the West (Fig. 1.1). The region is one of the most important areas of irrigated horticultural production in Australia, producing wine and table grapes, citrus, peaches, apricots, vegetables and almonds. Some of Australia’s largest food and wine producers have significant operations based in the Riverland, including Southcorp, BRL Hardy and Berri Ltd. Minor but growing horticultural industries include
olives, pistachio nuts, cherries, apples, avocadoes and floriculture. The tourism sector provides a significant source of employment. The population of about 34,000 is based in the major river towns of Barmera, Berri, Loxton, Paringa, Renmark and Waikerie. The Riverland grows 50 per cent of the South Australia’s wine grapes, making it Australia's largest wineproducing region.
Fig. 1.1 Map showing location of the Riverland of South Australia and Bookmark Biosphere Reserve. Source: Australian Landscape Trust. Details of the climate, vegetation, biodiversity, agriculture, human settlement and impact in the Riverland, with particular emphasis on Bookmark Biosphere Reserve, can be found in the publication by Milliken (1995). 1.3 Citrus Growing in the Riverland New South Wales grows approximately 35% of total Australian citrus output. South Australia follows with 33%, Victoria 20%, Queensland 10%, Western Australia 2% and a small but growing industry in the Northern Territory. There are approximately 3,000 citrus growers, cultivating about 10 million trees on 32,000 ha of land. The largest numbers of growers are situated in the Riverland region of South Australia. Of the nearly 1,000 citrus holdings in South Australia, 83% are 10 ha or less in size. In Australia, most citrus farms are mixed fruit growing operations and are relatively small; with the average area being harvested around 18 ha. Total Australian citrus production over the last 5 years has been gradually increasing from 513,000 tonnes in 1988-89 to 650,000 tonnes in 1999-00. This can be attributed to increases
in production of navel oranges and mandarins. Grapefruit, lemons and limes have seen a decrease in overall production. Citrus production in Australia first began in the 1890s when Renmark and Mildura were established as irrigation settlements and planted with Washington navel and Valencia orange trees from California. Establishment of fruit blocks by soldier-settlers after World War II had a major impact on citrus production (George, 1999). In South Australia, oranges (predominantly Navel and Valencia varieties) represent ca. 87% of production; lemons and limes 6%; mandarins 4%, grapefruit 2% and all other varieties, such as tangelos, 1%. The value of citrus production in 1996-97 was $110.2 m, compared with $298.3 for vine fruit, the other major irrigated horticultural crop, representing 5.3% and 14.4% of gross value of South Australian crops respectively (Australian Bureau of Statistics, 1999; 2000a). Citrus production in South Australia, although lower than New South Wales in terms of numbers of trees and total production, is by far the highest of the States and Territories in value of production, primarily due to the shift away from lower value production for juicing and domestic markets to higher value fresh fruit for export. Table 1.1 Citrus production data in Australia by State and Territory ('000 tonnes).
NSW VIC SA QLD WA NT Total
Navel Oranges 98/99 99/00 00/01 37 62 76 42 48 61 52 53 70 13 14 14 4 4 4 0 0 0 149 180 225
Valencia Oranges 98/99 99/00 00/01 115 153 159 66 60 58 106 110 145 10 9 10 4 4 4 0 0 0 299 335 375
Mandarins, Lemons Limes, Grapefruit 98/99 99/00 00/01 11 12 13 24 21 22 30 25 26 73 73 77 4 4 5 0.5 0.5 0.5 142.5 135.5 143.5
98/99 161 131 187 96 12 0.5 587
Total 99/00 224 129 188 95 12 0.5 648
00/01 247 142 240 100 13 0.5 742
Source: Australian Citrus Growers Inc. (2000): http://www.austcitrus.org.au 1.4 Project Design The project commenced in August, 1998 following discussions with the growers and Bookmark Biosphere reserve in January, 1998. There are two parts to the project: •
development and certification of a code of best practice, in order to provide the basis for an environmental management system for growing citrus sustainably;
definition and certification of what constitutes sustainable production. This latter part gives the code of best practice a scientific basis and is the part in which we are most heavily involved. All partners have participated in drafting the code of best practice, which focuses on: § § § § § §
water conservation; pest management; weed management; nutrient management; soil management; environmental objectives.
The intention was for CSIRO Entomology to gather empirical data on pest, nutrient and soil management in order to provide objective evidence for the management options that form the basis of the grower-owned and operated code of best practice (Fig. 1.2). 9
Production and Management Practices
Research and Monitoring
Code of Best Practice and EMS
Fig. 1.2 The cycle of adaptive management used in this project. The initial production system forms the basis for research and monitoring of the interaction between management practices and agroecosystem function. This provides data on improvements that can make the production system more ecologically and economically sustainable. These improvements are then incorporated into the Code of Best Practice for citrus production and implemented. The modified production system forms the basis for the next cycle of research and monitoring. 1.4.1 Aims and Objectives The biological questions we are addressing are: • does soil biological diversity influence plant productivity in citrus production systems? •
how do citrus production and soil management practices affect soil biological diversity?
can soil biodiversity be managed so as to reduce farm inputs in a move towards sustainable production?
1.4.2 Outputs •
models of soil nutrient dynamics using food webs;
comparison of the functional diversity of soil invertebrate fauna under different citrus management systems;
assessment of the interaction between management practices and seasonal influences on soil biodiversity in citrus orchards;
potential indicators of soil heath and sustainable production.
1.4.3 Outcomes Outcomes to be measured by:
1. the development of effective techniques for assaying sustainability based on appropriate measures of indicators species through collaboration of scientists and community industry practitioners. The ability of community members to identify indicator species and measure appropriate physical parame ters as a means of assessment will be an essential indicator of success. 2. The development of industry support of demonstrable sustainability, identification of appropriate indicators and physical characteristics associated with sustainable uses of land and water resources on land used in intensive development; 3. The broader acceptance within the citrus industry of using best practice as a means of promoting sustainability, increasing productivity, and potentially enhancing market value; 4. The application of the approaches employed in this project to investigate issues of ecologically sustainable development in other industries Monitoring the success of the project in the short term was to be the responsibility of the collaboration between citrus growers and scientists. Over the long term, maintenance of the results, and expanding the uses of the techniques, was to be the responsibility of the citrus industry group (Citrus Steering Committee; Fig. 1.3) that has formed under the auspices of the Bookmark Biosphere Reserve. A key objective of this group is the development of a best practice accreditation program, based on appropriate monitoring techniques. Ultimately the success of such an effort will be the best measure of the success of this project and may be the only long-term measure of sustainability in the industry. 1.4.4 Methods Eight properties were chosen for the study. The basis for the choice was to obtain a spectrum of different production methods representative of citrus growing in the Riverland. The management categories were as follows: •
Organic; no use of systemic chemical herbicides and insecticides or mineral fertilizers; major input is composted animal manure and plant residues;
Pesticide Free; no use of systemic insecticides; some minor spot-use of herbicides; reliance on biological control agents and mineral oils; use of foliar nutrient sprays;
Conventional; use of mineral fertilizers and synthetic pesticides, but without monitoring of irrigation water usage, pests or nutrient requirements;
High-tech.; intensive, controlled use of mineral fertilizers, synthetic pesticides; with systematic monitoring of pests, nutrients, water use and water table level.
Two properties belonging to each category were chosen for detailed study. They are located in triangle of land bordered by Waikerie in the west, Paringa in the east and Loxton to the south. Properties have been coded (eg. Conventional 1, Conventional 2, High-tech 1 etc.) to protect the privacy and commercial confidentiality of the owners. All investigations were conducted on blocks of Washington Navel orange plantings of 40-50 years of age.
The following investigations were conducted at each property and are outlined here. More details of the methods used are given under the relevant section later in the text. •
Farm Inputs and Outputs: growers completed questionnaires and two separate verbal interviews, in January 1998 and November 2001, on details of all farm inputs and outputs during the study period. Farmers were also asked informally about inputs and outputs throughout the duration of the study.
Soil Physics and Chemistry: soil samples were taken for chemical analysis on one occasion, in March 1999.
Soil Biology: soils were sampled quarterly for arthropods and biannually for nematodes between August 1998 and July 1999, using a soil coring technique in a stratified random sampling protocol that differentiated samples of 0-5 cm and 5-10 cm depth and the row edges (tree underskirt) and middles.
Natural Enemies of Kelly’s Citrus Thrips: sampling for predatory wasps was conducted on one occasion in 2000.
Manual of Best Practice: this was developed through grower sub-committees allocated to develop best practice methods and audit sheets for each of the various topics in the manual. Each section of the manual was then audited and tested by peer groups on different properties.
1.5 Project Organization and the Roles of the Participants The emphasis we have placed on the development of a learning partnership between scientists and citrus growers has required the establishment of a key group for management of the project: the Citrus Steering Committee. This consists of all growers, as well as staff of CSIRO and Australian Landscape Trust (Fig. 1.3). Meetings were held quarterly, which coincided with soil sampling occasions, with extra meetings as required. At these meetings, results of the monitoring program were discussed and future activities planned. Interactions with the funding agencies have been conducted by staff of Australian Landscape Trust, who have also provided logistic support such as secretarial and support services, facilities for meetings, accommodation for visiting CSIRO staff as well as contributing to overall project directions and objectives, including a major role in facilitating the development of the code of best practice by the growers. CSIRO staff have managed the monitoring part of the project, contributing the scientific information to underpin development of the code of best practice, learning how citrus productions operate, gathering and collating information on production methods and informing citrus growers of the basic soil ecological principles. Good communication with growers was a very important factor in the success of the project, and in addition to quarterly meetings and reports, growers were kept in touch with by telephone and e-mail. The growers provided the orchards, in which the research was conducted, their expertise in citrus production systems, as well as having ownership and control of the overall direction and activities of the project. During the first part of year 1, Dr Paul Dalby, then of the Waite Institute, University of Adelaide was contracted to conduct a number of biological chemical and physical tests on soils at the eight properties. These included a survey of earthworms, an estimation of the rates of ecotomycorrhizal fungal colonisation of roots of citrus trees, and measurements of soil
compaction, pH, salinity, water infiltration, water holding capacity, soil carbon and nitrogen. The data from these studies were written up and submitted in a report to Bookmark Biosphere Reserve (Dalby, 1999). Some of the tests, notably soil carbon and nitrogen, were later repeated by us, and are included in the present report. Otherwise, these data are not included in full in the present report, though some of the findings are mentioned in the text with due acknowledgement of their source.
Citrus Sustainability Group
Riverland Citrus Growers
Facilitators Australian Landscape Trust
Funding Agencies Natural Heritage Trust Government of South Australia Murray Darling Basin Commission River Murray Catchment Water Management Board
Fig. 1.3 Organization of the project “Monitoring in Pursuit of Ecologically Sustainable Development and Best Practice” (NHT Murray-Darling 2001 Program).
Chapter 2. ECOLOGICALLY SUSTAINABLE AGRICULTURE Sustainable agriculture: A whole-systems approach to food, feed, and fibre production that balances environmental soundness, social equity, and economic viability among all sectors of the public, including international and intergenerational peoples. Inherent in this definition is the idea that sustainability must be extended not only globally but also indefinitely in time, and to all living organisms including humans. Stephen R. Gliessman, 2000 An Ecological Definition of Sustainable Agriculture http://www.agroecology.org/principles/ecosustdef.htm 2.1 Biodiversity Drives Ecosystem Processes Natural and agricultural systems are dependent on the natural resources of soil, water and biological diversity. Each of these resources contributes to the productivity and integrity of agricultural ecosystems. Without their maintenance, agriculture is unsustainable. Maintaining natural resources requires some understanding of the processes that operate in agricultural ecosystems, and of the key groups of organisms that drive these processes in the soil, in water, and in above- ground vegetation. Example: The nitrogen cycle involves nitrification, nitrogen fixation (free-living and symbiotic), conversion of ammonia to nitrite to nitrate, decomposition of organic matter and mineralisation of organic nitrogen. Bacteria are involved in all of these processes. Fungi and soil animals are involved in some, predominantly to do with mineralisation. Could you run a nitrogen cycle with bacteria alone? Perhaps, but it would be nowhere near as efficient as it could be. It would run a lot better with fungi and soil animals to complete the recycling loop. 2.1.1 Ecosystem Functions Mediated by Soil Fauna • • • • •
Decomposition and nutrient cycling through the action of decomposer organisms; Regulation of microbial biomass and activity through the action of grazing orga nisms; Influence on microbial community structure through the effects of grazing and the dispersal of fungal spores and bacteria; Mediators of food web stability through the action of predators: natural enemies of pests; Influence on soil structure and microhabitats through the action of earthworms, termites and ants
2.1.2 Biodiversity and Stability • The higher the diversity of species, the higher the diversity of functional groups and the more stable the system; • High diversity of functional groups = more free biological goods and services; • Low diversity of functional groups = need to introduce substitutes: cost implication. The most common interaction between organisms is that they eat each other; • Thus systems with high species diversity have more complex food webs; • More complex food webs allow for greater flexibility in food resource switching; • More options in food resources means more species survive = more functional groups = more jobs get done. Table 2.1 Characteristics of Sustainable versus Synthetic Production Systems
• • • •
Sustainable Low/reduced agrochemical input; High biodiversity - complex ecosystem; Tends towards stability; Uses existing biological resources.
• • • •
Synthetic Relatively high agrochemical input; Low biodiversity - simple ecosystem; Tends towards instability; Marginalizes existing biological resources
2.2 Ecosystem Goods and Services Nutrient cycling, pollination, soil fertility, etc. are ecosystem services: jobs that are all done by various organisms, including bacteria, fungi, protozoa, insects and other invertebrates. To quote Constanza et al. (1997): “The services of ecological systems and the natural capital stocks that produce them are critical to the functioning of the Earth’s life-support system. They contribute to human welfare, both directly and indirectly, and therefore represent part of the total economic value of the planet.” Example: The soil and above ground vegetation provides the habitat for a complex and diverse community of invertebrate animals. The most common interactions these organisms are likely to have is that they eat each other. The resulting food web is a representation of the interactions between predators and prey: a map of who eats whom. The greater the biological diversity of the community, the more complex are the linkages in the food web, and, in general, the more resilient the system is against incursions of species which are likely to become pests. There is a relationship between the structural complexity of the higher plant communities of an agroecosystem (and any adjoining remnant natural vegetation) and the amount and quality of available habitat it provides to invertebrates. Thus, orchards are structurally more complex than wheat fields and insect diversity is many times higher. 2.3 Modern Conventional Agriculture Most modern conventional agriculture is unsustainable because it tends to concentrate on short-term productivity at the expense of long-term ecosystem health. The reason for this is because the practices of conventional agriculture have been developed primarily with economic goals in mind: maximising productivity and profitability, and do not take into account their effects on natural resources and ecosystem health. The reliance of modern agriculture on monocultures, tillage, irrigation, synthetic fertilizers, pesticides and fossil fuels results in intensive production of crops, but at significant environmental cost and degradation of ecosystem services. Even agricultural systems that may appear sustainable in their use of water, nutrients and other resources may in fact not be so because of unforseen interactions between different components of the biogeochemical system. An example of this is in stone-pome fruit orchards in the Goulburn Valley in northern Victoria. Most plantings are on duplex clay loams with less than 1.5% organic matter. The subsoil of red clay in and around Shepparton has a natural pH of about 8.2. In a survey of orchards in this area, it was found that 45% of orchards had soil pH below 5 (CaCl). The drop in pH has been estimated as 3 units in 50 years. At this rate the soil will be unfarmable in another 20 years. This has necessitated a program of liming and gypsum amelioration. This rate of acidification is barely noticeable year-by-year, so it would be unlikely that it was picked up in the short term by any monitoring program that was part of an environmental management system.
2.4 Structural Complexity Facilitates Biodiversity Structural complexity describes the ‘shape’ of an ecosystem, but also refers to the diversity of habitats that are available within it to be colonised by plants, microorganisms and animals. The more structural complexity in a system, the more organisms can live in it. In agroecosystems, there are two major types of structural complexity. In perennial cropping systems, such as orchards, the structural habitat complexity is almost entirely spatial, and provided by the trees - the microhabitats on leaves, stems, bark, fruit and flowers – as well as by the quality and diversity of the understorey vegetation or cover crop. By way of contrast, in annual cropping systems such as wheat, structural complexity of habitat is generated mostly by temporal variation provided by rotations with other crops such as canola, planting of break crops, pasture, or use of fallow periods. One of the most important strategies for managing biodiversity in agroecosystems is building habitat complexity into the system. Example: Desert sand is composed of particles of silica. At a microscopic scale, the habitats available within dry sand consist of the gaps between the sand grains. In order for organisms to live there, there has to be access to water. If one adds water, the system will support simple single-celled algae, capable of making sugar through pho tosynthesis, and that is about all. Add a small amount of organic matter, thus making the system structurally more complex (because of the variety of particles and different surfaces you have just introduced), and you provide habitats for a variety of bacteria, fungi and protozoa. You now have the beginnings of a system of nutrient cycling: living organisms recycle the remains of their predecessors. Add flowering plants, and you have a series of habitats on the plant itself, including flowers, leaves, stems and roots, that support insects, mites, nematodes and fungi, which provide food for other organisms. The plants themselves provide food for birds and mammals. The bulk organic matter supplied to this rudimentary soil by dead plant tissues - its different sizes and quality – adds still further complexity. This is how ecosystems develop: by colonisation, succession, and the addition of diversity. 2.5 Biodiversity as a Resource for Farmers All living organisms are a potential resource in agricultural ecosys tems, even harmful ones such as weeds. Example: Weeds have been referred to as ‘plants that are in the wrong place’. They can have a negative effect on a crop through competition and allelopathic effects (allelopathy is the release of chemicals from a plant that inhibits growth of other plants). Weeds can be used as a resource by allowing them to grow and then cutting them and using them as mulch. This has a whole host of important and far-reaching effects. It reduces the amount of soil water lost by evaporation; it increases the organic matter content of the soil, which provides food for micro-organisms and soil invertebrates, thus encouraging soil biodiversity; it improves the structure of soils, particularly if they are very sandy or very clayey. In sandy soils this has the effect of increasing irrigation efficiency by reducing the rate of irrigation water and nutrient leaching through the soil profile. This, in turn, retains nutrients in the soil, where they would otherwise run off and contribute to pollution of waterways through eutrophication. Also, cutting and mulching reduces the need for herbicides that could damage the soil biota. 2.6 Sustainable Agriculture –Defining Principles It is not a straightforward process to determine whether a particular agricultural system is sustainable, partly because that system will sit in a broader ecological unit of catchment or region, with which it interacts and partly because proof of sustainability (i.e. that the system
will function indefinitely), cannot be demonstrated in the present. The degree of sustainability of an agroecosystem has to be inferred from comparisons with systems that are unsustainable. The measure of ecological unsustainability is whether the farming methods result in continuous, cumulative environmental degradation and reduction and/or disruption of ecosystem function. Sustainable agricultural production has the following minimal set of characteristics. These characteristics apply to virtually any production system, be it irrigated horticulture, dairy farming or dryland wheat. 1. There is a minimal polluting effect on groundwater, surface water, atmosphere and soil, and that effect is not cumulative and does not compromise other parts of the system. In other words, the existing ecosystem processes (services) that deal with water filtration, detoxification and decontamination remain effective; 2. Soil fertility and soil ecosystem function are preserved and enhanced, if possible; soil erosion and loss of soil nutrients are reduced or eliminated; 3. Water is used efficiently, in a way that allows for the recharge of aquifers, and which does not compromise the needs of natural ecosystems or local communities; 4. Resources are used that come from within the agroecosystem itself wherever possible. External artificial agricultural inputs are substituted for ecosystem service-based products, such as natural nutrient cycling and mineralisation of plant residues through the action of a biodiverse soil biota and pest control by conservation biocontrol using natural enemies. Sustainable farmers cultivate and manage the biodiversity of their farms. It is biodiversity that does the work and delivers the goods that would otherwise have to be provided by artificial inputs. 5. A knowledge base, lodged within the local community, is developed and maintained, both for the implementation and maintenance of sustainable agriculture, but also as a means of developing equity for farmers in the control of market access, agricultural resources, supply chains and other major agricultural economic drivers; 6. The local community are integrated with the natural and agricultural landscape to produce a resilient and sustainable regional economy. The core principles on which sustainable agriculture is based and how it operates are understood by the key players in that regional economy; 7. The management of sustainable agriculture is governed by the application of ecological principles (especially the ecology of ecosystems). Ecosystem ecology deals with the transformation, flux and accumulation of energy and matter in soils plants and the environment. All ecosystems, be they natural or agricultural, are subject to the same ecological rules. Agronomy, the discipline that has governed the practical management of agriculture hitherto, is a mixture of other disciplines, including soil science, plant physiology, genetics and ecology. As such, and like economics, it lacks a theoretical, predictive, unifying basis derived from experimental observations. Ecology, on the other hand, has such a basis, and is therefore a more powerful tool to explain and predict accurately the consequences of change on the entire system. This does not mean that application of ecology is at the expense of agronomic knowledge and practice. Far from it.
Agronomy remains a practical mainstay, but ecology provides an extra, whole-of-system dimension; 8. Economic sustainability is incorporated as an integral part of ecological sustainability; 9. Total resource inputs are taken into account on a local, regional, national and global scale. Ecological accounting provides a whole-of-systems approach. Thus, the cost of artificial fertiliser is represented not just by the dollar purchase price, but includes the complete economic, social and environmental costs of manufacture; 10. In sustainable agricultural production systems the aim is to live off the interest of our natural capital and not the principal. 2.7 Environmental Management Systems A broad definition of an environmental management system is a means of managing the impacts of an enterprise on the environment. Typically, it operates in a cyclical fashion of continuous improvement, or adaptive management, as illustrated in Fig. 1.2, involving planning, implementing and monitoring changes, then reviewing and improving. At a farm scale, EMS may be adopted in order to fulfil sustainability aspirations of the farmer (and the consumers of the farmer’s produce), improve access to markets by achieving product differentiation, or improve financial and environmental outlooks for the enterprise. At regional and national scales, EMS is seen as a means of adopting and integrating sustainable agricultural practice in order to improve environmental, social and economic outcomes. The reasoning goes that improving natural resource management (NRM) through adoption of EMS will also allow for gains in market advantage for agricultural produce, as well as facilitating NRM planning and monitoring at catchment and regional scales. Adoption of EMS by Australian agriculture is currently the subject of much activity and debate. The two major trends, which should complement each other, are: i) that characterised by the present project, whereby a group of motivated farmers develops their own EMS scheme, tailored for their industry and regional characteristics; ii) the development of a coordinated national framework for EMS adoption across industries and regions (Environmental Management Systems Working Group, 2001). There are myriad ways of developing and accrediting EMS (cf. Carruthers and Tinning, 1999 for examples). National accreditation standards such as ISO 14001 represent one approach that is attractive to many farmers. Others have preferred to develop their own peeraccreditation schemes, whereby farmers seeking accreditation are assessed by other members of the group that have developed the EMS. The advantage of this approach is that because it relies on discussions, meetings, detailed farm audits, exchange of information and advice amongst farmers, it forms a powerful social learning and networking process for the farmers. The planning, implementing, monitoring, modifying and learning cycle of the EMS thus becomes a collective experience rather than a transaction between farmer and auditor. What matters most, regardless of the details of the EMS or its accreditation system, is that environmental improvements are clearly quantified. What to monitor becomes a vital question, and one that has underpinned much of the science contained herein. The process of what to monitor is made easier through taking a whole-of-systems approach. In the present study we have paid special attention to this approach, especially through input-output analysis. It has become relatively straightforward within such a framework to set meaningful monitoring objectives for water conservation, management of pests, weeds, nutrients and soils and other environmental objectives (cf. Appendix 8).
Chapter 3. FARM INPUTS AND OUTPUTS 3.1 Introduction The definition of sustainable agriculture at the beginning of Chapter 2 encompasses ecological (environmental), economic and social sustainability, in the sense of Goodland and Daly (1996). Social sustainability mainly falls outside the scope of this project. However, it is possible to investigate aspects of ecological and economic sustainability of citrus production systems in terms of energy efficiency, nutrients and dollar costs and returns. This approach to indicators of sustainability has been used recently as part of an investigation of apple production systems in Washington State, USA (Reganold et al., 2001). Inputs are defined as labour, fuel, fertiliser, pesticides, water and other materials and services required to produce the crop. Outputs represent the yield of fruit. Both inputs and outputs can be measured in terms of dollar value or units of energy. It is also important to consider the inputs and outputs of nutrients, because of the desirability to maximise nutrient use efficiency and cost-effectiveness on- farm and minimise detrimental effects of nutrient mobility and loss on adjacent terrestrial and aquatic ecosystems. Furthermore, an assessment of nutrient inputs and outputs is crucial to an interpretation of the soil chemistry data presented in Chapter 4. The analyses described in this chapter cover the year 1999/2000. 3.2 Inventory of Inputs in Citrus Production in the Riverland: Fertilisers and Nutrient Sprays, Pesticides and Herbicides, Water 3.2.1 Fertilisers Growers use a wide range of fertilisers and application rates (Table 3.1). The two organic growers and Conventional 1 used fertilisers of organic or natural mineral origin exclusively, whereas Conventional 1, High-tech 2 and Pesticide-free 1 used only synthetic mineral fertiliser. High-tech 1 and Pesticide- free 2 used a mixture of organic and synthetic fertilisers.
Alroc (crushed rock mineral fertiliser) Ammonium nitrate (Nitram) Blended fertiliser (N,P,K,Ca,S,Mg) Blood and bone Calcium nitrate Composted cow manure Composted duck manure Composted pig manure Muriate of potash (potassium chloride) NPK (10:4:4) Potassium nitrate ‘Rapid Raiser’ poultry compost Superphosphate (single strength) Urea
Table 3.1 Ground-applied fertilizers, applied as solids or in solution by fertigation, as used by growers (tonnes/hectare/year). Amounts stated are those provided by growers.
0.05 0.38 1.2
0.4 0.08 2
5 3 5 0.2
0.3 0.075 0.5 0.7
3.2.3 Foliar Nutrient Sprays Foliar sprays are used to correct plant micronutrient deficiencies as identified by foliar analysis. The nutrients are absorbed through the stomata of the leaves. Micronutrients, required in relatively small quantities, can be supplied effectively in this way, thus avoiding the problem whereby metals such as copper, iron, manganese and zinc, become attached to the surface of clay particles in the soil and so become unavailable to plants. Foliar nutrient sprays are also intended to provide a quick macronutrient (nitrogen, phosphorus, potassium, calcium, and magnesium) boost to the new leaves. The benefits of foliar fertilization with macronutrients are more controversial than with micronutrients. Leaves are inefficient at absorbing fertilisers, especially N, P, and K: primarily the job of the roots. Some researchers claim that foliar sprays of urea improve fruit set, development and increase yields. Others claim that foliar applications of N, P and K do not consistently increase yield and can lead to yield reductions. Macronutrients are mostly adequately supplied through root uptake from the soil. A considerable proportion of the foliar spray application drips off the tree into the soil in any case.
Ammonium nitrate Calcium nitrate Iron chelate/Lig-iron Magnesium sulphate Manganese sulphate Mantrac 500 (Manganese) Potassium nitrate Urea Urea phosphate Zinc sulphate Zintrac 700 (Zinc)
Table 3.2. Foliar nutrient sprays, as used by growers (kg active ingredient/ha/yr). Amounts stated are those provided by growers.
37 20 1.4 2
6 0.8 40 80
16 7 6
9 9 6
3.2.4 Pesticides and Herbicides Use of insecticides, fungicides and herbicides by growers is determined by the following major factors: 1) orchard management and production philosophy: organic and pesticide- free growers do not use insecticides at all and herbicide use is minimalised to spot-spraying by pesticide- free growers; 2) export requirements: fungicide use by organic and pesticide- free growers is confined to the use of copper oxychloride and copper hydroxide, predominantly for the control of Brown Rot (Phytopthora citrophthora.), Citrus Septoria Spot (Septoria spp.) and Anthracnose (Colletotrichum gloeosporioides). This is a quarantine requirement for growers exporting their fruit; 3) seasonal variation in pest populations and disease prevalence. Thus, pesticide inputs are likely to vary quantitatively and qualitatively between years.
Summer oil Trichlorfon/chlorofos 1 Herbicides 1 Bromacil 1 Diuron 2 Glyphosate 1 Simazine Fungicides 1 Copper oxychloride Copper hydroxide Mefenoxam1 4 (Ortho)phosphoric acid Molluscicides Snail bait 4
Pesticide Nematicides Aldicarb Insecticides Chlorpyriphos 1 2 Methidathion
Table 3.3. Pesticide inputs (kg of active ingredient/ha/yr1 or L/ha/yr 2 ). Amounts stated are those provided by growers, or calculated by us from published data on recommended application rates3 . X = used, but amount not specified.
1.7 0.6 3
108 3 1.2
Dylox Hyvar Karmex, Direx Roundup Herbex, Simadex
2 3 1.6 2
4 Kocide Ridomil Foli-R-Fos 400
0.4 1 5 1 4
1 9 X
has triple role as fungicide, fertiliser and pH corrector.
3.2.5 Water Irrigation water use, in megalitres per hectare per annum, is given in Table 3.11 for those properties where data was available. It has not been possible to obtain data on water use in every case. In some instances, water use figures approximate to those for the water allocation (although this does not mean that all the allocation was used). In other cases, usage is substantially lower than allocation. The regulations governing water allocations, use, trading and leasing are complex, politically-charged and the subject of much debate, controversy and acrimony. This scenario makes hard data on water use more difficult to collect than for any other input, including farm finances. It has only been possible herein to analyse water use in relation to dollar value of production. 3.3 Calculation of Nutrient Inputs and Outputs 3.3.1 Inputs From the data on fertiliser and foliar nutrient spray inputs, we calculated the percentage composition in each product of the following nutrients: carbon, nitrogen, phosphorous, sodium, potassium, calcium, magnesium, manganese, copper, iron and zinc. Percentage composition combined with known or recommended application rates for each product allows for calculation of the annual input per hectare (Table 3.4). The source information we have used for composition (and some application rates) is as follows. URLs were operational on September 1 st , 2002. 21
• • • • • • • •
Inorganic fertilisers: The Fertiliser Handbook Chapter 20, Technical Description of Fertilisers (Balance Agrinutrients, New Zealand) http://www.ballance.co.nz/thbook.html NPK (10:4:4): Percentage nutrient analysis data sheet, Hi Fert WMC Fertilisers Pty Ltd http://www.hifert.com.au/products/horti.html Zintrac 700 and Mantrac 500: Photosyn plc Product Information Page http://www.phosyn.com/webcom/home.html Urea phosphate: Oklahoma State University, Nitrogen Use Efficiency. http://www.dasnr.okstate.edu/nitrogen_use/N_Fertilizers/Urea_phosphate.htm Lig-iron: SJB Ag-Nutri Pty Ltd: http://sjbagnutri.com.au Alroc mineral fertiliser no. 3 mix: http://www.mineralfertiliser.com.au/analysis.htm Rapid Raiser: Neutrog – The Expert’s Choice – Rapid Raiser: http://www.neutrog.com.au/index/home Composted cow manure: Phyllis: a database containing information on the composition of biomass and waste ; University of Wisconsin Forage Research and Extension: Combs, S.M., Peters, J.B. and Zhang, L.S. Micronut rient status of manure ; North Carolina State University Soil Science Extension Program: SoilFacts: Dairy manure as a fertiliser source. http://ces.soil.ncsu.edu/soilscience/publications/ Composted duck and pig manure: grower’s commissioned reports SWEP Analytical Laboratories, Noble Park, VIC. Blood/meat and bone: average of nutrient content listed on bags of three proprietary brands of blood and bone.
All nutrient composition data was calculated on a wet weight basis, since it is in wet weight form that the inputs are applied. 3.3.2 Outputs Nutrient content of citrus fruit: USDA Nutrient Database for Standard Reference, Release 14 Nutrient Data Laboratory, Food and Nutrition Information Center, National Agricultural Library, United States Department of Agriculture: http://www.nal.usda.gov/fnic/foodcomp/Data/SR14/reports/sr14page.htm 3.4 Calculation of Dollar Value and Energy Value of Inputs and Outputs 3.4.1 Dollar Value Data on dollar value, or 1999 purchase costs, of inputs is derived predominantly from farm records, as is all data on crop yields and prices received by growers. For those products where data were not available, a list of current (March, 2002) prices was provided by Elders-RHT (Barmera Office), or from contacting manufacturers direct (Aventis – Temik application costs; Mineral Fertiliser Company – Alroc). These figures have been adjusted to 1999/2000 prices using Australian Bureau of Agricultural and Research Economics (ABARE) indices of prices paid by farmers, and terms of trade. A complete inventory of inputs and their estimated 1999 costs is given in Appendix 4.
3.4.2 Energy Value The data on energy inputs is based on their production energy costs (also called industrial cultural energy costs), i.e. the amount of energy required for their manufacture. We have not attempted to factor in intrinsic energy potential or availability of each input. Data on production energy costs of inputs comes from Pimentel (1980) as follows: • • • • •
Fuel: Cervinka in Pimentel (1980), p. 15, Table 1. Machinery: calculated as an average percentage (3.67%) energy value of total input production energy, based on Reitz in Pimentel (1980), p. 286, Table 1. N, P and K fertilisers (including transportation, storage and distribution): Lockeretz in Pimentel (1980), p. 23, Tables 1 and 2. Insecticides, herbicides and fungicides: Pimentel in Pimentel (1980) p. 46, Tables 1 and 2. Data on energy content of citrus fruit: USDA Nutrient Database for Standard Reference, Release 14 Nutrient Data Laboratory, Food and Nutrition Information Center, National Agricultural Library, United States Department of Agriculture: http://www.nal.usda.gov/fnic/foodcomp/Data/SR14/reports/sr14page.htm
3.5 Results and Discussion 3.5.1 Nutrient Inputs and Outputs The amounts of each nutrient derived from foliar sprays and fertilisers are provided in Appendix 1. Nutrient inputs and outputs per hectare are presented in Table 3.4. Averaged across the 8 properties, there is a surplus of all but one of the nutrients measured. The exception is carbon, which deserves particular mention. Carbon is not a plant nutrient per se. Plants fix their own carbon from atmospheric carbon dioxide during photosynthesis. Hence, we have simply recorded inputs and outputs in Table 3.4, rather than calculating the difference. Despite carbon not being a plant nutrient in the conventional sense, it is a vital requirement to make organic molecules of which soil bacteria, fungi and invertebrates are composed, and it is these organisms that drive ecosystem processes upon which the trees may depend for their health. There is a clear relationship between carbon inputs, soil organic carbon levels and abundance of soil invertebrates (cf. 4.3.2; Fig. 5.13). Nutrients with inputs most frequently lower than outputs were potassium (Conventional 1 and 2, Pesticide- free 1), calcium and magnesium (Conventional 1 and High- tech 2), though average inputs of calcium and magnesium were greater than outputs by 6- fold and 4- fold respectively. High-tech 2 had 6 nutrient inputs lower than outputs (N, P, Na, Ca, Mg and Fe); Conventional 1 had 4 (Na, K, Ca and Mg) and Pesticide- free 1 had 3 (Na, K and Fe). Nutrients with average input greater than output were manganese, copper and zinc (530-, 155-, 147-fold greater). Inputs were in excess on every property. Average inputs of iron, sodium and phosphorous were 68-, 30- and 9- fold greater than crop outputs. Fold-difference between inputs and outputs for manganese, copper and zinc was examined according to whether fertiliser inputs on each property included material of organic origin (i.e. Conventional 2, High-tech 1, Organic 1 and 2) or not (Table 3.5). There were markedly greater average excess inputs of manganese, zinc and copper on those properties that used composted animal manures, although only manganese excess was statistically significant. Manganese, copper and zinc are used widely in feed supplements for pigs, dairy and beef cattle and poultry. Copper and zinc also exert pharmacological effects at doses considerably higher than the normal dietary requirement of the animals. Excess metal trace elements used
as medicines, growth promoters or food supplements are excreted in the dung and tend to remain in its solid fraction following composting. In soils that receive long-term, high inputs of composted animal manures the potential exists for the accumulation of manganese, copper and zinc to levels that may pose a toxicit y threat to citrus trees. This threat could increase if the soils are becoming acidified through high inputs of organic matter. However, the actual risk is dependent on levels of plant-available forms, not total levels, and is probably low (cf. Section 4.4). These findings serve to emphasise the fact that the diversity of nutrients in composted manures means that farmers have far less flexibility in controlling inputs of certain nutrients than they have with inorganic fertilisers. Macronutrient levels may be adequate for crop nutrition, while at the same time micronutrients are present in excess. This further highlights the need for careful nutrient budgeting and the regular monitoring of nutrient concentrations of organic inputs. Calculating nutrient input s in fertilisers and outputs in the crop does not account for all sources and sinks of in an agroecosystem. In order to provide a ‘closed- loop’ accounting system, one would also have to calculate nutrient losses to watercourses and groundwater, loss to the atmosphere in the form of gaseous nitrogen and sulphur compounds (ammonia, nitrogen oxide, nitrogen dioxide, nitrous oxide), immobilisation of nutrients on clay minerals, as well as the rates of nutrient assimilation by citrus trees and the amounts of nutrients that are returned to the soil via decomposition and mineralisation of plant residues (Fig. 3.1). So can simple input-output analysis provide any practical information without a considerable amount of additional monitoring? Firstly, those elements with cycles that involve multiple biogeochemical transformations (carbon, nitrogen, phosphorous and sulphur) are more difficult to account for than micronutrient elements subject to more limited series of biogeochemical processes. For example, nitrogen input s to the orchard are derived from fertilisers and composts, atmospheric deposition, free- living and symbiotic nitrogen fixation, decomposition and mineralisation of plant residues, soil biota and their excretory products. By way of contrast, manganese inputs are derived from fertilisers/nutrient sprays, a small amount of decomposition and recycling and, under certain circumstances, some minor contribution from weathering of minerals in the regolith. Secondly, if the output of a particular nutrient in the crop is greater than the input, and the input is derived predominantly from fertilisers, then it is a reasonable prediction that there will eventually be a deficit of that nutrient unless the application rate is increased. Thirdly, if inputs of nutrients are in excess of crop outputs, and those inputs remain predominantly in the orchard soil and are plant-available, then not only is this a waste of money, but there is a risk of elevating nutrients to levels that could be detrimental. In the case of several micronutrients such as copper, manganese and zinc, there could be a long-term risk for development of toxicity symptoms. In the case of nitrogen excess, there is a strong likelihood that elevated foliar nitrogen will encourage an increase in leaf-damage by insect pests. Input-output analysis can provide a basic framework for nutrient budgeting that can then be refined and improved over time as part of the adaptive management process. Regular soil nutrient monitoring is encouraged as part of the Code of Best Practice (Appendix 8). Together with regular foliar nutrient analysis, this will provide valuable data on longer-term trends in soil nutrient status.
Nitrogen (kg) Phosphorus (kg) Sodium (kg) Potassium (kg) Calcium (kg)
63 5.25 57.75 11.02 1.50 9.52
0 0.35 -0.35 2.185 0.10 2.09 13.11 44.39 64.75 -20.3613.55 18.50 -4.95
4.2 14.93 -10.7348.45 5.00 43.45 269.7
4.5 93.00 0.58
0.49 -0.49 28.45
65.1 127.2 83.1
0.35 28.10 28.05
71.8 78.9 290.1
62.0228.0 151.75 62.61 89.1
5.13 77.97 26.4
5.67 20.73 43.5
4.90 38.6 51.538 4.94 46.6
0.38 -0.38 11.14
0.33 10.8 10.367 0.33 10.0
4.9 30.698 60.97 15.4
17.5 -17.50 213.8 17.50 196.30 204.1 17.10187.00 64.2 18.90 45.30 96.5 16.32 80.2 112.62 15.28 97.3
0.97 3.96 -2.99 17.64 1.13 16.51 18.84
0.22 0.01 0.21 2.14 0.003 2.137 11.88 0.0078 11.87 1.28 0.0127 1.27
9.89 3.84 0.0098 3.83 5.39 0.0085
5.4 5.3358 0.01 5.3
2.28 0.02 2.26
2.1 3.085 0.02 3.1
0.15 0.12 0.03 16.9 0.03 16.87
0.56 0.03 0.53 1.33 0.01 1.32 11.54
3.5 0.01 3.49 10.10 5.30
3.4 15.45 2.15
96 90.65 5.35 132.35 64.75 67.60 131.95 63.27 68.68 64.1 69.93 -5.83 65.3 60.38 0
93.1 -66.9 131.6
57.0 149.2 26.25
1500 2100 3.9 206.20
High-tech 1 Outputs
259.14 66.5 192.6 22.9 19.0
Table 3.4 Summary data on nutrient inputs and outputs per hectare per year, 1999.
3.9 25.74 14.1
3.7 17.6 16.825 3.72 13.1
0.02 1.38 2.10
0.17 -0.17 11.90
0.12 11.78 11.50
0.12 11.38 0.00
0.13 -0.13 15.05
0.11 14.9 7.6
0.03 3.49 4.18
0.02 11.52 1.32
4.3 9.83 21.3
0.02 10.08 1.80 5.20 0.00
Table 3.5 Fold-excess of inputs over outputs of metal micronutrients per property, according to whether fertiliser inputs include those of organic origin (O) or inorganic origin (I). Iron is not included because two properties had no discernable iron inputs. I 22 101 391 634 287 281
Manganese O 713 1523 884 1112 1058 350
Copper I 114 60 70 105 87 26
Zinc O 350 505 115 60 258 207
I 19 33 117 139 77 60
O 133 577 185 243 285 200
Foliar nutrient sprays
Loss to atmosphere Leaves stem and fruit
Atmospheric carbon, nitrogen and sulphur
Nitrogen fixation and deposition; sulphur absorption
Immobilisation on clay minerals and organic particles
Fig. 3.1 Nutrient sources and sinks in citrus orchards. Blue boxes represent outputs; green boxes represent inputs and brown boxes represent recycling processes. 3.5.2 Energy Inputs and Outputs The reason for investigating energy input-outputs ratios is because they represent an estimate of energy efficiency, and thus can be used as an indicator of sustainability (Reganold et al., 2001). Data on energy inputs and outputs is summarised in Tables 3.6 and 3.7 (cf. also Appendices 2 and 3). In Table 3.6, labour inputs were left as hours per hectare per year because of the lack of a uniform methodology for converting them into energy equivalents. Energy inputs for composted animal manures have not been included because the manure is a
waste product from other industries (dairy, poultry and pork) and therefore has little or no production energy cost. Only energy costs of transporting the manure to orchards have been included in Table 3.6. Organic growers were most energy-efficient (6-7 times more energy produced than consumed), then Pesticide-free (1.5-1.7 times), then High-tech (0.7-1.8 times), then Conventional (0.2-1-2). The main energy efficiencies achieved by organic growers were in use of composted animal manure because its production energy costs were not debited (cf. above), and because they do not use pesticides. The largest proportion of energy inputs are derived from synthetic fertilisers. Each tonne of nitrogen fertiliser has an oil-equivalent energy requirement of ca. 1.8 tonnes (Leach, 1976). Next comes pesticides, then electricity (Table 3.7). Two growers, Conventional 1 and High-tech 1, consumed more energy than they produced, mainly because of high inputs of synthetic fertilisers and pesticides. In contrast with their energy-efficiency, organic growers were least labour-efficient especially regarding hours spent harvesting (Table 3.8). On average, 7.5 hours of labour input were required for the production of a tonne of organic oranges; 7.4 hrs for High- tech; 4.6 for Conventional and 3.6 for Pesticide- free.
Size of orchard (ha) Total Labour (hr ha yr) Inputs - production energy (GJ ha yr) Electricity Fuel & transport Machinery Total fuel, machinery & transport Fertiliser Inorganic nitrogen Inorganic potassium Inorganic phosphorus Foliar nutrient sprays (non N, P & K) Total fertiliser Insecticides Herbicides Fungicides Total pesticides Total energy inputs Outputs Fruit yield (t ha yr) Energy outputs in fruit yield (MJ ha yr) Input/Output ratios Energy: GJ output/GJ input Energy: GJ output ha/labour hour Labour (hr) required to produce 1 tonne of fruit
Table 3.6 Energy Value of Inputs and Outputs for 1999 in Gigajoules per Hectare per Year
6.48 17.53 7.9 31.91
6.6 3.2 0.17 9.97
8.88 8.26 1.98 19.12
11.64 8.98 0.86 21.48
7.2 2.23 0.02 9.45
6.9 1.26 0.01 8.17
9.27 7.5 8.06 5.59 4.33 6.42 1.0 0.75 1.59 15.86 12.58 16.07
190.53 0.84 6.74 0.2 198.31 14.31 1.79 0.86 16.96 247.18
0 3.35 0.09 0.32 3.76 0 0 0.86 0.86 14.59
2.28 0 4.9 0.91 8.09 39.76 2.09 3.89 45.74 72.95
3.83 1.34 0 1.12 6.29 15.14 1.47 0.65 17.26 45.03
0 0 0 0 0 0 0 0.43 0.43 9.88
0 0 0 0.28 0.28 0 0 0 0 8.45
25.61 16.89 22.44 0 0 0.69 0 0 1.47 0.98 1.15 0.62 26.59 18.05 25.22 0 0 8.65 0 1.36 0.84 0.54 0.97 1.03 0.54 2.33 10.52 42.99 32.95 51.81
37.8 32.6 33 63.88 55.09 55.69
0.24 0.31 5.4
1.16 0.45 3.8
0.7 0.23 7.5
1.84 0.24 7.1
5.99 0.16 10.3
6.84 0.36 4.6
1.49 0.35 4.9
1.67 0.73 2.3
1.08 0.28 6.0
3.5.3 Dollar Inputs and Outputs Data on dollar inputs and outputs is summarised in Tables 3.8 and 3.9 (cf. also Appendix 4). Input costs per hectare per year ranged from $1213 (Conventional 2) to $8982 (High- tech 1), with an average of $5786. Organic, High-tech and Conventional production costs tended to be higher than average and Pesticide- free costs lower. But costs per hectare do not take yield into account. When expressed in terms of yield, the cost of producing a tonne of oranges varied
between $72 (Pesticide- free 2) and $209 (Organic 1), with an average of $148 (cf. Table 3.8). There is a tendency for high input costs to be accompanied by high yields and low input costs by lower yields (Fig. 3.2). However, when the two outliers (Conventional 2: $1213 per ha, 10 t ha;
12.2 11.3 2.7 11.1 62.7 100
25.9 72.9 81.7 21.6 22.8 19.9 22.6 14.9 13.0 13.1 1.9 0.1 0.1 2.3 2.3 14.0 0.0 3.3 61.9 54.8 38.3 4.4 0.0 1.2 7.0 100 100 100 100 100
15.5 12.4 3.1 48.7 20.3 100
45.3 21.9 1.2 25.7 5.9 100
7.1 3.2 2.6 80.2 6.9 100
Electricity Fuel & transport Machinery Fertilisers Pesticides Total
Table 3.7 Itemised Input Energy (Excluding Labour) as a Percentage of Total Input Energy
High-tech 2: $8982 ha, 49 t ha) are removed, there is no association between input costs and yield. Over a relatively broad input cost range ($2330-6680 ha), there is a relatively narrow yield range (30-37.8 t ha). Table 3.9 shows the percentage breakdown of input costs. Labour accounts for the highest percentage (average 52%), then fertilisers and nutrient sprays (11%), then insurance, super and admin. (7.4%) then machinery (7.2%). Labour costs tended to be higher for High-tech producers and organic producers, but for different reasons. High-tech production tends to be more labour- intensive, while organic production tends to have lower input costs from other sources, making labour a larger component. Figures on costs of production presented herein are broadly in line with those in the recent Productivity Commission inquiry report into citrus growing and processing (Productivity Commission, 2002). Their Tables C1 and C2 show draft cash flow budgets (dollar inputoutput analyses) for Washington navel oranges produced in the Murray Irrigation Area and in the Sunraysia Regions over a 20 year period from initial planting. The figures for years 10-20 are most comparable with those in the present study, and show that in both regions total cost per hectare per annum was similar (MIA: $7,027; Sunraysia: $7,175); around 19% higher than for Riverland growers. Estimates of total income for MIA and Sunraysia were only 58% of those realised by Riverland growers, based on an income estimate of 35 tonnes per hectare at only $350 per tonne.
50 105 N/A 31.5
30 N/A 4
2.5 189 5.4
4 38 3.8
34 130 622
388 535 66
232 79 296 200 47 320 29 133 13 4706 157
35 10 30 600 640 585 21000 6400 17550
561 275 270 322
2 50 70 100
216 1809 130 106 117 39
N/A 220 265 0 0 0 12
10 40 2 20 4 76 2.3
30 92 70 11 48 6 198 5.7
12 362 10.3
N/A 132 7 1.3 7 11 159 4.6
107 60 2 12 3 184 4.9
Size of orchard (ha) Harvesting wage rate ($ hr) Labour (hr ha yr) Labour – thinning Labour – picking Labour - grading/packing Labour – pruning Labour - irrigation/general maintenance Labour - weed control Total Labour (hr ha yr) Hours of labour per tonne of fruit harvested Inputs - dollar value ($ ha yr) Harvesting labour Contract operations Hedging Crop monitoring Grading/packing Water – irrigation Fuel + farm cartage General maintenance, equipment Machinery - interest, depreciation Insurance, registration, superannuation Administrative and office expenses Electricity Fertiliser Foliar nutrient sprays Insecticides Herbicides Fungicides Miscellaneous* Total inputs ($ ha) Input costs ($) per tonne of citrus Outputs Fruit yield (t ha yr) Average price per tonne ($) Fruit revenue ($ ha yr) Input/Output ratios $ output/$ input
Table 3.8 Dollar Value of Inputs and Outputs, 1999
62 47 100 285 247 256 181 546 132 269 512 45 70 36 30 179 5786 148
43 88 170 N/A 148 184 309 209 43 0 0 12
400 200 100 N/A
388 94 55 135 50 18 224 8982 183
100 600 530 400 N/A 110 N/A 230 509 5 0 0 0 300 5163 151
49 737 36113
35 34.2 625 606 21875 20725
37.8 640 24192
32.6 33 679 639 22135 21249
255 170 350 120 N/A 240 728 0 0 0 10
250 278 78 0 96 17
*Wetting agent, hormones, goose husbandry costs.
From the standpoint of economic sustainability, considerable scope for reduction of input costs lies in improving labour productivity. For example, there is almost five- fold variation in total labour hours per tonne of fruit harvested (2.3-10.3 hours per tonne; Table 3.8). On average, harvesting time accounts for 47% of labour hours, or 25% of total input costs.
48.6 59.3 74.4 0.64 4.3 3.5 2.459 5.9 2.3 11.8 0.7 6.4 5.9 18.8 ND 5.6 4.3 3.3 15.9 1.7 10.0 9.1 4.9 0.1 100 100 100
39.5 0.2 4.0 13.6 ND 17.6 24.3 1.0 100
52.0 10.3 5.0 10.9 ND 4.0 8.8 9.1 100
Harvesting labour & contract operations Irrigation water Fuel & transport Machinery: maintenance, interest, depreciation Insurance, administration, superannuation Electricity Fertilisers, nutrient sprays Weed control, pesticides + additives Total input costs
Table 3.9 Itemised input dollar costs as a percentage of total input dollar costs
48.0 72.1 36.3 51.7 11.6 1.2 15.9 5.8 10.3 2.4 8.0 4.9 7.7 4.6 4.0 7.2 2.1 4.0 ND 7.4 4.5 8.4 10.0 6.9 10.0 6.9 12.0 10.8 5.8 0.3 13.8 5.3 100 100 100 100
ND = no data provided.
Fruit yield ($ ha yr)
50 40 30 20 10 0 0
Input costs ($ ha yr)
Fig. 3.2. The association between input costs per hectare and fruit yield per hectare. The pattern is identical if revenue ($ ha yr) is substituted for fruit yield. Orchard layout, tree height and degree of pruning and thus ease of access to fruit for pickers, are just some examples of factors that are likely to increase harvest labour productivity. Such factors vary considerably from orchard to orchard (cf. Fig. 6.4). Dollar output- input ratios (one measure of before-tax profitability) varied from 3:1 (Organic 1) to 9.5:1 (Pesticide- free 2) with an average of 3.67:1 (calculated from average fruit yield in $ ha yr divided by average total input costs in $ ha yr; not from averaging $input/$output ratios, which gives a figure of 4.88:1). In other words, for every $1 spent on production, average income from sale of fruit is $3.67. Dollar input-output ratios were markedly higher for pesticide- free growers than the other three groups because they had lowest input costs, and achieved relatively high yields and prices per tonne (Table 3.10). Organic producers had relatively high yields, but high input costs and low prices. These comparisons are indicative only, being based on a sample size of n=2 for each management category. High-tech 2 achieved highest yields and prices but these were not enough to offset 30
the very high input cost, and contrasts with High-tech 1 with moderate inp ut costs but low yields and prices. Conventional 2, ranked third highest $ input/output ratio, had lowest input costs, reasonably high prices, but had the lowest yield, three times lower than the next lowest. Conventional 1 had high input costs, good yield but achieved relatively low price. When ranked by $ profit per hectare (i.e. fruit revenue in $ per hectare minus input costs per hectare, rounded to nearest $100), the Pesticide-free orchards 1 and 2 achieved $20,000 and $19,800 respectively, compared with $12,800 and $27,100 for High- tech 1 and 2, $14,600 and $15,600 for Organic 1 and 2 and $14,300 and $5,200 for Conventional 1 and 2.
Input costs Yield Price $ Input/Output ratio $ profit per hectare
Table 3.10. Ranking of orchard management categories by input costs, yield, price per tonne achieved for fruit, $ Input/Output ratio and $ Profit per hectare (input costs: 1 = lowest; yield, price, $ Input/Output ratio and $ Profit per hectare: 1 = highest)
6 3 7 7 6
1 8 3 3 8
4 7 8 6 7
8 1 1 4 1
7 3 5 8 5
5 5 6 5 4
3 2 3 2 2
2 6 2 1 3
3.5.4 Water Average water use was 9.8 ML ha yr (Table 3.11). This compares with an average of 8.03 ML ha yr for the seven agricultural production categories given in the ABS Water Account for Australia 2000 (Table 3.12; Australian Bureau of Statistics, 2000b), and was second highest per hectare after rice. The value of production per megalitre was highest at $2,171, compared with an average of $810. In 1998/1999 the cost of water was ca. $65 per megalitre. The revenue, or crop value, per megalitre of water used varied from $1,463 ha yr at High-tech 1 to $4,025 at Pesticide- free 1. There is too little data available to draw conclusions concerning the relationship between management type and water use or average of crop value per megalitre. The capacity for improvement in water use efficiency is quite high, since most properties were not using micro- or drip- irrigation systems, but conventional mid-row or under treeskirt. Having said that, none were using overhead systems either. There is no channel irrigation of citrus in the area.
Table 3.11. Water use in relation to value of production. ND = no data available.
Water use (ML ha yr) ND ND 12 ND 12 8.75 6.01 10.2 9.79 Water use (ML tonne of fruit) 0.4 0.34 0.26 0.16 0.31 0.29 Value of production ($ ha yr) 2100 6400 17550 36113 21875 20725 24192 22135 21249 Average revenue per ML ($ ha yr) 1463 1823 2369 4025 2170 2171
Table 3.12. Comparison of water use in relation to value of production for different agricultural commodities and production systems (modified after ABS Water Account for Australia 2000). Commodity/Production System Riverland citrus (this study) Livestock, pasture, grains Vegetables Sugar Fruit (general) Grapes Cotton Rice
Water use (ML ha yr) 9.79 7.49 7.15 7.14 8.55 9.24 5.85 10.78
Value of production ($ ha yr) 21,249 2,162 12,604 2,985 12,476 8,726 3,581 2,035
Average revenue per ML ($ ML) 2,171 288 1,763 418 1,459 944 612 189
Water use and water use efficiency represent key factors in defining sustainable agricultural production. The critical role of water sets the scene for the rest of the production system and its economic and environmental “success’. The topic of irrigation water use in citrus production in the Riverland merits a far more detailed treatment than can be provided here, and is the subject of some stringent requirements under the Manual of Best Practice (Appendix 8). The record-keeping component of these will provide some valuable data on year-on-year improvements in water use efficiency. In summary, the results, and their implications, were as follows: •
Nutrients - on average, inputs of all soil nutrient elements are greater than outputs, with manganese, copper and zinc higher than the rest. In the medium to long term, there is a possibility that me tal elements could accumulate to levels that could be toxic to citrus trees, especially at those orchards that use fertilisers containing composted animal manures. These data emphasise the need for increased attention on nutrient budgeting and better monitoring tools and models to allow farmers to do so. Energy - Organic growers were most energy-efficient, then Pesticide- free, High-tech, and finally, Conventional. However, Pesticide-free growers were the most labour-efficient at harvesting, then Conventional, then High-tech, and finally Organic. Achie ving increased energy efficiency is far less likely in the short-term to bring economic benefits to farmers than will improving labour efficiency. This is because many of the biggest energy input costs relate to off- farm production and manufacturing costs, not to on- farm energy use. Nevertheless, energy efficiency for enterprises becomes important in its role as an indicator of sustainability; part of an EMS and Best Practice certification program. Adoption and compliance with such schemes could have significant economic advantages at the enterprise scale in the medium- to long-term. Dollars - The cost of producing a tonne of navel oranges varied between $72 and $209, with an average of $148. Organic production costs were highest, then High-tech, Conventional and Pesticide- free. Dollar output- input ratios varied from 3:1 to 9.5: 1 (average 3.7:1). High input costs were offset by high yields and very high fruit revenues by High-tech 2, whereas the two Pesticide-free growers kept costs down, and achieved good prices for their fruit and good profits. The relatively high costs of the Organic producers were not offset by achieving any premium price for their fruit, and their profitability was only middling. Low profitability of Conventional 1 was due to high input costs and low prices, of Conventional 2 because of very low yields due to disease, and of High-tech 1 because of low yield and price. At every property, there was scope for achieving greater financial sustainability through reducing input costs. One of the obvious ways of doing this is by making increased use of free ecosystem services.
Water - On average it took 290 kilolitres to produce a tonne of citrus, ranging from 160 kL at Pesticide- free 1 to 400 kL at High-tech 1. Despite this wide variation, citrus production, on average, achieved better dollar value per megalitre of water used than any other production system with which it was compared.
3.5.5 Concluding Remarks The input-output analyses presented here for profitability, nutrients, energy and water provide a basic framework to allow for the assessment of key indicators of sustainability. As presented, based on sets of figures for 1999, they can only represent a partial, comparative snapshot of the economic and environmental state of each enterprise. A consideration of yearon-year variation of inputs, input costs and outputs is beyond the scope of the present project. Nevertheless, the fact that primary data already existed in the form of farm records indicates that on-going monitoring of these key indicators could be incorporated relatively easily into the Manual of Best Practice for citrus production. Another limitation, in the assessment of profitability, has been the difficulty in obtaining uniform comparative data on fruit quality. The value of citrus production is not just about tonnage, but about quality. We have had to rely on yield in our assessments because it is an easy statistic to collect from growers. Probably one of the more useful outcomes of the present analyses is to demonstrate there is considerable flexibility within citrus production systems towards achieving ecological and economic sustainability. Enterprises will have specific priorities and varying degrees of flexibility, dependent on the constraints of existing production methods and ethos, business plans and financial status and willingness to adopt new practices. There can be no ‘one size fits all’ strategy for adoption of sustainable production, only a pick- list of guidelines and options. The selection of a particular approach will contain a careful, considered balance between benefits to the enterprise and to the broader environment. Achieving improvements to one at the expense of the other is not sustainability. In relation to indicators of sustainability, it is important to consider how citrus production shapes up in terms of its environmental, social and economic ‘footprint’ on the landscape compared with other production systems. In essence, it is a thirsty system, but it produces very high value crops, and water use could be improved considerably given sufficient investment and technology transfer. It supports relatively high levels of soil biodiversity compared with many production systems, and this is partly as a result of its perennial nature and the complexity of habitats that citrus orchards afford. Finally, citrus production supports a relatively high requirement for labour, especially seasonal/casual labour. The social and economic benefits that it affords to the local communities through the provision of jobs and income is more valuable as a rural “vitaliser” than, say, grain or livestock production.
Chapter 4. SOIL PHYSICAL AND CHEMICAL PROPERTIES 4.1 Introduction - the Soils of the Riverland Region The Riverland is contained within the Murray-Darling Plains soil and landscape region (cf. Butler et al. in CSIRO Division of Soils, 1983). The soils are calacarous sandy soils calcarosols according to the Australian Soil Classification (Isbell, 1996; Isbell et al., 1997). They associated with parallel dunes and ridges. Typically the sequence consists of earthy sands on the dune crests, solonised brown soils on their flanks, with sandy clays and loams and red-brown earths on the adjacent flats. The calcareous nature of the soils is evident especially at roadsides, where limestone nodules of limestone are abundant and widespread. The soils of the horticultural areas tend to be uniform, free-draining red-brown sands and sandy loams, and their calcareous nature may be modified by inputs of organic matter. Blackburn and Wright (1972) in their soil survey of the Loxton Irrigation Area (which covers the area from ca. 2 km SW of Loxton town to ca. 2 km N of Loxton North) give details of soil mapping schemes from the 1920s to 1960s covering other parts of the Riverland (eg. Lyrup, Renmark, Chaffey, Berri, Cobdogla, Kingston, Moorook, Waikerie) as well as the characteristics of the 18 soil types they identified (8 sands, a loam and 11 sandy loams) covering about 6,000 ha. The high-resolution map they produced is on a scale of about 1: 8,000 (i.e.. 100 m = 1.25 cm) and provides section numbers, allowing a good basic impression of the distribution of soil types on each property. Further, the authors give some useful considerations on soil types and land use, focussing on the implications for horticultural productivity, the suitability of soils for different fruit trees, irrigation systems, salinity and drainage. Although a proportion of this information is primarily of historical interest, much remains valuable baseline data, highly relevant to the present project. 4.2 Methods 4.2.1 Compaction, Water Infiltration, Water Holding Capacity, pH and Salinity These measurements were made at each property between August 1998 and February 1999. Brief details of methods are given by Dalby (1999). 4.2.2 Soil Chemistry Soil samples were taken for chemical analysis in March 1999. Soil cores used for extraction of arthropods were bulked by row position (edge or mid-row) and depth (0-5, 5-10 cm) for each of the three rows sampled on each block of Washington Navels. Thus, 12 samples were taken on each property. Samples were transferred to the soil laboratory at the Department of Forestry, Australian National University, Canberra, mixed, sieved, sub-sampled and analysed for total organic carbon, nitrogen, phosphorous, and total and plant-available cations, sodium, potassium, calcium, magnesium manganese, copper, iron and zinc, using flame spectroscopy. Details of preparation methods are given in Appendix 6. 4.3 Results 4.3.1 Compaction, Water Infiltration, Water Holding Capacity, pH and Salinity Data on soil compaction, water infiltration, water holding capacity, pH and salinity for each property are detailed in the report by Dalby (1999). A brief synopsis is provided here for the
sake of completeness. Compaction profiles for all properties were very similar and there was no significant difference between them. They varied from 12-19 kg cm-2 at 0-10 cm depth, peaking at 32-36 kg cm-2 at a depth of about 50 cm and then declining to 12-17 kg cm-2 .at 8090 cm depth. The average water infiltration rate of the 8 orchards was 1.5 cm per min (range: 1.1-2.36; standard deviation ± 0.5) and the average water holding capacity was 158.1 g per kg (range 143-228, standard deviation ± 28.0). There was no clear relationship between the two variables, with soils with low infiltration rates having high holding capacity and vice versa. Soil pH was around neutral to slightly alkaline for all orchards (deionised water: mean: 7.4; range: 7.15-7.57; calcium chloride: mean: 6.36; range: 6.2-6.71). Salinity (EC e) ranged from 0.9 to 1.8 dS/m, with a mean of 1.42, and was slightly higher under the trees compared to the mid-rows. Four properties had an EC e of greater than 1.6. First signs of salting may be visible at 2-4 dS/m EC e (Fogarty et al., 1993). 4.3.2 Organic Carbon Organic carbon levels varied from 1.7-51.6 grams of carbon per kilogram of soil, with an average of 10.7 g/kg (SD 14.3). There was significantly more organic carbon in soil cores from 0-5 cm than 5-10 cm depth (Fig. 4.1), but not between the edges and middle of the rows at either depth sampled (data not shown). There was no clear pattern that could be related to the management category of each property (Table 4.1), but the levels closely reflected specific soil management practices (cf. below). The lowest soil carbon content was at the Pesticidefree 1 orchard, the highest at the Organic 1 orchard which can be attributed to the considerable effort and investment spent on increasing soil carbon content since organic production commenced on the property in 1988.
Organic carbon (g C/kg soil)
40 Average 0-5 cm
Average 5-10 cm
Average 1-10 cm
25 20 15 10 5
Pe stic 2 ide -fre e Pe 1 stic ide -fre e2
Or ga nic
Or ga nic
Co nv en tio na Co l1 nv en tio na l2 Hi Hi gh gh -te -te ch c h2 Hi 1 gh ,A -te ldi ca ch rb 2, no Al dic ar b
Fig. 4.1 Average (arithmetic mean) soil organic carbon content at depths of 0-5 cm, 5-10 cm and 0-10 cm, March, 1999. On the basis of their soil management, the orchards can be divided into High Input organic carbon and Low Input organic carbon categories:
High input : use of at least two of the following: inputs of composted animal manures, plant residues and/or coal fines (cf. 3.1); regular slashing and mulching of the ground cover vegetation; active incorporation of prunings, mulched or unmulched; manures, ground cover mulches, prunings, coal fines. This category includes: High-tech 1; Organic 1; Organic 2; Pesticide-free 2; Conventional 2.
Low input: the only organic residues going into the soil are from passive processes: decomposing fruit, roots and leaves. Includes: High- tech 2; Pesticide- free 2; Conventional 1.
At 0-5 cm depth, the average amount of organic carbon was 1.6 times higher in orchard soils under the high input carbon soil management group than under the low input group (Fig. 4.2).
Organic carbon (g C/kg soil)
18 16 14 12
4 2 0
Low C input
High C input
Fig. 4.2 Average (arithmetic mean) soil organic carbon from those orchards with low- and high-carbon input soil management, at depths of 0-5 cm and 5-10 cm, March, 1999. 4.3.3 Nitrogen Total soil nitrogen varied from 0.079 – 6.4 g/kg (79 to 6419 parts per million [ppm]) with an average of 1.13 g/kg (SD 1.22). As with carbon, the soil at 0-5 cm contained significantly more nitrogen than that at 5-10 cm (1.7 v. 0.5 g/kg; Fig. 4.3). Soil at depths of 5-10 cm at the edge of the rows had twice the nitrogen content of that at the middle (0.6 v. 0.3 g/kg), but there was no difference between edge and middle at 0-5 cm depth (data not shown). As with carbon, there was no pattern relating to management category of the properties (Table 4.1), but the nitrogen content reflected specific soil management practices (cf. below). Average soil nitrogen content on each property reflected average soil carbon content almost exactly (compare Figs. 4.1 and 4.3) - the lowest soil nitrogen content was at the Pesticide-free 1 orchard, the highest at the Organic 1 orchard - but carbon: nitrogen ratios were highly variable (average: 24:1, range 1.35:1 to 187:1; SD 24.2; data not shown).
Average 0-5 cm
Nitrogen (g N/kg soil)
Average 5-10 cm 4
Average 1-10 cm
3 2 1
Pe 2 stic ide -fre e1 Pe stic ide -fre e2
Or ga nic
Or ga nic
Co nv en tio na l1 Co nv en tio na l2 H igh Hi gh -te -te ch ch 1 Hi 2, gh A ldi -te ca ch rb 2, no Ald ica rb
Fig. 4.3 Average (arithmetic mean) soil nitrogen content at depths of 0-5 cm, 5-10 cm and 010 cm, March, 1999. Unlike organic carbon, most properties receive significant inputs of various nitrogencontaining fertilisers (cf. 3.1), although the nitrogen content of the different fertilisers, their application rates and, hence, the amount of molecular nitrogen input, varies dramatically between properties. There is no relationship between the amount of molecular nitrogen applied (kilograms per hectare per year) and soil nitrogen content (data not shown), suggesting that some other factor is important. Bearing in mind the relatively high capacity that the Riverland soils have for leaching, perhaps the relative solubility of nitrogen fertilisers may be an important factor. To investigate this, we categorised properties into two types based on the origin, solubility and plant-availability of their nitrogen fertiliser applications: •
Rapid-availability nitrogen: properties in this category predominantly use singlecompound nitrogen fertilisers of relatively high solubility, whereby the nitrogen is rapidly made available to plants. These include spray applications of urea and nitrate salts of ammonium, potassium and calcium, as well as NPK (10.4.4). This category includes: Conventional 1, High-tech 2 and Pesticide- free 1.
Slow-release nitrogen: properties in this category use predominantly nitrogen fertilisers of organic origin containing, diverse, slow-release nitrogen compounds. These include blood and bone, composted pig, cattle and poultry manure. This category includes: Conventional 2, High-tech 1, Organic 1 and 2 and Pesticide-free 2.
At both 0-5 cm and 5-10 cm depth, the average amount of nitrogen was significantly higher (2.1 and 1.7 times, respectively) in soils receiving applications predominantly of slow-release, low solubility nitrogen fertilisers than in soils receiving rapid-availability, high-solubility nitrogen fertilisers (Fig. 4.4).
Nitrogen (g N/kg soil)
2.5 2.0 1.5 1.117 1.0 0.5
0.0 High solubility N fertilisers Low solubility N fertilisers 0-5 cm
Fig. 4.4 Average soil nitrogen content at orchards receiving applications of rapid-availability, high-solubility nitrogen fertilisers and slow-release, low-solubility nitrogen fertilisers.
4.3.4 Phosphorous Total soil phosphorous varied from 0.1 – 1.9 g/kg (average 0.55 g/kg; SD 0.39). As with carbon and nitrogen, soil at 0-5 cm contained significantly more phosphorous than at 5-10 cm (0.72 v. 0.37 g/kg; Fig. 4.5). Soil at 5-10 cm at the edge of the rows had 1.4 times more phosphorous than at the middle (0.434 v. 0.308 g/kg), but there was no difference between edge and middle at 0-5 cm depth (data not shown).
Phosphorous (g P/kg soil)
Average 0-5 cm
Average 5-10 cm
Average 1-10 cm
0.8 0.6 0.4 0.2
Pe 2 sti cid e-f ree Pe 1 sti cid e-f ree 2
Or ga nic
Or ga nic
Co nv en tio na l1 Co nv en tio na l2 Hi Hi gh gh -te -te ch ch 1 Hi 2 gh ,A -te l dic ch arb 2, no Ald ica rb
Fig. 4.5 Average (arithmetic mean) soil phosphorous content at depths of 0-5 cm, 5-10 cm and 0-10 cm, March, 1999. As with carbon and nitrogen, there was no pattern relating to management category of the properties. Average soil phosphorous content on each property reflected average soil carbon and nitrogen content almost exactly (compare Figs. 4.1, 4.3 and 4.5; Table 4.1).
Unlike carbon and nitrogen content, phosphorous content did not reflect specific soil management practices Inputs of P-containing fertilisers are superphosphate (mainly calcium hydrogen orthophosphate, Ca(H2 PO4 )2 .H2O), phosphoric acid, urea phosphate, NPK, blood and bone, composted pig, cattle and poultry manure. There was no relationship apparent between soil phosphorous content and the levels of these inputs, or the relative solubility or plant availability of the phosphorous in the source material. The most likely explanation for this is incomplete reporting of phosphorous inputs: three growers reported no P inputs at all. 4.3.5 Sodium and Potassium Total soil sodium varied from 43 – 181 mg/kg (average 97 mg/kg; SD 31). Sodium in plantavailable form varied from 10 – 87 mg/kg (average 37 mg/kg; SD 16; Fig. 4.6). The average ratio of total soil sodium to plant-available sodium is 2.6:1. Total soil potassium varied from 873 – 2652 mg/kg (average 1612 mg/kg; SD 428). Potassium in plant-available form varied from 47 – 528 mg/kg (average 195 mg/kg; SD 16). The average ratio of total soil potassium to plant-available potassium is 8.3:1 (Fig. 4.6). The pattern of soil sodium on each property mirrors those for carbon, nitrogen and phosphorous (i.e. those with low C, N and P also tend to have low Na; Table 4.1). The levels of soil potassium deviate slightly from this pattern, and there is no clear correlation with potassium-containing fertiliser inputs, although high levels of plant-available soil potassium at High-tech 1 may reflect heavy inputs of potassium-rich poultry manure. As with carbon and nitrogen, there is significantly higher plant-available potassium at those orchards where slow-release, low-solubility organic fertilisers are applied, compared with those where highsolubility inorganic potassium-containing fertilisers are used (data not shown). 10000
Sodium (mg Na/kg soil)
140 120 100 80 60 40
Potassium (mg K/kg soil)
1 Co nv en Co tion nv al 1 en tio n Hi gh Hi al 2 -te gh Hi c gh -te h 2, tech ch Ald 1 2, no icarb Ald ica rb Or ga nic 1 O Pe rga sti cid nic Pe e-fre 2 sti cid e 1 efre e2
Co nv en Co tiona l nv en 1 tio n Hig H al 2 h Hi -tec igh-t gh h2 ec -te h1 ch , Ald ica 2, rb no Ald ica rb Or ga nic 1 O rg Pe stic anic ide 2 Pe -free stic 1 ide -fre e2
Fig. 4.6. Average total and available soil sodium (left) and potassium (right), March, 1999 4.3.6 Calcium and Magnesium Total soil calcium varied from 448 – 5860 mg/kg (average 1794 mg/kg; SD 1391). Calcium in plant-available form varied from 225 – 3348 mg/kg (average 1139 mg/kg; SD 713). The average ratio of total soil calcium to plant-available calcium is 1.6:1 (Fig. 4.8). Total soil magnesium varied from 122 – 2123 mg/kg (average 1079 mg/kg; SD 291). Magnesium in
plant-available form varied from 47 – 844 mg/kg (average 244 mg/kg; SD 122; Fig. 4.8). The average ratio of total soil magnesium to plant-available magnesium is 4.4:1. 4000
2500 2000 1500 1000 500
1 Co nv en Co tiona nv l en 1 tio n Hi al g 2 H Hi h-tec ighgh t e h c -te ch 2, A h 1 ld 2, no icar Ald b ica rb
Or ga nic Or 1 Pe g stic anic ide 2 Pe -free stic 1 ide -fre e2
Co nv en t Co iona l1 nv en tio na Hi Hi l 2 gh gh -t Hi -te gh ech ch 2, -te Ald 1 ch 2, no icarb Ald ica rb
Or ga nic 1 Pe Orga stic nic ide 2 Pe -fre stic e 1 ide -fre e2
Magnesium (mg Mg/kg soil)
Calcium (mg Ca/kg soil)
Fig. 4.7 Average total and available soil calcium (left) and magnesium (right), March, 1999. 4.3.7 Manganese and Copper Total soil manganese varied from 36-343 mg/kg with an average of 94 mg/kg (SD 47). Manganese in plant-available form varied from 3.8-19 mg/kg (average of 8.2 mg/kg; SD 2.9; Fig. 4.8). The average ratio of total soil manganese to plant-available manganese is 11.4:1. Total soil copper varied from 1.8-189 mg/kg (average 34 mg/kg; SD 30.6). Copper in plantavailable form was very scarce. Only 6 of 108 soil samples contained any plant-available copper (average 0.7 mg/kg), all from High-tech 2, Aldicarb and High-tech 2, no Aldicarb. 140
Copper (mg Cu/kg soil)
100 80 60 40
30 20 10
0 Co nv en t Co iona l1 nv en tio na l2 Hi Hi gh g Hig -tech h-tec h h-t 2, ec Ald 1 h2 i c a ,n o A rb ldic arb Or ga nic 1 Or ga Pe n stic ic 2 ide Pe -free stic 1 ide -fre e2
Or ga nic 1 Or ga Pe n stic ic 2 ide Pe -fre e stic ide 1 -fre e2
Co nv en ti Co onal 1 nv en tio na Hi l2 Hi gh g h tec -te Hi h2 c gh -te ,A h1 ch ldic 2, no arb Ald ica rb
Manganese (mg Mn/kg soil)
Fig. 4.8. Average total and available soil manganese (left) and copper (right), March, 1999.
4.3.8 Iron and Zinc Total soil iron varied from 4.0-9.3 g/kg (average 6.3 g/kg (SD 1.2). Iron in plant-available form, like copper, was very scarce (Fig. 4.9). Only 7 of 108 soil samples contained any plantavailable iron (average 0.6 mg/kg), at High-tech 1, Pesticide- free 2, and Organic 1. Total soil zinc varied from 10-276 mg/kg (average 63 mg/kg; SD 25; Fig. 4.9). Zinc in plant-available form varied from 0.07-16.1 mg/kg (average 3.3 mg/kg (SD 2.01). The average ratio of total soil zinc to plant-available zinc is 19.1:1. 9000
80 Zinc (mg Zn/kg soil)
6000 5000 4000 3000 2000
70 60 50 40 30 20
0 Co nv en Co tiona l nv en 1 tion al Hi gh Hig 2 h-t t Hi ec gh ech h 2 -te ch , Ald 1 ica 2, no rb Ald ica rb
0 Or ga nic 1 Or Pe g stic anic ide 2 Pe -free stic 1 ide -fre e 2
Co nv en Co tiona l nv en 1 tion a Hi gh Hi l 2 Hi -tec gh-te gh h2 ch -te ch , Ald 1 ica 2, rb no Ald ica rb
Or ga nic Or 1 Pe g stic anic ide 2 Pe -fre stic e 1 ide -fre e2
Iron (mg Fe/kg soil)
Fig. 4.9 Average total and available soil iron (left) and zinc (right) March, 1999. 4.4 Discussion The soils are characterised by the following features: •
an almost total lack of plant-available copper and iron, despite common and regular use of copper oxychloride as a fungicide);
low levels of available manganese and zinc, despite regular nutrient sprays of manganese sulphate and zinc sulphate;
relatively low levels of organic carbon (except in Organic 1 and Pesticide-free 2), although levels are higher than those of Mallee soils under dryland wheat production.
The scarcity of plant-available copper (average 0.7 mg/kg), despite the high inputs suggests it becomes bound to clay or humic particles or it leaches below the root zone. It would be worthwhile in the future to clarify the fate of copper in these soils, as well as to compare the soil concentrations with those from foliar analyses. In Section 3.5.1, mention was made of the potential risk of accumulation of manganese, copper and zinc to levels that may pose a toxicity threat to citrus trees. At current levels, this risk is probably low. Average plant-available zinc is 3.3 mg/kg. Levels >4 mg/kg are deemed
adequate for intensive crops in South Australian soils (cited by Armour and Brennan, 1999). Average plant-available manganese is 8.2 mg/kg, which is below most critical toxicity values cited by Uren (1999). Toxic levels (mg/kg) for citrus, as assessed by leaf analysis, are copper >15; zinc and manganese >300 (Robinson et al., 1997).
Carbon inputs Carbon (organic) soil content Nitrogen inputs Nitrogen (total) soil content Phosphorous inputs Phosphorous (total) soil content Potassium inputs Potassium (available) soil content Sodium inputs Sodium (available) soil content Calcium inputs Calcium (available) soil content Magnesium inputs Magnesium (available) soil content Manganese inputs Manganese (available) soil content Copper inputs Copper (total) soil content Iron inputs Iron (total) soil content Zinc inputs Zinc (total) soil content Average ranking, inputs Average ranking, soil nutrient content
Table 4.1 Summary of rankings of each orchard by nutrient inputs (Chapter 3) and concentrations of soil nutrients.
6 6 3 3 5 3 6 6 6 3 7 6 8 3 8 5 4 3 6 2 8 2 7 3
5 7 8 7 6 7 8 5 5 4 5 5 4 6 4 6 1 6 3 6 7 7 5 7
3 3 6 4 3 6 7 1 3 6 3 1 3 7 5 1 2 5 4 3 3 8 3 4
6 4 7 6 8 4 2 8 6 5 8 8 7 2 7 8 6 1 7 4 6 1 8 5
1 1 1 1 4 1 1 2 1 1 2 2 2 1 1 4 3 2 2 1 2 5 1 1
2 5 5 5 1 5 5 3 4 6 1 3 1 5 6 7 8 7 1 8 1 3 2 6
6 8 4 8 7 8 3 7 6 8 4 7 5 8 3 2 7 8 7 7 5 5 6 8
4 2 2 2 2 2 4 4 2 2 6 4 6 4 2 3 5 4 5 5 4 4 3 2
Soil organic carbon is markedly higher in the top 5 cm of soil than in the 5-10 cm fraction (Fig. 4.1). Soil structure, nutrient and water holding capacity, soil biodiversity and spatial arrangement of citrus roots would be improved if organic carbon levels could be increased throughout the profile, but particularly below 5 cm. This can be done using various organic amendments, establishment of perennial ground cover of grasses and herbs that are then cut and used for mulch, green manure cover crops, or a combination of these. The advantage of managing organic matter content through the use of ground cover is that it provides habitat for beneficial invertebrates.
Chapter 5. SOIL BIOLOGY: NUTRIENT CYCLING AS AN ECOSYSTEM SERVICE 5.1 Introduction The soil interacts with plants and the environment to effect the transformation, flow and accumulation of energy and matter. As such, a primary ecosystem function, or “service”, is the supply of nutrients to plants through the major biogeochemical processes and elemental cycles (carbon, nitrogen, phosphorous and sulphur). Thus soil provides the foundation for all terrestrial ecosystems involving higher plants. Other functions are embodied in properties such as resilience (i.e. the capacity of an ecosystem to tolerate perturbation) and its relevance to control of pests and diseases; soil structural characteristics, the role of soil in the storage and filtration of water and as a carbon sink. Soil biota (principally bacteria, fungi, actinomycetes, algae, protists and invertebrates) is vital to the biogeochemical functioning of environmental systems. The Prime Minister's Science Engineering and Innovation Council document ‘Underpinning Natural Resource Management with Science and Technology Innovations’, (PMSEIC, 1999) clearly highlighted the key role of soil biota in maintaining ecosystem processes and functions: ‘[Soil organisms] contribute to soil fertility and agricultural productivity but are critically threatened by agricultural practices and are being lost’. Similar arguments apply to the function and importance of these biological elements in native, or ‘natural’ terrestrial and aquatic ecosystems within agricultural landscapes that are impacted upon by agricultural practices. However, whilst we recognise the importance of biogeochemical processes in maintaining functional and ecological integrity in environmental systems, the links between our understanding of the behaviour of biological elements and our ability to model, predict and manage biogeochemical processes is far from comprehensive. Perhaps the greatest challenge facing us is the definition of the role of biodiversity in maintaining biogeochemical process function. Is there an optimum biodiversity that needs to be maintained in order to ensure continued process? Is there, in fact any relationship between biodiversity and function/process? A recent article by Copley (2000) in Nature discusses the recognition by ecologists that the functioning of terrestrial systems depends on soil biological activity and biodiversity. The issue of defining the links between biodiversity and biogeochemical process is of immense debate internationally. Wardle and Giller (1997) note that the relationship between the productivity of soil organisms and population diversity is unclear. Bengtsson (1998) went as far as to say that there is no mechanistic relationship between diversity and soil ecosystem function, and that correlations between diversity and function in soils will be non causal. Therefore, the link between the diversity of organisms carrying out key biogeochemical transformations in environmental systems is a critical knowledge gap in our current understanding. There are two extreme scenarios in the relationship between biodiversity, biogeochemical function and sustainable production: (1) High functional diversity results in greater productivity; more rapid ecosystem processes, greater stability and resilience; or (2) There is no mechanistic relationship between diversity, productivity and resilience. If scenario (1) is correct, then the promotion of management practices designed to maintain and enhance functional diversity becomes the cornerstone of agricultural practice. However if scenario (2) is the case, then the management of diversity is virtually irrelevant as a production management strategy, and is only important in terms of the intrinsic value of biodiversity conservation. There are significant socio-economic and natural resource implications for Australian agriculture in failing to address this issue (as we have done so far). To adopt
management practices based on the belief that soil biodiversity is important when it is not is equally as wasteful as to squander the free goods and services provided by the biological activity of soil organisms if the converse is true. This chapter is concerned with understanding patterns and processes of the biota in soils under citrus. We do not have the capacity within the scope of this project to include consideration of all soil biota, and have focussed on invertebrates, particularly nematodes and arthropods. The first task was to construct a food web for soils under citrus in order to provide a basic conceptual model of nutrient and energy pathways. By comparing diversity and abundance of each functional group (i.e. feeding type: predators, fungal feeders and so forth) in the food web, we can gain a quantitative comparison between the soils of different properties that may be attributable to management practices. 5.2 Nematodes The abundance and diversity of nematodes was investigated in a study conducted by Dr Mike Hodda (CSIRO Entomology). The original intention was to sample nematodes contemporaneously with other soil arthropods, i.e. every quarter. However, the very high time demand of sorting, mounting and identifying nematodes from soil samples required that sampling be limited to November 1998 and May, 1999. Nematodes are among the most common multicellular organisms in all soils. Different nematodes feed on a wide range of different foods and thus play different ecological roles: from piercing plant roots, or diverting plant resources and reducing plant growth, to stimulating microbial productivity through grazing on bacteria, to preying on other soil animals, to consuming fungal hyphae, to parasitising harmful insects. The abundance and diversity of these different functional groups can be affected considerably by the way the soil is managed, which in turn can affect the way the soil ecosystem functions. Likewise, the other components of the soil ecosystem can influence the abundances of the different functional groups of nematodes. The relative and absolute abundances of different functional groups, or feeding types, are referred to herein as trophic structure. We compare trophic structure between orchards; between soils under the tree skirt and the mid-row, and between the two sampling occasions. 5.2.1 Methods Each of the 8 orchards, totalling 11 management regimes (including Valencia oranges at Conventional 1 Orchard), was sampled twice, in November 1998 and May 1999, over a single day. On each sampling occasion, 2 composite samples were taken from under the tree skirt and 2 composite samples were taken from the mid-row area. Each composite sample consisted of a subsample of approximately 400g taken from a bucket containing well mixed soil obtained from 25 cylindrical soil cores of diameter 21mm and depth 300mm, which were taken at haphazardly selected locations within the sample area. The sample of soil was weighed on return to the laboratory for calculation of abundance. Samples of 400g were fixed in the field and transferred to the laboratory for extraction of the nematodes, which was by centrifugal flotation (Hodda and Bloemers 1995). All extracted nematodes were counted and a systematic search of the first 100 individuals was used to estimate the proportion of each trophic group. The trophic groups used were those of Yeates et al. (1993). Most of these trophic groups are self explanatory, with the exception of the type "substrate feeders", which feed on small organic particles suspended in the soil water solution.
9 8 7 6 5 4 3 2 1 0
Or ga Pe nic stic 2 ide -fre e1 Pe stic ide -fre e2
Or ga nic
9 8 7 6 5 4 3 2 1 0
Co nv en tion al 2 H Hi i g gh h-t -te ec ch h1 Hi 2, gh Ald -te ch ica rb 2, no Ald ica rb
Nematodes m-2 (millions)
Or ga nic Pe 2 stic ide -fre e1 Pe stic ide -fre e2
Or ga nic 1
Co nv en tio na l1 ,v al. Co ,n nv oA en ldic tion arb a l 1, Co nv va en l., A tion ldic al arb 1, na v., Ald ica rb Co nv en tion al 2 Hig Hig h-t ec h-t h1 ec h2 Hig ,A h-t ldic ec arb h2 ,n oA ldic arb
Nematodes m-2 (millions)
1 Or ga Pe nic stic 2 ide -fre e Pe 1 stic ide -fre e 2
Nematodes m (millions)
Co nv en tio na l1 ,v Co al. ,n nv oA en tio ldic na arb Co l1 ,v nv al. en ,A tio ldic na l1 arb ,n av ., A ldic arb
Or ga nic
Co nv en tio na l1 ,v Co al. ,n nv oA en tio ldic n al Co arb 1, nv va en l . , tion Ald al ica 1, rb na v., Ald ica rb Co nv en tio na l2 Hi Hi gh gh -te -te ch ch Hi 1 2 gh ,A -te l dic ch arb 2, no Ald ica rb
6 Under trees
Fig. 5.1 Effect of location on total nematode abundance, November 1998
Fig. 5.2. Effect of location on total nematode abundance, May, 1999
Fig. 5.3 Effect of time of sampling on total nematode abundance under skirts of trees
nematodes m-2 (millions)
4 3 2 1
Pe 2 sti cid e-f ree Pe 1 stic ide -fre e2
Or ga nic
Or ga nic
Co nv en tio na l1 ,v Co al. ,n nv oA en ldic tio na arb Co l1 ,v nv a en l., A tio ldic na l1 arb ,n av ., A ldic arb Co nv en tion al 2 H igh Hi gh -te -te ch ch 1 Hi 2, gh Ald -te ica ch rb 2, no Ald ica rb
Fig. 5.4 Effect of time of sampling on total nematode abundance in mid-row 5.2.2 Results and Discussion
Nematodes m- 2 (millions)
Total abundance of nematodes was generally lower in the mid-rows than under the trees (Figs. 5.1 and 5.2). However, many of the differences were small. They were large only at the Pesticide- free 2 and Conventional 1 orchards. The exception was the Organic 2 orchard, where total abundance was substantially higher between the rows of trees. In this orchard, there were large numbers of bacterial feeding nematodes, possibly related to the decomposition of the excreta from the geese which roamed the orchard, and the geese droppings may have been deposited preferentially between the trees rather than in the rows. There were few differences in distribution of individual trophic types relative to the trees (Figs. 5.5-5.9). Nematodes feeding on fungal hyphae were more abundant under trees than between rows in all orchards except the two High-tech 2 sites (Fig. 5.7). This trophic group of nematodes is often more abundant in wetter soils, and the soil underneath the trees may dry less than that exposed between the rows. The reason for the opposite result at High-tech 2 is unclear. 0.6 Under trees (Nov) 0.5 Under trees (May) 0.4 Mid-row (Nov) 0.3 Mid-row (May) 0.2 0.1
Fig. 5.5 Abundance of nematodes that feed on plant roots.
Or ga nic Pe 2 sti cid e-f ree Pe 1 stic ide -fre e2
1 Or ga nic
Co nv en tio na l1 ,v Co al. ,n nv oA en tio ldi na ca Co rb l1 ,v nv al. en , A tion ldic al arb 1, na v., Ald ica rb Co nv en tion al
2 Hi gh Hi gh -te -te ch ch 1 Hi 2 ,A gh ldic -te ch arb 2, no Ald ica rb
Fig. 5.8 Abundance of predatory nematodes
1 Or ga Pe nic stic 2 ide -fre e1 Pe sti cid e-f ree 2
Or ga nic
Co nv en tion al 1, va Co l., n nv oA en ldic tio n arb Co al 1, nv va en l., A tio na ldic l1 arb ,n av ., A ldic arb Co nv en tio na l2 Hi Hi gh gh -te -te ch ch Hig 1 2 , h-t A l dic ec h2 arb ,n oA ldic arb
Nematodes m-2 (millions)
1 Or ga nic Pe 2 sti cid e-f ree Pe 1 stic ide -fre e2
Or ga nic
Co nv en tio na l1 ,v Co al. ,n nv oA en tio ldic n arb Co al 1, nv va en l., A tion ldic al 1, arb na v., Ald ica rb Co nv en tion al 2 H Hi i g gh h-t -te ec ch h1 Hi 2, gh Ald -te ica ch rb 2, no Ald ica rb -2
Nematodes m (millions)
1 Or ga Pe nic stic 2 ide -fre Pe e 1 stic ide -fre e 2
Or ga nic
Co nv en tio na l1 ,v Co al. nv ,n en oA tio ldic na Co arb l1 nv , v en al. tion ,A ldic al 1, arb na v., Ald ica rb Co nv en tio na l2 Hi Hi gh gh -te -te ch ch Hi 1 2, gh Ald -te ch ica 2, rb no Ald ica rb
-2 Nematodes m (millions)
Under trees (Nov) Under trees (May) Mid-row (Nov)
1.5 1 Mid- row (May)
Fig. 5.6 Abundance of nematodes that feed on bacteria. 1.2
Under trees (Nov)
Under trees (May)
Fig. 5.7 Abundance of nematodes that feed on fungal hyphae
2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 Under trees (Nov)
Under trees (May)
Under trees (Nov) Under trees (May) Mid-row (Nov)
Pe stic 2 ide -fre e1 Pe sti cid e-f ree 2
Or ga nic
Or ga nic
Co nv en tio na l1 ,v Co al. ,n nv oA en tio ldic n Co al arb 1, nv va en l ., A tion ldic al 1, arb na v., Ald ica rb Co nv en tion al 2 Hi Hi gh gh -te -te ch ch Hi 1 2, gh Ald -te ica ch rb 2, no Ald ica rb
Nematodes m-2 (millions)
2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0
Fig. 5.9 Abundance of omnivorous nematodes In general the abundances of all nematodes and individual trophic types were similar at both sampling times. The relationship between the total nematode abundances at the different orchards was similar in November and May (Figs. 5.3 and 5.4). There was no consistent trend of increase or decrease between the sampling times. The Organic 1 orchard always had the greatest total abundance of nematodes (Figs. 5.1 and 5.2). This orchard also had the greatest abundance and most even distribution of all trophic types (Figs. 5.5-5.9). It would be interesting to know whether the increased activity of beneficial soil nematodes compensates for the greater abundance of those feeding on plant roots. Of course, some of these nematodes may be feeding on the roots of plants other than the citrus trees. The differences in the abundances of the nematodes feeding on plant roots with different management types was not great relative to that seen in many situations where plant-parasitic nematodes are causing major losses. In these cases, differences in abundance of more than ten-fold are common, whereas the maximum difference observed in this study was about fourfold. There was also great variability between the samples taken under the trees and between the rows, between different sampling times, and between different orchards with similar management regimes. The two replicate samples, being taken from large volumes of soil taken over a wide area from many cores, were generally similar. The Organic 2 and Pesticide- free 2 orchards had the second highest total abundances, but the distribution of trophic types was different. Nematodes feeding on hyphal fungi were abundant at the Pesticide-free 2 orchard, but not at the Organic 2 orchard, and the abundances of bacterial feeders, carnivores and omnivores was much more variable (Figs. 5.5-5.9). In this respect the organic orchards were different: Organic 1 and Organic 2 orchards had high abundances of bacterial- feeding nematodes, but the Conventional 2 orchard did not (Fig. 5.6). The abundances of bacterial feeding nematodes at the Pesticide- free 2 and Pesticide- free 1 orchards ("pesticide free") were also in general higher than the other orchards, but lower than the Organic 1 and Organic 2 orchards, although there was some variation with time of sampling and location (Fig. 5.6). The Organic 1 and Conventional 2 orchards were the only ones, which had "substrate" feeding nematodes present in detectable numbers. During recent studies on wheat fields in southern NSW, this trophic group was found to be a useful indicator of soil conditions (Hodda
et al.1999). This trophic group feeds on organic material suspended in soil water, and it could be indicative of a soil system with more water- holding capacity or more forms of organic matter than soil systems without it. The lowest total abundances of nematodes were at the orchards where Temik (Aldicarb) was used: High-tech 2, Aldicarb and Conventional 1, val., Aldicarb (Figs. 5.1 and -5.2). The abundances of most trophic groups were less than at the adjoining orchards that did not have Temik applied (High-tech 2, no Aldicarb and Conventional 1, val., no Aldicarb). The abundances of nematodes feeding on plant roots was generally lower in Temik-treated orchards, but not always, and the difference with Temik was greater at High-tech 2 than at Conventional 1 (Fig. 5.5). The orchards with Temik applications had very small numbers of predatory nematodes (Fig. 5.8). Organic 1 had the greatest abundance of predators, with Organic 2, Pesticide- free 2, Pesticide-free 1 and Conventional 2 next and slightly greater than the others. In general the abundance of predators was correlated to the abundance of other nematodes. 5.2.3 Conclusions Overall, the different management regimes seem to result in different trophic composition of soil nematodes. The "organic" orchards, particularly the Organic 1 orchard and to a lesser extent the Organic 2 orchard, have the greatest abundance of most trophic types. In general this should indicate that the soil ecosystem is diverse and active in supplying the nutritional needs of the plants. The pathways of energy and nutrient flows from the surface, through the soil and to the plant roots involve bacteria and fungi in a variety of microhabitats (hence the presence of "substrate" feeders). The down side is that these orchards also tend to have the greatest abundances of nematodes feeding on plant roots, which consume photosynthates, which would otherwise be available to the plant. Whether the contributions of the beneficial nematodes outweigh that of the harmful ones is beyond the scope of the present study. By way of contrast, the Conventional orchards tend to have much lower abundances of all trophic groups of nematodes, as well as a soil system that might operate differently because of greater direct inputs. The potential advantage of this type of system may be that the abundances of the nematodes feeding on plant roots are lower than in the other systems. The potential disadvantage is that low-diversity systems tend to be less resilient and delivery of ecosystem services (such as nutrient cycling) tends to be poor (Chapter 2). It is worth noting that the above results refer to trophic groups as a whole, and that there can be considerable variation in the activities within these broad groups. For example, the nematodes feeding on plant roots included Tylenchulus semipenetrans (the citrus nematode), Xiphinema spp. (dagger nematodes), and nematodes from the suborder Criconematina (the ring and sheath nematodes). All these nematodes are known economic pathogens of citrus. Other nematodes in the trophic group of plant-root feeders, which were also present, such as Tylenchus spp. and Boleodorus spp., almost certainly cause less damage to citrus trees. 5.3 Arthropods 5.3.1 Methods Plots of 40-50 year-old Washington navel orange trees were selected for study. At each orchard, three alternate rows were chosen for repeat sampling using 5 x 5 cm diameter soil cores (i.e. of six rows, numbers 1, 3 and 5 were sampled). A stratified random sampling regime was used, with cores taken from the edges (under the skirt of the trees) and middle of
the rows, each to a depth of 10cm, in 2 x 5cm fractions). Steel corers (made from lengths of scaffold pipe) were thrown by hand a random distance down each row and cores taken at 0-5 cm and 5-10 cm from the edge and from the middle of the row (i.e. 4 cores per sampling point). The corer was then thrown again and the process repeated, a total of 5 times per row, making a total of 20 samples per row, and 60 per orchard on each sampling occasion. An additional aim was to examine the effects of the nematicide Temik (Aldicarb) on nontarget soil fauna, about which there was some debate amongst the growers. To this end, two sites were sampled at the High-tech 2 orchard. One had been treated with Temik and another was untreated. Also at Conventional 1 orchard a treated and an untreated site were chosen amongst Valencia plantings. This site was sampled only on the first occasion. The Washington navel site at this orchard had also been treated with Temik. Soil cores were extruded into plastic snap-top bags, labelled, stored in an ice-box, transported to the laboratory within 36 hours of sampling, and the arthropods extracted using a modified Tullgren funnel apparatus in a temperature-controlled glasshouse for 7-10 days. Samples were hand-sorted, mounted on microscope slides, counted and identified to various taxonomic categories (Table 5.1) under a stereobinocular microscope or a compound microscope. Results are expressed as numbers per soil core. The conversion factor for numbers per square metre is 509 (i.e. the number of cores that would fit into a square metre: area of soil core = 2πr2 = 19.63 cm2 divided into the number of cm2 in 1 m2 , i.e. 10,000). 5.3.2 Results and Discussion
Total arthropods in 60 x (5 cm diameter) soil cores
Abundance: Some 145,661 soil arthropods were extracted from 2390 sample soil cores taken on four, quarterly sampling occasions during 1998/1999. The samples were collected by Matt Colloff and Geir Fokstuen. The arthropods were extracted, sorted and identified by Geir Fokstuen (with occasional checks on identities by Matt Colloff). Abundance of soil arthropods was greatest in the top 5 cm of soil. In August 1998, the 510cm cores contained an average of only 14% (range 10-21%) of the total arthropod abundance. Abundance was not significantly higher at the edge of the row (under the skirt of the trees) compared with the middle (total arthropods, edge v middle, Aug. ’98: 40,434 v. 39,936; Dec. ’99: 22,886 v. 11,231; Mar., ’99: 5,533 v. 4,208; Aug., ’99: 6,832 v. 14,511).
Conventional 1, nav., Aldicarb Conventional 2
High-tech 2, Aldicarb
5000 High-tech 2, no Aldicarb 4000 Organic 1
Pesticide-free 2 August, 1998
Fig. 5.10 Seasonal variation in abundance of soil arthropods – edge of rows
Conventional 1, nav., Aldicarb
Total arthropods in 60 x (5 cm diameter) soil cores
High-tech 2, Aldicarb
High-tech 2, no Aldicarb
2000 Organic 2
1000 Pesticide-free 1
0 August, 1998
Fig. 5.11 Seasonal variation in abundance of soil arthropods – middle of rows The abundance of soil arthropods was much lower during the hottest half of the year (Figs. 5.10 and 5.11). Some 80,460 individuals were found in 660 samples in August, 1998; 34,117 from 580 samples in December, 1998; 9,741 from 580 samples in March, 1999 and 21,343 from 580 samples in August, 1999. There is a seven- fold difference in average numbers per sample between August 1998 and March, 1999 (122 per core v. 17 per core, respectively). There was no clear relationship between abundance and management type. The average number of arthropods per sample over the entire period varied from 131 at Organic 1 to 14 at High-tech 2 – no Aldicarb (Fig. 5.12). There was a slight association between ranking of orchards by arthropod abundance and ranking by nutrient inputs and soil nutrient content (Table 4.1, Fig. 5.12). However, the closest association is with soil organic carbon (Fig. 5.13), which accounts for 29.4% of the variation in arthropod abundance, compared with 7.7% for soil nitrogen and 3.8% for soil phosphorous (data not shown). 1 1
140 120 100 80 60 40 20
2 Pe Co sti nv c ide en tion -fre al e 1, 1 na v., Ald ica rb Hi gh -te ch 2no Al dic ar b
O rg an ic
2, Al dic ar b
Hi gh -te ch 1
Hi gh -te ch
2 Pe sti cid efre e
Co nv en tio na l2
0 O rg an ic1
Average number of arthropods per soil core
Soil nutrient input Soil nutrient content
Fig. 5.12 Abundance of soil arthropods ranked according to orchard management type, and showing rankings of soil nutrient inputs and soil nutrient content (cf. also Table 4.1).
Mean Morphospecies Diversity of Soil Arthropods
Mean Abundance of Soil Arthropods
Percentage Soil Organic Carbon
Percentage Soil Organic Carbon
Fig. 5.13 The relationship between soil organic carbon (%) and mean abundance of soil arthropods (left) and mean taxonomic diversity (right) (per 5 x [5 cm diameter] soil cores) (graphed on log. scale). It could be perceived that soil C is dependent on arthropod abundance, since arthropods contribute C to the soil upon their death and decay. However, this is highly unlikely since arthropod biomass carbon averages only about 32 mg/kg soil, or a mere 0.3% of average soil organic carbon content. Taxonomic diversity: The taxonomic diversity of soil arthropods (i.e. the average number of taxa or morphospecies [c.f. Table 5.1] per sample) correlates with their abundance (R square = 0.57; data not shown). It was highest on average in August 1998 and lowest in March 1999 (Fig. 5.14). As with abundance, there was no clear relationship between taxono mic diversity and management type, but there was a close correlation with soil organic carbon (Fig. 5.13), which accounted for 42.6% of the variation in taxonomic diversity. Average taxonomic diversity was highe st under a ground cover of mixed grasses and herbs (3.8 taxa per sample) than under weeds (2.8) and lowest under weeds/bare soil (2.1) (Fig. 5.15). Thus, there is an association between quality of ground cover in the provision of habitat and the diversity of soil arthropods. In part, this is likely to be linked to the effect of well-developed swards of grasses and herbs in maintaining soil water content through minimising evaporation. Soil macropores, produced through death and decomposition of plant roots, provide important means of soil aeration, water infiltration and transport routes for soil arthropods. In essence, having a well-developed ground cover of diverse plants is likely to produce a spatially complex series of microhabitats that are available for colonisation.
Table 5.1. Taxonomic groups into which the soil arthropods were sorted, and the functional groups to which these taxa were assigned. See text for definitions of functional groups. Taxonomic group Enchytraeidae Isopoda Isoptera Diptera* Formicidae Other Hymenoptera Coleoptera* Lepidoptera* Hemiptera Thysanoptera Protura Diplura Symphyla Chilopoda Diplopoda Araneae Isotomidae Onychiuridae Brachystomellidae Entomobryidae Sminthuridae Hypogastruridae Mesostigmata Prostigmata
Common Name Enchytraeid worms Woodlice Termites Flies Ants Wasps Beetles Butterflies and moths Bugs Thrips Proturans Diplurans Symphylans Centipedes Millipedes Spiders Isotomid Springtails Onychiurid Springtails Brachystomellid Springtails Entomobryid Springtails Sminthurid Springtails Hypogastrurid Springtails Mesostigmatid Mites Prostigmatid mites
Moss Mites or Beetle Mites
Eupthiracarid Moss Mites) Astigmatid Mites)
Trophic or Functional Group Saprophages Saprophages Saprophages Saprophages Saprophages Predators and Parasitoids Saprophages Plant feeders Plant feeders Plant feeders Omnivores Predators and Parasitoids Saprophages Predators and Parasitoids Saprophages Predators and Parasitoids Fungivores Fungivores Fungivores Fungivores Fungivores Fungivores Predators and Parasitoids 25% each plant feeders, saprophages, fungivores, predators and parasitoids 33% each saprophages, fungivores, predators and parasitoids Fungivores Omnivores
Mean no. taxa in 60 x (5 cm diameter) soil cores
*Present in soils predominantly as larvae 8
Conventional 1, nav., Aldicarb
High-tech 2, Aldicarb
2 Pesticide-free 1 1 Pesticide-free 2 0 August, 1998
August, 1999High-tech 2, no Aldicarb
Fig. 5.14 Seasonal Variation in Taxonomic Diversity of Soil Arthropods
8.0 Mean no. taxa per sample
7.0 6.0 August, 1998
March, 1999 August, 1999
W ee ds W ee ds /ba re so il W ee ds /ba re so il
W ee ds
W ee ds
M ixe d
he rbs /gr as M se ixe s dh erb s/g ras M se ixe s dh erb s/g ras se M s ixe dh erb s/g ras se s
Fig. 5.15 Seasonal variation in taxonomic diversity in relation to ground cover. Left to right: Mixed grass/herbs = Pesticide-free 1, Organic 1, High-tech 1, Organic 2; Weeds: High-tech 2 +Aldicarb, Conventional 2, High-tech 2 no Aldicarb; Weeds/bare soil: Pesticide-free 1, Conventional 1. Functional Diversity: Table 5.1 details the functional groups that each of the arthropod taxa have been ascribed to. These are straightforward, with only two requiring definition. Saprophages feed off dead and decaying organic matter and parasitoids lay their eggs inside living arthropods, upon which the larvae feed after hatching. The purpose of dividing taxa into these categories is because they give some indication of the ‘job’ that each taxon does in the soil, whereas the taxon name alone provides no such information. If one knows which functional groups are represented, one can start to construct a food web (Fig. 5.16). A food web is a diagram of which organisms eat which other organisms. It provides a model of how nutrients and energy are moved and transformed, and of the relative complexity of the system under study. It serves as a map of community structure. An examination of the relative abundance of functional groups according to orchard management types can provide some indication of how the systems might be working or whether there is anything wrong with them. For example, a complete absence of predators/parasitoids may indicate that the system had been heavily perturbed or damaged, because predators tend to be more sensitive to disturbance than other functional groups.
Fruit and Flowers
Nematode -feeding Mesostigmatid Mites
Collembola Ectomycorrhizal Fungi
Mesostigmatid Mites General Predators
Roots Saprophytic Fungi
Nematophagous Oribatid Mites
Fig. 5.16 The basic soil food web of Riverland citrus orchards The average percentage composition of the functional groups of soil arthropods is given in Fig. 5.17, and the seasonal variation in Fig. 5.18. There is no correlation between the proportions of each functional group and the orchard management category. Overall, there is a relatively high proportion of fungal feeders (average 68% of total arthropod population) compared with saprophages (11%; a category which will overlap somewhat with fungal feeders), predators/parasitoids (11%), omnivores (8%) and plant feeders (3%). It is noteworthy that bacterial feeding nematodes outnumbered fungal hyphal feeders ten to one (bacteriophages averaged 54% of the total nematode population, compared with 5.3% for fungal hyphal feeders; Figs. 5.6 and 5.7). We identified no arthropod taxa that were specialist bacterial feeders (although such specialists exist). These data suggests that the microbial saprophage component of the soil food web represents a balance between fungal and bacterial populations and that there is some form of food resource partitioning by the invertebrate fauna based on their body size. The microfauna are predominantly bacteriophagous, whilst the mesofauna and macrofauna are predominantly fungivo rous. There was little seasonal variation in composition of the functional groups, despite considerable variation in abundance (compare Fig. 5.18 with Figs. 5.10 and 5.1). This suggests the key factors driving abundance (be they soil temperature, moisture content, availability of food, or some other factor) impact similarly on each functional group. In other words, we found no evidence for greater sensitivity of, say, predators/parasitoids to population depression than, say, fungivores. This indicates that the food web, or community structure, is relatively resistant: it has a relatively high capacity to tolerate environmental change without changing to another state. This property is subtly different from resilience, which is the capacity of the system to return to its prior state after perturbation (Walker et al., 2002).
High-tech 2 Temik
High-tech 2 no Temik
Fig. 5.17 Average percentage composition of the functional groups of soil arthropods. Royal blue = plant feeders; brick red = saprophages; yellow = fungal feeders; light blue = omnivores; purple = predators. 80
Plant feeders Saprophages
Predators & Parasitoids
20 10 0 Aug-98
Fig. 5.18 Seasonal variation in average percentage composition of functional groups of soil arthropods.
Effects of Temik (Aldicarb): We could find no evidence that Temik use had a significant effect on the abundance or taxonomic diversity of soil arthropods (Figs. 5.15 and 5.16). In fact, abundance and diversity were higher on those plots where Temik was used at both Conventional 1 and High-tech 2 orchards. This compares with a slight (and not statistically
Total Arthropods in 60 x (5 cm dia.) soil cores
14000 Edge Total 12000 Middle Total
8000 6000 4000 2000
Hi gh -te ch 2
-n oT em ik
-T em ik Hi gh -te ch 2
1, no Te m ik Co nv en tion al
Co nv en tio na l
1, Te m ik
Fig. 5.19 Effects of Temik on abundance of soil arthropods Mean morphospecies diversity
7 Edge Total
Middle Total 5
4 3 2 1
-n oT em ik Hi gh -te ch 2
-Te m ik Hig h-t ec h2
Co nv en tin al 1, no Te m ik
Co nv en tin al 1, Te m ik
Fig. 5.20 Effect of Temik on taxonomic (morphospecies) diversity of soil arthropods. significant) lower abundance of nematodes in the Temik-treated plot compared with untreated plots (compare Columns 1 and 2, 6 and 7 of Figs. 5.1-5.7). It would appear that soils treated with Temik were neither less biodiverse, nor contained significantly fewer plant pathogenic nematodes than those not treated. In other words, we could find no significant non-target effect, but we could find no target effect either. Treatment with Temik costs farmers about $110 per hectare at 1999 prices. Average pesticide costs for the growers (including herbicides and fungicides) are $136 ha pa (Table 3.8).
5.4 Management of Soil Biodiversity as a Resource for Farmers Figure 5.21 shows the relationship between orchard management type and the abundance of soil arthropods expressed in terms of their biomass (i.e. their weight), and the dollar value of the nitrogen component of that biomass: put crudely, their worth as fertiliser. We found that there was an average variation between properties over the four sampling periods of $33 to $2 per hectare (range $76 to $1), giving us a useful insight into the variation between properties in relative soil invertebrate biomass and its capacity to provide nitrogen to the soil when that biomass died and decomposed. The reason for this histogram is to demonstrate the direct and immediate relationship between an ecological variable (i.e. population density) and an economic variable (i.e. dollar value of nitrogen). It follows that the management of soil biodiversity is an activity of significant economic relevance, no different from managing other assets. 10000 Biomass g/m-2 Nitrogen $/ha
Ins ec tici Hi de gh -fre -te ch e2 2No Ald ica rb
2 +A ldic arb Co C on nv en ve tion ntio al na 1+ l2 Ald ica rb 2
Or ga nic
Hig hT ec h2
Or ga nic
1 Hi gh Te ch Ins 1 ec tici de -fre e1
Fig. 5.21 Biomass of soil arthropods and their dollar value in nitrogen. August 1998. It should be pointed out that the dollar value of the nitrogen component of the soil biota does not represent the rate at which nitrogen is mineralised from plant residues by the soil biota and assimilated. Rather, it is a basic indicator of the value of the biota as a resource. A more sophisticated model would use estimates of the value of nutrient turnover and assimilation rates achieved by the soil biota. This was beyond the scope of the present study, but would provide farmers with a more accurate estimate of the dollar value of nutrient cycling as an ecosystem service. Other ways in which the activities of the soil fauna have a financial impact are through soil formation, aeration, increasing the capacity for water penetration and reducing the capacity for compaction. All of these are difficult to quantify because they are delivered over a long timeframe. Also, soil fauna contributes to pest control, the subject of the next chapter. Clearly, these benefits will not take place efficiently or effectively if the soil biota is neglected, or if management practices are used that have a detrimental effect.
Chapter 6. NATURAL ENEMIES OF KELLY’S CITRUS THRIPS: PEST CONTROL AS AN ECOS YSTEM SERVICE 6.1 The Problem - Kelly’s Citrus Thrips Kelly’s Citrus Thrips (spelled 'thrips' both singular and plural) is a major pest of increasing significance affecting over 1,000 growers in the Riverland and Sunraysia. It was first recorded there in 1935, but significant damage has occurred only in the past decade. Estimates of damage are not comprehensive, but approximately 20-40% of fruit can be rendered unsaleable to the quality fresh fruit market. In 2000, thrips damage rose dramatically. The outbreak was sufficiently severe that growers were using up to five applications of chlorpyrifos in order to attempt control. The average number of applications per orchard was estimated to be three, with application costs of about $150 per hectare and chemical costs of about $75 per hectare, covering some 3,670 ha of navel oranges in the Riverland and Sunraysia (G. Baker, personal communication, 2002), totalling nearly $2.5 million. Adult Kelly’s Citrus Thrips (Pezothrips kellyanus) are dark, elongated, about 2 mm long (Fig. 6.1). The juvenile, white-yellow in colour, is responsible for most of the dama ge to fruit early in the season; producing characteristic scarified halo- mark damage to the skin around the calyx (Mound and Jackman, 1998). Damage can cover up to 40% of the skin surface. The economic costs of Kelly's Citrus Thrips are thus due to the cost of control efforts as well as and the downgrading in fruit value due to the unsightly appearance of the skin. The quality of the fruit itself is not affected.
Fig. 6.1 Kelly’s Citrus Thrips (Pezothrips kellyanus). Photograph courtesy of Laurence Mound, CSIRO Entomology. There is an additional cost generated by the overuse of chlorpyrifos, stemming from the risk of generating more widespread resistance tha n already exists. Other environmental impacts resulting from greater applications of insecticides include soil contamination and detrimental effects on non-target, beneficial organisms. Soils in the Riverland are sandy and highly porous, so insecticides are easily leached through the soil profile and into the groundwater. Chlorpyrifos is the main insecticide approved for use against Kelly’s Citrus Thrips, so the risk of resistance cannot be reduced by using different insecticides alternately.
Fruit retailers seem to believe that blemished, thrips-damaged fruit is not saleable. But consumers might prefer to choose whether to buy blemished fruit from insecticide- free orchards, or cosmetically perfect fruit from orchards that use insecticides. The current lack of consumer choice is partly due to the perception that blemished fruit is of poor quality inside. This is not so. If consumers continue to demand fruit of perfect appearance, growers will have no option but to use insecticides to control insects that cause cosmetic damage. The economic effect is to increase production costs and cut farm profits. The most widely- used alternative to chemical control is integrated pest management (IPM.), which relies on combinations of biological control, host plant resistance, natural or cultural control (using factors such as weather or crop management techniques to disrupt pest populations), and pesticides (but only after monitoring of pest populations indicates their use is warranted). 6.2 Methods In late 1999, as a result of the increasing severity of thrips damage in the Riverland, we were asked by the citrus growers to investigate the relationship between soil biodiversity and the potential for control of Kelly's Citrus Thrips using natural enemies. At that time, there was no IPM strategy for Kelly's Citrus Thrips under development, and Riverland farmers had a choice between using chlorpyrifos or doing nothing. During discussions with the growers, it emerged that four of the properties at which we had sampled soil biodiversity (Chapter 5) were seriously affected and the other four were unaffected or had received only mild damage. This chance pairing of 'positive' and 'negative' groups provided an important starting point to our investigations, which were as follows: 1. A survey for previously documented natural enemies of Kelly's Citrus Thrips, specifically parasitoid wasps of the genus Spilomena. Three citrus orchards between Renmark and Loxton were sampled qualitatively for parasitic wasps by staff of the Hymenoptera Project, Australian National Insect Collection, in February, 2000, using yellow pan traps and sweep netting. 2. A retrospective analysis of the soil biodiversity data to search for differences between the two groups of properties; 3. An assessment of group-specific differences in management methods and orchard characteristics; 6.3 Results 6.3.1 Parasitoid wasps – Spilomena spp. Wasps belonging to the genus Spilomena (Hymenoptera: Sphecidae) are small (3-4 mm), darkly coloured thrips gatherers. The adults collect thrips larvae in their mouthparts, deposit them in their brood chambers to feed their young, and are thus, potentially, biocontrol agents of thrips. Some 9 species are described from Australia. There are about 2,000 specimens in the Australian National Insect Collection, including some collected from Bookmark Biosphere Reserve in 1995. Almost nothing is known of their taxonomy or their biology. There were three species among the collections made in February, 2000:
Spilomena sp. 1. Ca. 30 specimens collected, mostly from Melaleuca flowers and a few from citrus orchards. The locations were labelled "5 km W Renmark", "7 km W Loxton" and "Organic 2". This species is widespread in the Riverland and Mallee areas, west to the Eyre Peninsula. It seems to be fairly common in natural habitats, based on collections made by staff of the Australian National Insect Collection in 1992. Spilomena sp. 2. One female collected in an orchard 3 km east of Renmark. This is an unusual species with massively expanded genae. It is not known from previous collections. Spilomena sp. 3. About 8 specimens, none from citrus orchards (e.g. from 7 km west of Loxton, on Melaleuca flowers). This species is possibly conspecific with specimens in the Australian National Insect Collection from Amaroo. There are at least 20 species of unsorted Spilomena in The Australian National Insect Collection from the Riverland and Mallee areas, some common and others collected only once. 6.3.2 Soil Biodiversity Data On re-analysing soil biodiversity data according to whether properties had suffered thrips damage or not, we found the variable that differed most between the two groups was the size of the soil mite populations. The average total number of mites in our August, 1998 samplings was 1565 (range 1005-2262) in the 4 orchards infested with thrips, compared with 4912 (range 3892-5871) in the orchards with no thrips (Fig. 6.2). This is a highly statistically significant difference between the two groups and suggested there was an association between absence of thrips damage and high mite populations. 7000
(no. mites in 60 x [5cm x5cm] soil cores)
Mean total abundance
2000 1565 1000
Fig. 6.2 Abundance of soil mites at orchards with significant damage cause by Kelly's Citrus Thrips and those without, August, 1998. Numerals represent averages.
On checking the identity of the mites from the thrips-free properties, we found they comprised mostly predatory mesostigmatid species. We then compared the mean annual population density (average of the four sampling occasions) of mesostigmatid mites from those orchards with a thrips infestation and those without and found the average annual population density at thrips-affected orchards was 520 mites per square metre, compared with 4147 at thrips- free orchards, a difference of nearly eight-fold (Fig. 6.3). 6000
Mean no.mites per m m
1( NO Pe ) sti cid e-f re e2 (N O)
Or ga nic
Hig hT ec h1 (N O)
Co nv en tio na l2
1(Y ES )
2( YE S)
Pe sti cid e-f ree
Or ga nic
Co nv en tio na Hi gh l1 (Y Te ES ch ) .2 -A ldi Hi ca gh rb Te (Y ES ch .2 ) -N oA ldi ca rb (Y ES )
Fig. 6.3 Abundance of soil-dwelling predatory mesostigmatid mites in citrus orchards in relation to management type and whether they had significant thrips infestations ('YES') or not ('NO'). Some 17 species of mesostigmatid mites from the orchards have been identified by Dr Bruce Halliday, CSIRO Entomology. Some 4 or 5 are relatively common (Table 6.1; Appendix 7). In addition to the common species, each orchard appears to have an assemblage of rarer species, some of which are not found in other orchards. Considering the large area over which the orchards are scattered, combined with the very different patterns of management between orchards and resulting variation in ground habitat, this is not surprising.
Table 6.1 Species of predatory mesostigmatid mites from soil in citrus orchards, Riverland, South Australia Taxon Ascidae Antennoseius sp. A Antennoseius sp. B Arctoseius cetratus (Sellnick, 1940) Arctoseius sp. Asca sp. Protogamasellus mica (Athias-Henriot, 1961)
Protogamasellus massula (Athias-Henriot, 1961) Digamasellidae Dendrolaelaps sp. Laelapidae Hypoaspis sp. A Hypoaspis sp. B Ologamasidae Athiasiella relata (Womersley, 1942) Pachylaelapidae Pachylaelaps sp. Zygoseius sarcinulus Halliday, 1997 Parasitidae Pergamasus sp. Rhodacaridae Rhodacarellus silesiacus Willmann, 1936 Rhodacarus roseus Oudemans, 1902 Veigaiidae Veigaia pusilla (Berlese, 1916)
Walter, pers. comm., 2000
General predator, grassland soils, cosmopolitan. Used in biocontrol of sciarid flies General predator General predator Female parthenogen; general predator, (can also be reared on fungi); cosmopolitan; probably feeds on nematodes in citrus orchards Female parthenogen; general predator; Algeria and Florida
Walter & Ikonen, 1989 Binns, 1974; Walter & Lindquist, 1995
Walter, pers. comm., 2000
Very aggressive general predators – promising candidates for thrips control
Walter, pers. comm., 2000
Large, aggressive predators – promising candidates for thrips control; Australian endemic
Lee, 1973a; Walter, pers. comm., 2000
Nematode predator Phoretic on beetles; nematode predator; Australian endemic
Halliday, pers. comm., 2000 Halliday, 1997; Walter, pers. comm., 2000
Walter, pers. comm., 2000
Female parthenogen; nematode predator; cosmopolitan General predator; long generation time; Palaearctic
Lee, 1973b; Walter & Ikonen, 1989 Lee, 1973b; Walter, pers. comm., 2000
Female parthenogen; Collembola and mite predator; Georgia, North Carolina
Walter, pers. comm., 2000; Farrier, 1957
Walter, pers. comm., 2000 Walter, pers. comm., 2000 Walter & Ikonen, 1989; Walter & Kaplan, 1990; Halliday et al, 1998; Walter et al., 1993 Walter & Kaplan, 1990; Walter, pers. comm., 2000; Halliday et al, 1998
6.3.3 Orchard Characteristics The thrips- free properties tended to have inter-row ground cover consisting of fairly dense and diverse swards of perennial grasses and herbs, whereas those with a thrips problem had a mix of bare soil, annual weeds or a monoculture (eg. Lucerne) (Fig. 6.4). The species-rich, perennial, ground cover probably provides better habitat for predatory mites, as well as a reliable source of pollen, which many mesostigmatid mites use as a supplementary food source. Grasses tend to build up a thick layer of dead and decomposing shoot and root material above and below the soil surface. This organic layer is very effective at reducing evaporation from the surface of the soil, as well as providing protection to soil arthropods from desiccation.
Fig. 6.4 Examples of ground cover in four Riverland Citrus orchards. a = an example consisting predominantly of scant grasses, weeds and bare soil; b = patchy cover of lucerne and bare soil; c and d = perennial herbs and grasses, recently slashed.
6000 5150 4796
Mean no. mites m
W ee ds /ba re so W il ee ds /ba re so W il ee ds /ba re so W il e Pe ed re s/b nn ar ial es he oil rb s/g Pe ra re ss nn es ial he rb s/g Pe re ra nn ss es ial he rb s/g Pe ra re ss nn es ial he rb s/g Pe ra re nn ss es ial he rb s/g ra ss es
Fig. 6.5 Abundance of soil-dwelling predatory mesostigmatid mites in citrus orchards in relation to ground cover. 6.4 Discussion- Management of Natural Enemies and Conservation Biocontrol We have found an association in Riverland citrus orchards between perennial, ground cover and an absence of serious damage caused by Kelly's Citrus Thrips. It is important to emphasise that we have not proved that orchards with such ground cover will not suffer from thrips problems. Neither have we demonstrated that wherever such cover exists, it is swarming with natural enemies of Kelly's Citrus Thrips. However it is likely that abundant, diverse populations of natural enemies have a better chance of developing in this kind of cover than they will on bare soil/weeds or within monocultures. In Chapter 5 we reported an increase in taxonomic/morphospecies diversity associated with perennial ground cover (cf. 5.3.2, Fig. 5.15). If growers wish to make use of conservation biocontrol as an ecosystem service, then the presence of such cover is a pre-requisite. Recommendations concerning management of ground cover are outlined in Chapter 7. Natural enemies of thrips will be potentially important in a wide variety of horticultural produce, including cut flowers, tomatoes and strawberries, both within greenhouse and field settings. In citrus alone there are at least five thrips species of which four are important pests (Smith et al., 1997). The most important thrips pest of horticulture in Australia is the Western Flower Thrips, which has now been recorded in every state apart from the Northern Territory. Many horticultural systems lend themselves particularly to conservation biocontrol of insect pests because they are perennial-based systems, either in the crop-plants, associated non-crop vegetation, or both, and thus have a correspondingly high degree of spatial habitat variation, compared with annual cropping systems. The development and promotion of an effective integrated pest management system for Kelly's Citrus Thrips is currently the subject of research by entomologists at the South Australian Research and Development Institute (http://www.sardi.sa.gov.au/pages/entomolo/kctsumm.htm:sectID=4&tempID=5)
Chapter 7. CONCLUSIONS AND RECOMMENDATIONS In relation to soil ecology and sustainable citrus production, we found that soil biotic diversity was providing two valuable ecosystem services in the form of nutrient cycling and pest control. We have empirical evidence that the parameters associated with high diversity and abundance of soil invertebrates were soil organic carbon levels and the quality of habitat afforded by ground cover vegetation. Thus, the management practices required to encourage growth of biomass of the soil biota in order for it to deliver its ecosystem services are: •
Management of soil organic carbon levels. This means the addition of organic matter combined with periodic monitoring of changes in soil organic carbon levels. From the data in Fig. 5.13, at levels below about half a percent (5 g C/kg soil), abundance and diversity of soil invertebrates are likely to start to become limited by the availability of carbon, whereas at 2% (20 g C/kg soil), abundance and diversity of soil invertebrates are in the upper part of the range.
Provisio n of adequate habitat for natural enemies through management of ground cover of perennial grasses and herbs. This means planting an appropriate mix of species if no ground cover exists, or improving plant diversity if it consists of only a few species.
In fact, both of these management practices can be implemented in ways that are complimentary and have multiple benefits. For example, one of the simplest ways of adding organic carbon is through the addition of dead plant material. One way of doing this cheaply and easily is by slashing the herb layer and using it as mulch. Not only is organic matter added to the soil, but the mulching effect of the cut grass and herbs serves to reduce evaporation and retain soil moisture. This increases irrigation water-use efficiency as well as encouraging decomposition and mineralisation rates. The enhanced decomposition rates (decomposition progresses fastest in warm, damp conditions) will result in an increase in the depth of the organic horizon of the soil, through ingestion and conversion of plant residues into invertebrate faecal pellets, a process of reduction or breaking up into small fragments known as comminution. At Organic 1 orchard, which has received substantial organic matter inputs over the last 12 years, we have observed organic soil horizons of ca. 6 cm depth, compared with ca. 1 cm or less at other orchards. The process of comminution greatly increases the surface area-to-volume ratio of the plant residues. This enhances colonisation by fungi and bacteria that take decomposition to the next stage. Management practices that enhance decomposition processes also encourage further habitat diversity and complexity, which in turn encourages colonisation of a greater diversity and abundance of soil organisms. This example of a single management practice delivering resulting in several outcomes serves to highlight the inter-relatedness of different parts of the production system. It follows that the kinds of management practices most likely to result in sustainable production are those that deliver multiple benefits to different parts of the system. Ground cover management using permanent grasses and herbs and no tillage, also known as sod culture, or sward management, has been an established practice in Australian citrus production at least since the 1940s (Davidson, 1951). In some regions it is more common than others - it is not widely used in the Murrumbidgee Irrigation Area, for example. Some farmers are reluctant to use it because there have been concerns that the sward out-competes the citrus trees for nutrients and water (Frith, 1952). Any group of plants are likely to compete with each other for limited resources. The key point here is whether any competitive disadvantage suffered by the tree is significant or not. It is important to remember that any such disadvantage will be offset by benefits from nutrient cycling, water conservation through
reduced evaporation, soil structural improvement and pest management. The issue of competition is one vexed by anecdote, folklore and prejudice, and would benefit from a detailed and objective up-to-date review of the available literature. However, this report is not the appropriate place for such a study, since neither time nor space permit. Another widelyheld belief is that permanent ground cover encourages weed growth and spread. In some orchards it does, in others it does not. We have noted anecdotally that more species-diverse swards tend to have fewer significant weeds. Slashing can be undertaken to preve nt build-up of weed seed-banks or other means used, such as ranging fowls (which also can add significant nutrients, cf. Bowman, 1956), or development of an integrated weed management strategy. In general, we could not detect clear trends in economic, environmental or ecological parameters that related to generic management practices, i.e. the general manner in which citrus was produced. Although the orchards were selected as paired replicates by management practice, each orchard was distinctly different from any other in its characteristics and the way it operated. For example, the organic properties varied considerably from each other in almost every parameter. But then one had been managed organically for about 12 years, with considerable active investment in building up the organic matter profile of the soil, whereas the other had been managed organically for only about 4 years, with less emphasis on management of soil organic matter content. We investigated the usefulness of input-output analyses of profitability, nutrients, energy and water as key indicators of sustainability. Although we collected and analysed data for only one year, and can only present a partial, comparative snapshot of the economic and environmental state of each enterprise, the fact that primary data already existed in the form of farm records indicates that on-going monitoring of these key indicators could be incorporated as part of the Environmental Management System for citrus production. There is considerable flexibility within citrus production systems towards achieving ecological and economic sustainability. Each enterprise will have its own set of priorities and means of achieving these. The value of the input-output analyses presented herein has been to provide a framework for growers to understand the key components of sustainability and how those components interact. Furthermore, these analyses have helped to diminish the human construct of divisions between economic, environmental, social and ecological parameters and demonstrate that they are all linked in some way or other. Parameters thought of as primarily environmental can, when looked at from a different viewpoint, be seen to be of economic significance - soil carbon content, for example. The concept of linked parameters and systems takes us towards ideas relating to understanding the characteristics of complex systems and how these systems develop and can be managed. The value of understanding the linkages within a production system lies mainly in its predictive power. Rather than having to rely on empirical observations, which can be costly and time-consuming to complete, one can make a prediction about how altering one parameter will affect the other parts of the system. This is an enormously powerful concept and one that has profound implications for the way we think about and manage our land. Yet this idea of the power of making predictions from a theoretical basis and understanding the system holistically all seems rather obvious. Surely farmers are already doing this! Well, yes and no. Some are, as applied to particular parts of particular production systems, but we are a long way from an intellectual framework that recognises and accepts that production systems operate as ecosystems, and are subject to exactly the same ecological and environmental rules and constraints as natural ecosystems. Another valuable lesson that has emerged from this study is that there can be no universal set of sustainable management practices. This is because not all farmers start from the same point, i.e. with the same set of economic and environmental resources. What is relevant to
farmers in one region or catchment can be a minor issue to those in another. For example, salinity is a major problem in Sunraysia, but is not yet a significant constraint in the Riverland. The selection of a particular set of management options will represent a careful, considered balance between benefits to the enterprise and to the broader environment, taking into account existing local economic and environmental priorities.
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Walker, B., Carpenter, S., Anderies, J., Abel, N., Cumming, G.S., Janssen, M., Lebel, L., Norberg, J., Peterson, G.D. and Pritchard, R. (2002) Resilience management in socialecological systems: a working hypothesis for a participatory approach. Conservation Ecology, 6, 14. [online] URL: http://www.consecol.org/vol6/iss1/art14 Walter, D.E. and Ikonen, E.K. (1989) Species, guilds and functional groups: taxonomy and behaviour in nematophagous arthropods. Journal of Nematology 21, 315-327. Walter, D.E. and Kaplan, D.T. (1990) A guild of thelytokous mites associated with citrus roots in Florida. Environmental Entomology, 19, 1338-1343. Walter, D.E. and Lindquist, E.E. (1995) The distributions of parthenogenetic ascid mites (Acari: Parasitiformes) do not support the biotic uncertainty hypothesis. Experimental and Applied Acarology 19, 423-442. Wardle, D.A., Giller, K.E. (1996). The quest for a contemporary ecological dimension to soil biology. Soil Biology and Biochemistry, 28, 1549-1554. Yeates G.W., Bongers T., De Goede R.G.M., Freckman D.W., Georgieva S.S. (1993) Feeding habits in soil nematode families and genera - an outline for soil ecologists. Journal of Nematology 25, 315-31.
270 447 30 110 270
12.4 3.1 5.5 36.8
0.3 34.3 102.9 36.3 5.5 15.5 3.6 1.5 1.62 10.2 13.8 10.4 4.3 46 0 158.6 P% 23.6 8.23 0.096 6.964 5.17 0.64 1.57 3.11 3.7 6.5 9
0 N% 33.5 15.5 13.8 46 7
C% 16 10 10 9 8.93 6
Carbon Ground-applied Alroc Blood/meat and bone Composted cow manure Composted duck manure Composted pig manure Rapid Raiser' poultry compost Total Nitrogen Foliar sprays Ammonium nitrate Calcium nitrate Potassium nitrate Urea Urea phosphate Ground-applied/fertigation Alroc Nitram (NH4NO3 + Mg(NO3)2 Blended fertiliser (N,P,K,Ca,S,Mg) Blood/meat and bone Calcium nitrate Composted cow manure Composted duck manure Composted pig manure NPK (10.4.4) Potassium nitrate Rapid Raiser' poultry compost Urea % organic N Total N Phosphorous Foliar sprays Phosphoric acid (ortho-) Urea phosphate Ground-applied/fertigation Alroc Blended fertiliser (N,P,K,Ca,S,Mg) Blood/meat and bone Composted cow manure Composted duck manure Composted pig manure NPK (10.4.4) Rapid Raiser' poultry compost Superphosphate % organic P Total
Appendix 1. Elemental Nutrient Content of Foliar Spray and Fertiliser Inputs (kg ha yr)
1.5 17.1 137.8 66
22 62 72
180 46 81
31 21.5 18.4 93.5 63.7 0 100 100 23 72.1 26.3 245.6 102.9
0 38.2 48.1 151 188.6 119
26.5 62 32
47.1 155.5 111 32.5 63 0 63.0
45.0 85.2 50.0 34.6 94.2
100 100 94 176.2
0 10.3 42.7 26.5 123.8 75.8
0.6 16.91 0.5 2.38 0.85 0.86 48 4.2 38.6 1.8
25.5 43.0 96.0 12.6 29 9 75 100 12.0 25.5
100 100 125 45.0
7.5 5.5 0.5 0.5
4.2 15.827 12.147 21 1.6 3.6 5.39 7 21
21 60.1 145.8 48.6 16.8 32
80 108 269.5 35 4.2
2.9 3.719 0.5 0.49 0.65 1.65 0.26 0.7
Na% 0.3 0.43 0.25 0.11 0.1
Foliar sprays Potassium nitrate Ground-applied/fertigation Alroc Blended fertiliser (N,P,K,Ca,S,Mg) Blood/meat and bone Composted cow manure Composted duck manure Composted pig manure Muriate of potash (KCl) NPK (10.4.4) Potassium nitrate Rapid Raiser' poultry compost % organic K Total Sodium Ground-applied Blood/meat and bone Composted cow manure Composted duck manure Composted pig manure Rapid Raiser' poultry compost Total Calcium Foliar sprays Calcium nitrate Ground-applied Alroc Blended fertiliser (N,P,K,Ca,S,Mg) Blood/meat and bone Calcium nitrate Composted cow manure Composted duck manure Composted pig manure Rapid Raiser' poultry compost Superphosphate Total Magnesium Foliar sprays Magnesium sulphate Ground-applied/fertigation Alroc Blended fertiliser (N,P,K,Ca,S,Mg) Blood/meat and bone Composted cow manure Composted duck manure Composted pig manure Nitram (NH4NO3 + Mg(NO3)2 Rapid Raiser' poultry compost Total
0 225.8 318.1
14.5 14.1 6.0 24.5
19.5 82.5 0.8 3.1 17.6 19.5
2.2 30.5 84.5
Foliar sprays Manganese sulphate Mantrac 500 Ground-applied Alroc Blood/meat and bone Composted cow manure Composted duck manure Composted pig manure Rapid Raiser' poultry compost Total Copper Foliar sprays Copper hydroxide Copper oxychloride Ground-applied Alroc Blood/meat and bone Composted cow manure Composted duck manure Composted pig manure Rapid Raiser' poultry compost Total Iron Foliar sprays Chelated iron Ground-applied Alroc Blood/meat and bone Composted cow manure Composted duck manure Composted pig manure Rapid Raiser' poultry compost Total Zinc Foliar sprays Zinc sulphate Zintrac 700 Ground-applied Alroc Blood/meat and bone Composted cow manure Composted duck manure Composted pig manure Rapid Raiser' poultry compost Total
Mn% 32 27.4 0.22 0.096 0.1 0.11 0.037 0.051 0.05
0.5 1.2 5.5
1.1 2.6 0.22
3.03 1.28 6.70
Cu% 35 57.1 2.28
2.86 1.71 1.14
0.0016 0.02 0.02 0.0038 0.023 0.0006
2.95 3.84 4.12 3.15
0.008 0.24 1
0.114 1.15 2.28
2.97 1.71 2.38
1.23 1.43 1.98 2.18
Fe% 10.5 0.15 2.5 0.5 0.19 0.26 0.557 0.2
0.95 12.5 6 9.5
7.8 27.85 0.15
Zn% 22 39.7 0.56 0.0064 0.04 0.09 0.028 0.099 0.04
3.74 1.32 1.76
0 4.75 8.19
1.76 3.52 1.98
0.03 0.48 4.5
0.84 4.95 0.56
4.58 1.32 6.74
6.87 3.52 4.18 3.58
3000 184514 80
20 1230 3100 190531 700
500 9 509
4812 87 4898
22 380 20 422
1316 23066 1230 25612
High-tech 1 MJ
kg Inorganic N fertiliser Nitram (ammonium nitrate) NPK (10:4:4) Urea + urea phos. Blended fertiliser Calcium nitrate Total Inorganic P fertiliser Superphosphate (single) Phosphoric acid (ortho-)1 Total Inorganic K fertiliser Muriate of potash Potassium nitrate Alroc Total Total fertiliser Foliar Nutrient Sprays (non N,P &K) Iron chelate/Lig-iron Magnesium sulphate Manganese sulphate Mantrac 500 (Manganese) Phosphoric acid (ortho-)1 Zinc sulphate Zintrac 700 (Zinc) Total
Appendix 2. Inputs (kg ha yr) Converted to Energy Input Values (MJ ha yr)
50 300 15
3075 7999 897
1029 300.0 45 380 40 1794
63288 7999 2707 23066 2460 29893
80 4920 445 16892
600 5774 9 87 609 1465
0 0 445 16892
200 1339 125 837 500 3347 825 690 3228 32048
125 837 3925 198104
500 3347 500 3347 509 3434
200 1339 264 5168
6 9 1.4 6
0 0 422 25612
9 9 6
315 315 210
5.2 11 7 0.8 9 11.2 1.4 46
182 385 257 28 315 392 49 619
Pesticides Amount MJ Amount MJ Amount MJ Amount MJ Amount MJ Amount MJ Amount MJ Amount MJ Amount MJ Nematicides & Insecticides Miscible oil Chlorpyriphos 1 (L) 1.7 619 1.7 619 Methidathion2 (L) 0.6 218 0.6 218 Summer oil (L) 108 39312 108 39312 Trichlorfon/chlorofos 1 (L) 1.23 448 1.23 448 Granules Aldicarb (kg)* 46 14306 46 14306 46 14306 Total 46 14306 0 0 109.23 39759.7 48.3 15143 0 0 0 0 0 0 0 0 158 8651 Herbicides Miscible oil Glyphosate 2 (L) 2 836 5 2090 2 836 2 836 2.8 1150 Wettable powder Bromacil1 (kg) 2 526 0.4 105 2 526 1.5 386 Diuron 1 (kg) 1.63 429 1 263 1.3 346 Simazine1 (g) 1 263 1 263 Total 3.63 1791 0 0 0 2090 2.4 1467 0 0 0 0 0 0 2 1362 3.8 839 Fungicides Copper oxychloride1 (kg) 4 864 4 864 5 1080 3 648 2 432 2.5 540 3.4 738 Copper hydroxide (kg) 4.5 972 4.5 972 Mefenoxam 1 (kg) 13 2808 13 2808 Total 4 864 4 864 18 3888 3 648 2 432 0 0 2.5 540 4.5 972 20.9 1026 Miscellaneous Wetting agent (L) 12.4 12.4 Cit-tite (L) 4 4 Giberellic acid (L) 1 1 Total 0 0 0 0 0 0 17.4 0 0 0 0 0 0 0 0 0 17.4 0 Pesticide + misc. Total 54 16961 4 864 127 45738 54 17258 2 432 0 0 2.5 540 6.5 2334 182.2 10516 Grand Total 3984 215261 522 4613 705 53821 350 23546 2 432 8 280 453 27132 485 20381 3456 43183 *application cost = $100/ha flat rate; kg/ha based on canopy width (m): 1m =14 kg/ha; 2=27; 2.5=36; 3=46; 3.5=54; 4=63; 4.5=72
Appendix 3. Production Energy Values of Different Inputs Input Energy MJ Electricity (AGL) per kilowatt hour Fuel (diesel per litre) Machinery Transport Fertilisers (per tonne) Inorganically-derived nitrogen fertiliser Nitram (ammonium nitrate) NPK (10:4:4) Urea Blended fertiliser Inorganically-derived phosphorous fertiliser Superphosphate (single) Inorganically-derived potassium fertiliser Muriate of potash Potassium nitrate Alroc Foliar Nutrient Sprays (non N,P,K) (based on mean of N,P,K production energy) Insecticides Miscible oil Chlorpyrifos (Lorsban) (L) Methidathion (L) Summer oil (L) Supricide (L) Trichlorofon Granules Temik (Aldicarb) Wettable powder
61.5 37.33 59.83 60.70 9.62 6.69 6.69 34.98
Herbicides Miscible oil
418 Glyphosate (L)
Granules Wettable powder
362 263 Diuron (kg) Bromacil (Hyvar) (kg) Simazine (kg)
216 Copper hydroxide (kg) Copper oxychloride (kg) Kocide (kg) Mefenoxam (kg) Phosphoric acid (ortho-) (kg)
Appendix 4. Costs of inputs ($). Figs. in bold = estimates based on ABARE index of prices 99/00 Electricity (AGL) per kilowatt hour Water - irrigation levy per megalitre Fuel (diesel per litre) Fertilisers (per tonne) Alroc Blended fertiliser Blood/meat and bone Calcium nitrate Composted cow manure Composted pig manure Composted duck manure Rapid Raiser' composted poultry manure Muriate of potash Nitram (ammonium nitrate) NPK (10:4:4) Potassium nitrate Superphosphate (single) Urea Foliar Nutrient Sprays Iron chelate/Lig iron Magnesium sulphate (t) Manganese sulphate (t) Mantrac 500 (L) Urea phosphate (L) Zinc sulphate (t) Zintrac 700 (L) Pesticides Temik (Aldicarb) application cost per ha* Chlorpyrifos (Lorsban) (L) Copper hydroxide (kg) Copper oxychloride (kg) Kocide (kg) Mefenoxam (kg) Methidathion (L) Phosphoric acid (kg) Summer oil (L) Supricide (L) Trichlorofon Herbicides Bromacil (kg) Diuron Glyphosate (L) Hyvar (kg) Simazine (g) Other Cit-tite (L) X77 (Agriwet) (L)
Mar 2002 0.12 65.00 0.75 253.55 550.00 461.00 774.48 35.00 65.00 31.00 380.00 527.38 398.30 1032.64 213.90 460.00
64.00 300.00 500.00 572.00 432.00 1120.00 232.00 458.60
731.12 630.00 12.12 3.60 600.00 12.12
760.00 920.00 12.60
105.82 12.75 3.00 3.08 10.77 7.00 13.00 3.00 2.84 23.00 11.00
13.80 13.08 5.77 42.00 8.40
15.50 13.60 6.00 56.00
*application cost = $110/ha flat rate
3.30 2.95 29.00
Appendix 5. Calculation of nutrient and energy content of crop and of organic fertiliser inputs. Output calculations based on 1 average fruit = 145 g, average fruit/tonne: 6290. Fertiliser analysis (% w/w wet weight)
P & K (cf. Wisconsin)
Cow manure average
3.94 1.38 3.28 1.97 0.79 ND 0.118 ND 0.04 0.157
4.6 0.28 1.34 0.23 0.1 0.06 0.005 0.009 0.04 0.005
10 3.60 0.64 2.38 1.60 0.49 0.43 0.11 0.02 0.19 0.09
Dairy Solid (Wisconsin)
10 5.47 2.27 ND ND 5.17 0.56 0.61 0.39 0.5 0.62 1.94 4.7 12.1 1.62 2.03 2.16 0.5 0.68 0.46 0.42 ND 0.07 0.69 0.91 0.1 0.163 0.117 0.161 0.02 0.027 0.024 0.021 0.5 0.13 0.22 0.51 0.04 0.09 0.115 0.086
Blood and bone average
Proprietary blood and bone 3
8.1 4.8 6 5 ND ND 12.2 15.24 ND ND ND ND ND ND ND ND ND ND ND ND
Composted Cow Manure Capar et al.2 (cf. Wisconsin)
29.3 12 15 58052 2.4 16 6 8.93 9 0.07 0.28 5 1.62 1 3.5 5.2 0.096 6.5 3.11 1.36 4.5 63.5 0.6 1.8 0.86 0.83 0.5 17.2 4.2 7 5.39 1.13 9 3.9 2.9 0.7 1.65 0.17 0.5 0.34 ND ND 0.11 0.27 ND 0.009 0.072 0.05 0.051 0.018 0.1 0.018 0.0016 0.0006 0.023 0.0025 0.02 0.117 2.5 0.2 0.557 0.053 0.5 0.027 0.0064 0.04 0.099 0.017 0.04
Proprietary blood and bone 2
Proprietary blood and bone 1
Composted duck manure
Composted pig manure
853 1690 70 1.9 150 1850 500 113 10 0.3 0.5 3.4 0.8
85.3 123.7 185.3 268.7 7 10.2 0.19 0.28 15 21.8 185 268.3 50 72.5 11.3 16.4 1 1.5 0.026 0.0377 0.053 0.07685 0.34 0.493 0.08 0.116
amount per hectare
amount per tonne
mL,mL,L,kL kj,kj, mj, mj g,g,kg,t g,g,kg,t mg,mg,g,kg " " " " " " " "
amount per fruit
Water Energy Carbon Nitrogen Phosphorus Potassium Calcium Magnesium Sodium Manganese Copper Iron Zinc
amount per 100 g
units (per fruit/tonne/ha)
Blood and Bone
Capar et al.1 (cf. Wisconsin)
Citrus fruit analysis (wet wt.)
Appendix 6. Methods of Preparation of Soil Samples Prior to Analysis (Analytical Methods Developed and Used by Department of Forestry, Australian National University 1. Determination of Exchangeable-Extractable Cations in Soil (K, Mn, Ca, Mg, Na) but not Zn. Sample Preparation Soil samples are collected, air-dried, rolled and sieved through a 2mm sieve. Sub samples (10g approx) are placed in sealable glass vials and oven dried at 105-C for 8 hours or overnight. While warm, the vials are sealed to prevent water uptake from the air. Procedure • 5g (weighed to 4 decimal places) of soil are placed in 35-40 ml plastic vials with flip-top lid. Each sample is extracted 3 times with 1 molar ammonium acetate (A.R.) pl-17. (77.08g/litre). TO ADJUST THE pH OF AMMONIUM ACETATE USE EITHER DILUTE NH4 OH (will increase pH) or ACETIC ACID (will decrease -pH). 5 litres of IM AAC will be sufficient for 38 samples plus 2 blanks. • For each extraction, 25ml of IM AAC pl-17 is added to the sample. Vials are shaken on rotary shaker for 1 hour then centrifuged (1000 rpm). • The supernatant is decanted and filtered (Whitman No. 42) into 100 ml Pyrex volumetric flasks. • Filter papers are rinsed with IM AAC and made up to 10Orni with IM AAC • If not analysing for K, IM KCL (74.56g/litre) can be used. Samples in 10O ml volumetrics MUST be diluted at least once before analysing to match sample and standard viscosity and AAC concentrations. • Samples analysed on atomic absorption spectrophotometer • For Mn analysis, use HCI standards. If analysing for Na, do this element First. 2. Determination of Total Cations in Soil (Ca, Mg, K, Na, Mn, Fe, Cr, Cd, Zn, Pb, Cu, etc.) using Wet Digestion Method Sample Preparation Same as for (exchangeable) extractable cations in soil. Procedure • Weigh O.5g (to 4 decimal places of sample into 100 or 125ml wide mouth Pyrex conical flasks. • Add 15ml nitric acid first, then add 5ml of perchloric acid. N.B. PERCHLORIC ACID IS EXTREMEMLY DANGEROUS AND MUST NOT BE USED ALONE FOR THE DIGESTION OF SAMPLES (it is explosive). • Simmer on a hot plate in a fume hood with scrubbing facilities. Simmer until volume decreases to 1-2 ml. Do not allow sample to dry out. If this happens, the sample should be remade. • Using distilled water, wash contents of flasks through filter paper (Whatman No. 42) into 100 ml volumetric flasks. Rinse several times and make up to mark. • Samples analysed on atomic absorption spectrophotometer
Appendix 7. Key to some soil- inhabiting Mesostigmata from citrus orchards in the Riverland of South Australia. R. B. Halliday, February 2000 1.
Body completely soft, without visible plates or ornamented areas of skin; with 6 or 8 legs ...................................................................................................immatures Body with at least 1 visible plate or area of ornamentation; with 8 legs ............ 2
Ventral surface with a large elongate triangular plate extending from between front legs to between hind legs (Fig. 1) ...........................................................immatures
Fig. 1 Unidentified deutonymph Ventral surface without this elongate triangular plate; either with a single large plate covering most of ventral surface (Fig. 2),
Fig. 2 Zygoseius sarcinulus or with several smaller plates (Figs. 3,4) (adults)............................................... 3
Fig. 3 Zygoseius sarcinulus 3.
Fig. 4 Athiasella relata
With genitalia visible at anterior margin of sternal shield (Fig. 5) ............. males
Fig. 5 Athiasella relata Without genitalia at anterior margin of sternal shield……………….females, 4 4.
Dorsal shield completely divided into two by a transverse suture (Fig. 6) ........ 5
Fig. 6 Dendrolaelaps sp. Dorsal shield undivided (Figs. 7,8,9,10)........................................................... 12
Fig. 7 Hypoaspis sp.
Fig. 8 Arctoseius cetratus
Fig. 9 Athiasella relata 5.
Dorsal shields with strongly developed conspicuous ornamentation of tubercles or polygons (Figs. 11,12,13) .............................................................................. 6
Fig. 11 Antennoseius sp. B
Fig. 12 Antennoseius sp. A.
Fig. 13 Antennoseius sp. B
Dorsal shields smooth, without conspicuous ornamentation (Figs. 6, 10) ......... 7 6.
Posterior margin of posterior dorsal shield with a pair of prominent horns, each bearing a pair of large setae (Fig. 14) ............................................ Asca sp. (Ascidae).
Fig. 14 Asca sp. (Ascidae). Posterior margin of posterior dorsal shield without prominent horns or large setae (Fig. 8, 10) ............................................................................................................ 18 7.
Leg I without claws (Fig. 15); anterior dorsal shield with a V-shaped (not straight) transverse groove in its anterior third (Fig. 16) ..........….. Rhodacarus roseus (Rhodacaridae)
Fig. 15 Fig. 16 Rhodacarus roseus (leg I) Rhodacarus roseus Leg I with claw (Fig. 17); anterior dorsal shield without a V-shaped transverse groove ..........................................................................................................................
Anterior dorsal shield with 4 distinct nodules near its posterior margin (Fig. 18)….9 Anterior dorsal shield without these nodules (Fig. 19)..................................... 10
Fig. 18 Dendrolaelaps sp.
Fig. 19 Protogamasellus massula
First pair of sternal setae inserted in sternal shield (Fig. 20) ................................ .....................................................................Dendrolaelaps sp. (Digamasellidae)
Fig. 20 Dendrolaelaps sp. (Digamasellidae) First pair of sternal setae inserted in soft granular skin (Fig. 21) ......................... ......................................................... Rhodacarellus silesiacus (Rhodacaridae)
Fig. 21 Rhodacarellus silesiacus (Rhodacaridae) 10.
Ventral surface with conspicuous forward-directed V-shaped genital flap (Fig. 22) ................................................................................ Pergamasus sp. (Parasitidae)
Fig. 22 Pergamasus sp. (Parasitidae) 85
Ventral surface without this V-shaped genital flap .......................................... 11 11.
Anterior dorsal shield with a straight transverse groove across the anterior third (Fig. 23) .................................................................... Protogamasellus mica (Ascidae)
Fig. 23 Protogamasellus mica (Ascidae) Anterior dorsal shield without a transverse groove (Fig. 24) ............................... .................................................................Protogamasellus massula (Ascidae)
Fig. 24 Protogamasellus massula (Ascidae) 12.
Anus in an anal shield with 3 setae around the anus plus 1 additional pair of setae (Fig. 25); separate ventral shield present between genital shield and anal shield (Fig. 26) .... .......................................................................................... Veigaia pusilla (Veigaiidae)
Fig. 25 Veigaia pusilla (Veigaiidae)
Anus at the posterior edge of a large ventri-anal shield which bears 3 setae around the anus plus at least 3 other pairs of setae (Figs. 27, 28) ...........................................13
Fig. 27 Zygoseius sarcinulus
Fig. 28 Athiasella relata
Anus near the centre of a small or medium-sized anal shield which bears only 3 setae around the anus (Figs. 29, 30)................................................................................14
Fig. 29 Hypoaspis sp. B 13.
Fig. 30 Arctoseius cetratus
Pre-sternal plates present (Fig. 31); posterior dorsal shield setae long (Fig. 32) . ......................................................................... Athiasella relata (Ologamasidae)
Fig. 31 Athiasella relata (Ologamasidae)
Pre-sternal plates absent (Fig. 33); posterior dorsal shield setae very short (Fig. 34) ............................................................... Zygoseius sarcinulus (Pachylaelapidae)
Fig. 33 Fig. 34 Zygoseius sarcinulus (Pachylaelapidae) 14.
Ventral plates heavily ornamented in a pattern of ridges; ventral surface with wide conspicuous plates outside the legs, extending behind the hind legs in a triangular projection (Fig. 35) .......................................Pachylaelaps sp. (Pachylaelapidae)
Fig. 35 Pachylaelaps sp. (Pachylaelapidae) Ventral plates with little or no ornamentation; ventral surface without a conspicuous plate outside the legs and projecting behind the hind legs ........................... 15
Dorsal shield setae expanded, feather-shaped (Fig. 36)……Hypoaspis sp. A (Laelapidae)
Fig. 36 Hypoaspis sp. A (Laelapidae) Dorsal shield setae smooth, pointed, needle- like (Fig. 37)............................... 16 16.
Hind legs with at least 5 long heavy spine-like setae (Fig. 38) ............................ ........................................................................... Hypoaspis sp. B (Laelapidae)
Fig. 37 Hypoaspis sp. B (Laelapidae)
Hind legs with only fine needle- like setae (Fig. 39)......................................... 17
Fig. 39 Arctoseius cetratus (leg iv)
Anal shield wider than long (Fig. 30); posterior tip of body with two conspicuous setae much longer than the rest (Fig. 30)................... Arctoseius cetratus (Ascidae)
Anal shield longer than wide (Fig. 40); posterior tip of body with setae all of uniform length (Fig. 41).......................................................Arctoseius sp. A (Ascidae)
Fig. 40 Arctoseius sp. A (Ascidae) 18.
Anterior pair of dorsal shield setae short, pointed (Fig. 42) ................................. ............................................................................... Antennoseius sp. A (Ascidae)
Fig. 42 Antennoseius sp. A (Ascidae) Anterior pair of dorsal shield setae expanded, bushy (Fig. 43) ............................ ........................................................................... Antennoseius sp. B (Ascidae)
Fig. 43 Antennoseius sp. B (Ascidae)
Appendix 8. Natural Heritage Trust Citrus Sustainability Group Project Manual and Audit Sheet March 2002, Draft No. 1 Information contained in this document is the property of the NHT Citrus Sustainability Group (currently incorporated as the Movement for Ecologically Sustainable Horticulture). Contents Disclaimer Acronyms Acknowledgments Introduction Manual Grower's Background Information 1. Soils 2. Irrigation 3. Drainage and Salinity Management 4. Nutrition 5. Sustainable Crop Protection 6. Ground Cover Plant Management 7. Social and Environment References and Recommended Reading Peer-audited Certification Process Audit Sheets Disclaimer The information contained in this document is presented in good faith and we hope it is of assistance to the reader, but the Citrus Sustainability Group does not make any guarantee that this publication is without flaw or appropriate to the reader's use and therefore does not accept any liabilities for inaccuracies, or for any loss or damage resulting from the use and/or reliance upon the information or advice contained in this Manual and the accompanying Audit Sheet. Reference and adherence to legislation and regulations noted in this Manual and Audit Sheet are entirely the responsibility of the reader, and the Citrus Sustainability Group does not accept any liability for interpretations of this work made by any reader or user. The nature of the peer-audited certification process detailed in this Manual and Audit Sheet means that each audit undertaken to certify a grower by this process will be subject to a degree of interpretation by the auditors. In the preparation of this Manual and Audit Sheet, and in overseeing the certification process, the Citrus Sustainability Group and individual auditors participating in this process have and will endeavour to be fair and credible. However, neither the Citrus Sustainability Group nor individual auditors accept liability or responsibility for this interpretation or for the ensuing results of any particular audit. No parts of this publication may be reproduced, stored or transmitted in any form or by any means without prior permission from the Citrus Sustainability Group Acknowledgments Citrus Sustainability Group Members and Working Teams 1. 2. 3. 4. 5. 6. 7.
Soils: Grant Brown, Trevor Ziersch Irrigation: Matt Goodwin, Mick Punturiero Drainage and Salinity Management: Matt Goodwin, Mick Punturiero Nutrition: Ian Armstrong, Shane Phillips Sustainable Crop Protection: James Altmann, David Ingerson, Darryl Lang, Julie Sippo Ground Cover Plant Management: David Ingerson, Ian King Social and Environment: Humphrey Howie, Darryl Lang, James Altmann, Steve Gibbs
Editor Tamara Boland Professional Support Dr Matthew Colloff, CSIRO; Australian Landscape Trust; Patricia Feilman; Dr Pamela Parker; Tamara Boland; Deborah Bogenhuber; Jelena Mastilovic; SARDI; PIRSA; Department of Natural Resources and Environment, Victoria; Waite Institute; Citrus Board of South Australia; Citrus Industry Development Officers; Biological Services; Yandilla Park; Chris Barry Properties; Belair Orchards; Elders - RHT Administrative Support Australian Landscape Trust Acronyms AQIS CITT groups EC EPA GMO HACCP IDMP IDU IPM LBAM MRLs NASAA NRA OH&S OHS&W Legislation PMP RAW SQF QA System
Australian Quarantine Inspection Service Citrus Information Technology Transfer groups electrica l conductivity Environment Protection Authority genetically modified organism Hazard Analysis Critical Control Point Irrigation and Drainage Management Plan irrigation distribution uniformity Integrated Pest Management Light Brown Apple Moth Maximum Residue Limits National Association for Sustainable Agriculture Australia National Registration Authority Occupational Health and Safety Occupational Health, Safety and Welfare Legislation Property Management Plan readily available water Safe Quality Food Quality Assurance System
Introduction During the 1990s a group of Riverland citrus growers, all from diverse backgrounds in production methods and expertise, united in a holistic approach to management and the pursuit of sustainable citrus production. The group recognised the need to develop ecologically sustainable production in order to secure a viable, long-term future for the Riverland citrus industry. A Natural Heritage Trust grant was received in 1997 to address two areas. Firstly, Dr Matthew Colloff, CSIRO, undertook a research project entitled “Soil Biodiversity and Ecosystem Function in Citrus Orchards in the Riverland of South Australia”. Secondly, the citrus growers provided in-kind support to this research project and agreed to oversee: • •
development of a code of best practice for growing citrus, and definition and certification of sustainable production in citrus.
Growers viewed sustainability in the terms described in the table below. Principles of Sustainability Minimal polluting effects on groundwater, surface water, atmosphere and soil;
Measures of Unsustainability Farming methods that result in: •
Soil fertility and soil ecosystem functions preserved and enhanced; Erosion and loss of soil nutrients are reduced; Water is used efficiently and not in ways that compromise needs of natural ecosystems or local
cumulative environmental degradation (erosion, loss of organic matter, loss of nutrients, loss of habitat and biodiversity and reduction of ecosystem services); reduction of ecosystem processes; disruption of ecosystem functions
Unsustainable agricultural production systems
communities; Resources are drawn from within agro-ecosystems; Soil biodiversity is managed to enhance mineralisation and pest control;
consume the principal as well as the interest of the natural capital and are characterised by declining productivity and loss of resilience Unsustainable farming is generally not holistic in its approach to using and conserving essential resources for production
The knowledge base of the local community is developed and enlarged in areas of production, marketing and other economic drivers; Investment is made to achieve a resilient and sustainable economy; Principles of ecology are used to guide farm production and provide whole-of-system dimension; Economic sustainability is incorporated as an integral part of ecological sustainability; Total resource inputs are accounted for on a local, regional, national and global scale; Sustainable agricultural production lives off interest of the natural capital and not the principal.
Riverland citrus growers involved in the NHT funded project chose soil biodiversity as a key to assessing and measuring the long-term effects of their production activities on the environment. Growers viewed soil health as a natural resource, which passes from generation to generation. The NHT grant allowed growers to gain fundamental knowledge of soil health, which could be used as an indicator of sustainability. Eight growers volunteered their properties for soil samples and subsequent analysis by Dr Matthew Colloff. This work commenced in August 1998. The research analysed soil biodiversity and nutrients in four management systems used by the growers. The data provided a scientific basis for developing a code of best practice standards of production. In broad terms the research showed that the properties with high plant biodiversity also had high soil biodiversity and lower incidences of insect pest damage. Results indicate that dense, diverse ground cover provides habitat and food resources for predatory insects which therefore maintain populations sufficient to control pest insect outbreaks. In addition to CSIRO, the growers were supported by others in the scientific community including SARDI, PIRSA, Victoria Agriculture, Waite Institute, Citrus Board of SA and Citrus Industry Development Officers who helped to find answers to growers’ questions about achieving sustainable citrus production. The Australian Landscape Trust, Biological Services, Yandilla Park, and Elders-RHT also contributed to the project. Code of Best Practice, Certification of Best Practice The code of best practice to achieve long-term sustainability is underpinned by science using biodiversity as an indicator of sustainability. To be credible, claims of sustainability need to rest on hard data. Growers chose to serve on working teams based on their individual areas of interest and expertise to define standards for these elements of citrus production. There was an investigation team of growers for each of these subjects: • • • • • • •
Soil Management Irrigation Management Drainage and Salinity Management Nutrition Sustainable Crop Protection Ground Cover Plant Management Social, Environmental Issues and Synergies.
The standards chosen by the growers in each of these subject areas reflect the philosophy behind best practice for each production element identified by the growers. The standards also define methodology of best practice
production and provide an auditing process for production activities. The growers translated best practice theory outlined in the code into measurable on-ground management actions. Growers have devised an audit protocol, which is designed to be reliable, transparent, fair, and credible so that all growers in the industry have the opportunity to participate and be certified. The certification process is designed to evolve with increasing capabilities of growers, rising standards of production, deepening awareness by consumers of environmental aspects of sustainability, and expanding knowledge of sustainable environmental management and importance of the ‘free goods and services’ available from biodiversity in agricultural production systems. Ongoing work for the project includes negotiating with an appropriate authority for the endorsement of the certification process developed by the growers and developing a logo that conveys the values of this program and is meaningful both within Australia and internationally. The vision for this certification program is to incorporate best management practices with consumer education to form a partnership in the market place to achieve environmental equity in citrus production. This publication, in a form readily accessible to growers, of the results of the research underpinning the growers’ approach to environmental sustainability and the certification program completes the first stage of this process. Larger scope of the project This certification program is equally applicable to all horticultural production and perhaps to all agricultural production as well. The growers’ goal is to invest in the development process for this certification program so that primary producers in other industries who share common values for sustainability can readily adopt it.
Manual of Sustainable Citrus Production Grower's Background Information Owner's Name Owner's Address Telephone Number Email Property Name Road Address Section Numbers Years of Ownership Management Practices (eg certified organic, conventional, insecticide free, etc.) Certifications (eg SQF, NASAA, Chemical Handlers Certification, etc.) Varieties Rootstock
Irrigation system by plot
Years of Experience
Explanation of personal philosophical approach to citriculture Explanation of personal philosophical approach to sustainability Essential Prerequisites Growers must have achieved competency in documentation of orchard activities, including a Quality Assurance System, must have been accredited with a Chemical Users Certificate, and must be competent in the keeping of a comprehensive Spray Diary. 1. Soils Philosophy Sustainable soil management at a farm enterprise level is about maintaining the diversity and complexity of natural systems. The aim is to maintain the productive potential of the soil. Sustainable production methods are often individualistic and site specific. This is not an attempt to standardise the approach to soil management. Sustainability requires conservation of non-renewable resources like the soil. Long-term improvement is to be encouraged. Practice and Standards 1.1 Records Required 1.1.1 Growers must have a map or recent aerial photographs of the property.
Encouraged 1.1.2 Growers should aim to incorporate maps and property details into farm management software (eg, ‘Hortfarm’ or similar). 1.2 Data Required 1.2.1 Growers must have soil maps and /or topographic (contour) maps of the entire property. Encouraged 1.2.2 Growers are encouraged to undertake and document soil surveys to determine physical properties including soil structure/type, depth to restrictive or impenetrable layers, texture and pH (eg, Irrigation and Drainage Management Plan). 1.2.3 Growers are encouraged to maintain a map showing where the soil samples were taken and the soil properties of each site, including root zone depth and readily available water (RAW*). *RAW is the readily available water (that the trees' root system can easily absorb). It is dependent on the soil characteristics of each orchard. 1.3 Monitoring Encouraged 1.3.1 Growers should be able to demonstrate awareness of the methods and services available to measure soil nutrient and biological status. 1.3.2 Growers should aim to undertake monitoring to demonstrate that the soil resource is not degrading and, hopefully, is improving. 1.3.3 Growers are encouraged to regularly observe and document plant health and changes to plant diversity and biodiversity. 1.3.4 Growers should attempt to undertake chemical soil analysis for nutrients pH and salinity EC. 1.4 Nutrient Inter-relation Required 1.4.1 Growers must have a demonstrated understanding of how soil pH influences availability of nutrients and by what management practices this is influenced. (For example, Iron Chlorosis caused by saturated carbonate layers during spring when soil temperatures are low.) Encouraged 1.4.2 Growers should aim to observe, document and correct nutritional problems, eg, fertiliser application records and/or records of irrigation practices. 1.4.3 Growers are encouraged to seek specialist advice on problem areas. 1.5 Soil Management Required 1.5.1 Growers must implement management practices that maintain or increase the organic carbon levels in the soil. Encouraged 1.5.2 Planting of cover crops and mulching to improve nutrients and friability of the soil is encouraged. 1.5.3 Growers should attempt to measure organic carbon levels in the soil and its change over time as demonstrated by analysis. 1.6 Degraded Area Management Required 1.6.1 Identification and mapping is required of areas degraded by compaction, water run-off, erosion by wind or water, and salinity. Encouraged 1.6.2 Identification and amelioration of soil compaction, by adding organic matter/composts, gypsum or deep ripping where appropriate is encouraged. 1.6.3 Growers should attempt to minimise tillage and compaction to conserve soil structure, i.e., don’t drive on or cultivate soils that are too wet, or use lighter vehicles where possible, or reduce the number of machinery passes for a particular operation.
1.7 Alternative Planting Required 1.7.1 Growers must demonstrate an understanding of the need to select the appropriate crop and rootstock for a soil type. Encouraged 1.7.2 Growers should attempt to use soil survey data to select areas suitable for various crops/rootstocks. 1.7.3 Growers should seek help from advisers or plant nurseries. 1.8 Pest and Disease Awareness Required 1.8.1 Growers must demonstrate awareness of the risks of importing soil pests and dis eases in planting material, manures and organic matter/composts or soils. 1.8.2 Growers should have implemented a policy of only buying accredited products from approved suppliers. Encouraged 1.8.3 Receipt of chemical and disease status reports from approved suppliers of materials being imported is encouraged. 1.9 Importation of Pests Required 1.9.1 Growers must demonstrate an awareness of the possibility of pests and diseases and unwanted plant species being carried onto the property by people and vehicles. Encouraged 1.9.2 Growers should erect signs or verbally indicate to warn visitors that, due to pest and disease control, access to the property is restricted. 1.9.3 Where practical, restrict entry with fences and use wash bays and footbaths or foot covers. 1.10 Soil Populations Required 1.10.1 Growers must demonstrate an understanding of the role that soil biota and ecosystems play in the health of the soil. Encouraged 1.10.2 Growers should develop an understanding of conditions favourable/unfavourable to good soil biological health including: • soil aeration, • chemicals that influence soil micro and macro biota (for example, the build up of soil copper levels, the adverse or positive effects of some herbicides on soil pathogens), • the spread of soil diseases by surface water run-off (for example, Phytophthora zoospores), • plants with disease or mechanical damage which need removal. 1.10.3 Growers should obtain information on the management of soil biodiversity and ecosystems eg Colloff et al., 2002). 1.10.4 Observation by the grower or specialist of micro biological content (bacteria, fungi, algae, actinomycetes) and macro biological content (worms, insects, nematodes) of soil is encouraged. 1.10.5 Growers should aim to develop a management plan to maintain and improve soil biodiversity and ecosystem function.
2. Irrigation Philosophy "Irrigation has caused severe degradation of the River Murray floodplain, in particular through the disposal of drainage waters. In addition irrigation has caused local mounding of the highly saline ground waters which occur naturally along the Murray in South Australia and upstream. This mounding is driving increased salt loads to the Murray, causing salinisation of our water supply and reducing crop production levels. The drainage produced by over irrigating in South Australia currently adds more than 800 tonnes of salt per day to the river system and a further 300 tonnes per day is on its way. This degrades water quality and reduces the productivity of irrigated horticulture. It also increases everyone’s cost of using River Murray water in South Australia. Initiatives like the RiverCare Irrigation Management Course have been developed to reduce the present and future salt load impacts on the River Murray by improving on farm irrigation practices. RiverCare aims through improved irrigation management to: § maintain the quality of the River Murray § improve the environment § use water efficiently § increase our crop yields § raise our pride in our work as professional irrigators." (Quoted from the preface [ix] and introduction [p 2] of the The RiverCare Irrigators Manual) Practice and Standards 2.1 Records Required 2.1.1 Growers must have soil maps (including soil sample sites) and/or topographic (contour) maps of the entire property. 2.1.2 Growers must have recent aerial photographs and, if possible, data should be incorporated into ‘Hortfarm®’, or similar farm management software. 2.1.3 Drainage hazard areas must be clearly defined and managed/irrigated separately. Encouraged 2.1.4 An Irrigation and Drainage Management Plan (IDMP) should be presented as a detailed document that contains information related to the irrigated area of the property. The IDMP should contain: Soil plan, Vegetation plan, Crop layout, Irrigation system, Drainage system and Management practices. (For more detailed information refer to the website at www.agric.nsw.gov.au ‘Preparing an irrigation and drainage management plan’) 2.1.5 Growers are encouraged to undertake soil surveys (soil type, textures, layers and depths; calculation of soil RAW (readily available water)). 2.1.6 Identification and amelioration of soil compaction (link to soil management) is encouraged. 2.2 Information Education Required 2.2.1 Growers must have completed a ‘RiverCare Irrigation Management Course’ or similar irrigation training course(s). 2.2.2 If applicable to management practices, growers must have completed an additional ‘Drip Irrigation Course’ offered by ‘RiverCare’. 2.3 Monitoring Required 2.3.1 Growers must maintain documented evidence of calculation of soil RAWs (readily available water), and potential root-zone depths from soil survey data. 2.3.2 Planned /allocated irrigation units based on soil types, variety and age of trees are required. 2.3.3 Rates of water application for each irrigation unit and hours required to apply RAW value to the soil must be determined and documented. 2.3.4 Growers must be able to demonstrate irrigation application rates that are equal to or less than soil infiltration rates.
Encouraged 2.3.5 Consideration of crop water use factors, variety and age of trees is encouraged. 2.3.6 Consideration of rainfall, evaporation, wind, temperatures (heating/chilling units) and crop stage in determining irrigation schedules is encouraged. 2.3.7 Growers should aim to minimise the irrigation area wetted during the establishment of young trees and other desirable species to avoid watering soil outside of the root zone. 2.3.8 Growers are encouraged to measure water infiltration rates, address run-off problems, and implement soil treatments to improve soil water holding capacity and porosity/aeration (gypsum, organic matter/composts, brown coal, humic acids, polyacrylamides, link to soil management). 2.4 Irrigation Systems Required 2.4.1 Growers must be able to provide a pump performance curve and demonstrate that they have endeavoured to keep the flows for each irrigation shift as close as practicable to the more efficient region of the curve. (Greater than 65% pump performance efficiency for the majority of irrigation shifts would be a benchmark that could be used as a guide initially.) Note that water quality (suspended solids, etc) can also affect pump performance and the standard curves have been generated using clean water. 2.4.2 Growers must have in place an adequately designed and installed irrigation system that complies with the industry standard of greater than 85% efficiency*. Compliance with this benchmark can be determined by carrying out a complete system appraisal: start with the pump and work through to the sprinklers. This exercise would have been completed by growers who have attended a RiverCare course. (Refer to The RiverCare Irrigators Manual, pp 63-122) 2.4.3 A map of the irrigation system must be available. Encouraged 2.4.4 Calculating the number of kW/hrs (cost) required to pump each kL of water is a useful indicator of pump performance, suitability of mainline, sub-main sizes, and uncovering design flaws/faults in an irrigation system where large frictional and/or pressure losses are occurring. (Note link to Section 7 - energy budgets.) 2.4.5 Regular irrigation systems tests (IDU - irrigation distribution uniformity) should be carried out. The IDU system should be greater than 75%. 2.4.6 Regular monitoring of irrigation system: pump maintenance, cleaning filters, pressure testing, checking for leaks, flushing lines/valves is encouraged. *Note that older systems as well as newer systems that have been designed to a strict cost budget are unlikely to comply with this standard. 2.5 On-farm Monitoring Required 2.5.1 Growers must undertake field assessments of soil moisture content, drainage and crop response in each irrigation unit using digging/auguring, test wells and regular examination of trees for water stress during the morning (as hot, windy afternoons can cause symptoms of stress in trees regardless of soil moisture). Encouraged 2.5.2 Growers are strongly encouraged to use soil water monitoring equipment - Enviroscan®, Diviner 2000®, Tensiometers, Gopher®, Neutron probe, gypsum blocks, or similar devices in each major irrigation unit to determine the irrigation schedule. 2.6 Applications Required 2.6.1 Planned irrigation applications based on soil moisture, tree and crop requirements (physiological stage of growth), weather forecasts, water availability and total number of shifts in the orchard are essential. Encouraged 2.6.2 Growers should attempt to use all available weather forecasting information (eg, Bureau of Meteorology SILO 7-day outlook ‘meteogram’, ‘Farmweather Fax’, Pay TV Weather channel) in irrigation planning. It is also useful to be aware of the EC of river water at the time of irrigation (see www.riverland.net.au, click on SA Water link and follow the menus through to get daily EC values at various points along the river. The Murray Pioneer also publishes some of these values and they are reported on Win Television News).
2.6.3 Growers are encouraged to use dew points and weather information to determine frost management practices. If the dew point exceeds 5.5°C in the evening then the probability of frost is low. If the dew point is below 2.2°C in the evening and wind conditions are calm and skies are clear then the probability of frost is high. 2.6.4 Regular monitoring of soil pH and EC in all irrigated orchards is encouraged. The chloride and sodium levels in leaf nutrient analyses should also be used to assess the suitability of the irrigation scheduling, in particular, the leaching requirement. (The additional fraction (normally 5-10%) of the irrigation devoted to leaching excess salts and frequency with which the irrigation is applied.) 2.7 Data Required 2.7.1 All available information, such as water consumption records, meter readings, irrigation times and duration and water availability, must be recorded in an irrigation diary. (Refer to The RiverCare Irrigators Manual ‘record book’ as an example of what data to include in the diary.) 2.8 Orchard Management Required 2.8.1 Growers are required to undertake planned, regular skirting of trees in orchards with under tree sprinklers, so the skirts do not interfere with water distribution. (Refer to the Citrus Growing Manual: a manual for quality decision-making, Cultural Practices section, pp 13-17.) 2.8.2 Regular canopy pruning of trees in orchards with overhead irrigation is essential to keep the tops of the trees below sprinkler height, improve canopy penetration of watering and avoid excessive canopy run-off in varieties such as grapefruit and Kara mandarins. 2.8.3 Growers must not irrigate with overhead sprinklers during hot, windy weather so as to avoid poor irrigation efficiency due to high evaporation, non-uniform distribution and salt burn. 2.8.4 Growers must aim to irrigate during the evening or at night to minimise evaporation. Encouraged 2.8.5 Observation of shoot growth rates and weekly recording of fruit size measurements to compare with data from previous seasons will assist with irrigation planning. This will also enable growers to keep on track to reach a profitable target fruit size by harvest. 2.8.6 Growers should aim to use sap flow meters, leaf temperature probes, stomatal conductance meters and leaf porometers. This will assist growers in correlating soil moisture status and weather conditions to actual transpiration rates (sap flow) and measuring any water stress being experienced by the tree. (Access to this specialist equipment is currently through research bodies and consultants only and growers may need to approach researchers/consultants to gain access to this type of equipment or participate in field trials where it is used.) 3. Drainage and Salinity Management Philosophy Refer to Section 2 - Irrigation. Practice and Standards 3.1 Plans Required 3.1.1 Growers must have in place a properly designed and installed network of drains, where required. The distance between adjacent drains should be determined using soil texture, slope of orchard and other soil properties. (For a guide to determining effective drain spacing and depth, refer to Drainage for Sports Turf and Horticulture.) Encouraged 3.1.2 Growers should aim to retain and/or establish deep-rooted, salt tolerant vegetation positioned across the orchard where it will intercept sub-surface drainage water (eg, salt tolerant tree species like Eucalyptus occidentalis, other indigenous or native remnant vegetation, Lucerne, etc). 3.1.3 If applicable, pumping saline drainage water onto woodlots, Lucerne fields, re-use (untreated or diluted) on crops with higher salt tolerance, use in aquaculture ponds, etc is encouraged.
Important note: re-use of drainage water on food crops would have to comply with Food Safety regulations and be covered by a HACCP plan specific to the crop and its end use(s). 3.2 Monitoring Required 3.2.1 Growers must monitor test wells, record readings, and link changes in water table depth to irrigation applications and rainfall events and consider any changes when scheduling subsequent irrigations. Encouraged 3.2.2 Growers should aim to determine leaching requirements using soil salinity measurement and/or leaf tissue analysis, considering the lower limit of the root zone (determined by soil layers and textures, physical and/or chemical limitations in the soil profile, rootstock) and the sub-surface wetting pattern of the sprinkler/dripper. Monitoring the EC of drainage water (in drains) after irrigation is also a useful determinant of whether adequate or excessive leaching is occurring. 3.2.3 Occasional monitoring of drainage water for nitrates, phosphates and herbicides/pesticides is encouraged. (This type of analysis should become more commercially available in time as growers adopt their own Environmental Management Systems and EPA increases scrutiny of individual grower impacts.) 3.2.4 Growers are encouraged to carry out treatments and adopt practices aimed at increasing soil organic matter content, mounding (in a replant situation), and surface mulching which will assist with the management of higher than desirable soil and water EC levels. 4. Nutrition Philosophy It is essential that growers retain nutrients on-farm as much as possible and avoid the leaching of nutrients through the soil profile (refer to Section 1 - Soils). Nutrient management on properties should aim to maximise plant health and nutrient uptake by plants and to minimise erosion of the nutrient resource base in the soil. Growers are strongly encouraged to form a nutrient management plan for their property. The intention is to provide sufficient detail to allow an evaluation of implementation of the philosophy, in particular the extent to which nutrient/fertiliser applications are likely to remain within the root zone. The nutrient management plan should incorporate the following components that are already part of the assessment process elsewhere: • details of soil types and profiles (see Section 1- Soils; Section 2.1 - Irrigation) • water applications for each soil type (see Section 2 - Irrigation) • soil RAW (see Section 2 - Irrigation). During the audit process, no additional points should be awarded for these, since points have already been allocated under separate headings. Practice and Standards 4.1 Nutrient Management Plan and Implementation Required 4.1.1 Growers’ records (diary, nutrient management plan) must contain details of: • types of fertilisers • method of application of fertilisers • amounts of fertilisers applied and details of calibration procedures. 4.1.2 Records must show evidence that fertiliser types, amounts and application rates per hectare are: • tailored to match the soil type and the crop type • appropriate for the prevailing weather conditions (in order to avoid, eg, use of foliar nutrient sprays before rains; application of urea on a hot, dry day, etc). 4.1.3 Tissue analysis and/or soil nutrient analysis should be completed as required. 4.1.4 Nutrient application should be based on soil and tissue fertility in accordance with results of tissue and/or soil analysis, calculations of crop load and varietal traits. Depending on crop type, there needs to be routine analysis, eg, lemons and mandarins are more demanding of nutrients than some other varieties.
Encouraged 4.1.5 Growers are encouraged to use their records, application data and the results of soil and or tissue analysis to enhance soil fertility. Refer to Section 1.5.3. 4.1.6 The grower’s diary or other records should show reports of nutrition related events. All applications of soil and foliar fertilisers must be recorded. Records must include locations, date, type and quantity of fertiliser, method of application, application rate per hectare and the operator. (The diary and records form the basis by which the auditors can confirm that a nutrient management plan is being implemented.) 4.2 Crop Knowledge and Problem Solving Growers or advisers must be competent and be able to demonstrate knowledge of plant and soil nutrient requirements and correct use of nutrient inputs. This can be assessed from their nutrient management plan and diary. Required 4.2.1 Growers must demonstrate knowledge of the following: • methods for correcting plant nutritional imbalances • the risks for pests, fruit quality, soil fertility and fruit set if nutrient balance is not maintained • use of agronomy advice to resolve nutrient imbalances. Encouraged 4.2.2 Growers are encouraged to draw upon the collective knowledge of grower groups and develop methods of solving nutrient problems through diagnosis and adaptive management. The use of the nutrient diary and nutrient management plan, together with knowledge of the history of the orchard, are key tools in achieving this aim. 4.3 Fertiliser and Nutrient Spray Quality Required 4.3.1 Fertilisers and nutrient sprays must be of a food-safe, registered, reputable brand of known quality, and must be obtained from an approved supplier. (The purpose of this requirement is to reduce the likelihood of usage of inferior products that may contain contaminants.) 4.4 Fertiliser Storage Required 4.4.1 Fertiliser must be stored correctly (clean, dry location away from oils, fuels, pesticides and where there is no possible contamination of water sources). 4.4.2 Fertiliser is not to be stored in or near sheds where fresh food is handled. 4.4.3 Growers must have all hazards identified by signage in line with current regulatory requirements. 4.5 Nutrition and Soil Management Required 4.5.1 Growers must implement management practices to increase soil organic matter to improve nutrient and water retention of soil and to reduce erosion. Refer to Section 1.5.3. 4.5.2 Organic manures must be stored in an appropriate manner to reduce the risk of contaminating the environment. In line with Food Safety and Hygiene regulations, use of raw untreated human sewage is totally prohibited. Any treated human sewage or sludge used as a fertiliser in agriculture production must be supported by data proving that there are no high levels of pathogens or heavy metals or other components that will have an adverse affect on human and animal health, and soil and ground water quality. Encouraged 4.5.3 Growers must attempt to avoid pollution by heavy metals, nitrates and other potential pollutants in the manure. Analysis of manure, including nutrient values, should be undertaken. 5. Sustainable Crop Protection Philosophy Crop protection should be based on an integration of varietal selection, biological, chemical and cultural practices. This may be achieved by implementation of an Integrated Pest Management (IPM) strategy as outlined below.
1. 2. 3. 4. 5. 6. 7.
Ideally quality goals should be achieved by as minimal inputs as possible, conservation of existing natural enemies, and use of cultural practices to control most pests. Some low-level pest populations and damage should be tolerated before any external inputs to control are considered. Where possible, external input should be the release of appropriate biological control agents if available. Pesticide use should only be considered when pest populations exceed the threshold determined by monitoring and there is little or no evidence of beneficial organisms to reduce pests. Ideally pesticides should be of low toxicity to the user and other off-target beneficial organisms. They should have short residual toxicity. Pesticides of broad-spectrum activity or high toxicity to the user or off-target beneficials should be limited to extreme circumstances where the crop may be completely ruined and no other alternative is available. High toxicity pesticides that are systemic, with long residual action, should never be used.
Environmental/Cultural Considerations 5.1 Enhance biodiversity 5.2 Quarantine and hygiene 5.3 Windbreaks and companion planting 5.4 Chemical application protocols 5.5 Integrated Pest Management 5.6 Cultural/management practices 5.7 Other management practices 5.8 Alternative markets Practice and Standards 5.1 Enhance Biodiversity Generally speaking, conventional modern agricultural practices and monoculture crops create an ideal situation for pest/disease enhancement. Encouraging a greater diversity of plants, invertebrates and vertebrates in the system helps to stabilise, and therefore lower, the significance of pests and diseases. Biodiversity within ground cover species is very important to the build up and shelter of beneficial insects and mites. Beneficial predators (eg, Lacewings, Ladybirds, Hoverflies, Aphid parasites) feed on pests present in the ground covers and then move on to pest populations on the crop. Required 5.1.1 Growers are required to obtain documentation, eg, fact sheets, scientific papers, books etc, which provides information on pests and beneficials, and the role ground cover management has on their populations (eg. Colloff et al. 2002) Encouraged 5.1.2 Growers are encouraged to develop/maintain a ground cover which contains a diverse population of both broadleaf and monocot plant species. For example, Spring flowering grasses s upply pollen for beneficial above ground predatory mites. Broadleaf flowers may supply nectar for some hymenopterous parasites. Note: Light Brown Apple Moth (LBAM) is capable of increasing its population in the cover crop and moving into the cultivated crop. Some broadleaf species, such as capeweed, are favoured hosts in which the LBAM overwinter. Other hosts of the LBAM include legumes. This means that growers should encourage the ground cover to be as diverse as possible. 5.2 Quarantine/Hygiene Quarantine is extremely important on an international, state and regional basis. It can also be important on a property-by-property basis. Required 5.2.1 Growers must ensure that all imported planting material comes from a certified/accredited nursery. All bud wood should be sourced from a disease/virus free certified scheme (to prevent, for example, diseases such as Tristeza, Psorosis , etc). Utilise tolerant/resistant rootstocks for root diseases and nematode control. 5.2.2 When purchasing new trees, growers mu st ensure they are free of pest species such as nematodes and scale. It is extremely important that the trees are free of, and are treated for, Phytophthora spp. prior to receipt. Note: if chemical treatments are required to remove pests, then this should be done before trees are received.
This will reduce the chance of introducing new pest species and help to minimise the need for treatments in the orchard. 5.2.3 Pruning equipment, including hedging equipment, must be disinfected when moving between properties, varieties and different aged trees. This is especially important when moving from older trees to newer plantings as diseases, viruses and viroids (eg, Exocortis) can be transmitted via equipment. Encouraged 5.2.4 Growers should aim to skirt trees to reduce soil splash to fruit (and prevent development of Phytophthora brown rot) and damage to fruit from contact herbicides. Skirting can limit movement of pests, such as snails, Fullers Rose Weevil and ants, to the canopy. 5.2.5 Pruning of trees to re move dead wood from inside the tree canopy that carries disease spores (eg, Melanose, Anthracnose, Septoria and Colletotrichum) is encouraged. Open trees dry out more quickly; fruit colours more evenly; fruit tends to have firmer skin, and is easier to spray if required. 5.3 Windbreaks and Companion Planting Required 5.3.1 Establishment of tree, tall grass or artificial windbreaks and/or companion plants is required. Natural or artificial windbreaks will reduce wind rub. Fewer wind-induced blemishes will result in clearer fruit, which could allow for a greater tolerance to pest blemishes. Windbreaks can help reduce dust and may capture spray drift, thereby helping to maintain an environment that is suitable for beneficials. Encouraged 5.3.2 Windbreaks, roadside vegetation, natural vegetation, companion plantings and amenity areas should be considered an asset that can add diversity to the property. By preserving and improving these areas the grower can provide alternative food/shelter areas for beneficials and bird species. Note: these areas should be regularly monitored to ensure that ants and vermin (rabbits, hares, foxes etc) are not using the areas as breeding points. 5.3.3 When selecting windbreak species and/or companion plants, growers are encouraged to make an informed and relevant decision supported by documentation such as Dames & Moore, or in consultation with specialist groups such as Trees for Life, Greening Australia or PIRSA. Due consideration should be given to the potential for non-indigenous plant species to become environmental weeds. 5.4 Chemical Application Protocols Required 5.4.1 Growers must demonstrate a clear understanding of chemical resistance and have in place a ‘Resistance Management Strategy’. (For further detail refer to Citrus Growing Manual: a manual for quality decisionmaking or PIRSA fact sheets.) 5.4.2 Growers must be able to demonstrate knowledge of Maximum Residue Limits (MRLs), label rates and withholding periods, and must have copies of the most recent MRL documentation. (Refer to Citrus Growing Manual: a manual for quality decision making, Market Specifications section, pp11-23, or NRA website at www.nra.gov.au) Encouraged 5.4.3 Growers are encouraged to document their ‘Resistance Management Strategy’. 5.5 Integrated Pest Management Growers are encouraged to follow the Integrated Pest Management (IPM) guidelines as per 'Concepts of integrated pest management (IPM)', pp 14-15, Smith et al., (1997) Citrus Pests and their Natural Enemies: Integrated Pest Management in Australia) Identification/Monitoring/Thresholds/Control Options 1. Young trees Any pest, which can reduce the health and growth of the tree, should be considered a serious pest. To build an environment conducive to IPM, healthy trees and good canopies to harbour beneficials are essential. Monitoring is Essential Controls Controls must be in place for scales, soft scales, earwigs, ants, leaf miner, aphids and crusader bugs. Growers may need to choose chemical options initially but are advised to choose wisely to avoid residual problems.
Hand spray to avoid drift. 2. Bearing trees Spring - Kelly's Citrus Thrips (Pezothrips (formerly Megalurothrips) kellyanus) - Light Brown Apple Moth (Epiphyas postvittana) scarring/fruit damaging pests in spring Katydid (Caedicia spp.) may require chemical intervention. - Spined Citrus Bug (Biprorulus bibax) (Refer to Citrus Pests and their Natural Enemies: Integrated Pest Management in Australia for information, monitoring and thresholds.). Monitoring is Essential Controls Control only if thresholds have been exceeded. Only lemons/limes require chemical control once outside spring season. Spring/Summer/Autumn - Non scarring/fruit damaging Red Scale (Aonidiella aurantii), Soft Brown Scale (Coccus hesperidum), Black Scale (Saissetia oleae), Citricola Scale (Coccus pseudomagnoliarum), Cottony Cushion Scale (Pulvinaria polygonata); Black Citrus Aphid (Toxoptera citricida), Brown Citrus Aphid (Toxoptera aurantii), Melon Aphid (Aphis gossypii), Spiraea Aphid (Aphis spiraecola); Citrophilous Mealybug (Pseudococcus calceolariae), Long-tailed Mealybug (Pseudococcus longispinus); Leafhopper (Empoasca smithi); Citrus Rust Mite (Phyllocoptruta oleivora); Australian Citrus Whitefly (Orchamoplatus citri); Citrus Leaf Miner (Phyllocnistis citrella). Monitor - as per Chapter 25, pp 201-225, Citrus Pests and their Natural Enemies: Integrated Pest Management in Australia. Controls - naturally occurring beneficials - limited to oil sprays - release of natural enemies - chemical control only in extreme situations where tree health will suffer. Conduct regular tests for nematodes (Citrus Nematode (Tylenchulus semipenetrans), Stubby Root Nematode (Paratrichodorus spp.), and Root Lesion Nematode (Pratylenchus spp.) and root rots (Phytophthora, Pythium, Fusarium etc). Apply preventative programs where required and fungicides and nematicides only as a last resort. Required 5.5.1 Growers must own a copy of the publication Citrus Pests and their Natural Enemies: Integrated Pest Management in Australia, (1997) HRDC, DPI Queensland Information Series QI97030; have read it; and must be able to give a practical, recent example of when and how their IPM program was implemented. 5.5.2 Growers must be able to present evidence of self-monitoring or commercial monitoring as part of their IPM program. 5.5.3 Growers must be able to give practical examples of use of biological control, cultural control or, if applicable, chemical control, and beneficial insect releases as part of their IPM program. Encouraged 5.5.4 Growers are encouraged to attend IPM workshops. Participation by growers and their properties in IPM research programs is encouraged. 5.5.5 Growers are encouraged to show evidence of having examined the performance of their spray equipment (eg, fluorescent dyes, water sensitive papers etc). 5.5.6 Growers should attempt to have unknown insects identified by entomologists, develop a family/species list, and develop a species collection. 5.5.7 Growers are encouraged to demonstrate that, where appropriate, they accept higher pest thresholds in the interest of medium and long-term sustainability. 5.6 Cultural/Management Practices The cultural/management practices adopted by a grower can have a significant influence on the level of pest problems experienced. Required 5.6.1 Growers must be aware of which weed species encourage pests. A Weed Management Strategy should control these pest weed populations, avoid monocultures and encourage cover crops to be as diverse as possible. Growers need to be able to demonstrate a Weed Management Strategy that encourages beneficials or discourages pests and diseases.
5.6.2 Growers need to demonstrate an understanding of the interrelation between crop nutrition and pest populations because crop nutrition can play an integral role in the management of crop protection. For example, a nitrogen overdose can allow pest populations such as scales to breed up at an accelerated rate. 5.6.3 Growers must combat dust problems by limiting the number of roads that are unsealed or without ground cover. 5.7 Other Management Practices External influences impacting on successful Integrated Pest Management programs Successful IPM programs can be adversely affected by influences from beyond the boundaries of the orchard and beyond the control of orchard management. Dust from unsealed district roads which carry high traffic loads, carelessly applied spray which results in drift trespassing from adjoining properties, indiscriminate burning of rubbish creating a smoke hazard, and possible intrusion by contaminated rain water or irrigation run-off are examples of these adverse impacts. OHS&W Legislation, Fire Control measures and Spray Trespass Regulations can assist orchard management to reinforce satisfactory behaviour by persons outside of the orchard. Required 5.7.1 Growers need to demonstrate that every effort is made to inform, educate and detail the effects of these possible intrusions to adjoining neighbours or public authorities to minimise the impacts to IPM programs and to workplace employees on the orchard. 5.7.2 Growers must have a clear understanding of the legal means, which could assist in overcoming the adverse influences coming from beyond the property boundary. Encouraged 5.7.3 Growers can develop a defined Plan of Activities with neighbours (Rural or Public Authority). This will enable all parties to be aware of critical pest or disease periods and possible impacts from unplanned activities and to have a planned approach to reducing potential conflicts. 5.8 Alternative Markets Required 5.8.1 If, in any particular year, the grower has an increased pest population, the grower should have in place a strategy to find alternative markets for blemished fruit, and may be able to increase their pest population tolerance levels. 6. Ground Cover Plant Management Philosophy Ground cover plant management in best practice citrus orchards must encompass the principles of control of pest plants with techniques of management using desirable and dominant plant species, natural foraging and minimal herbicide inputs. Essential Prerequisites Growers must have achieved competency in documentation of orchard activities, including a Quality Assurance System, must have been accredited with a Chemical Users Certificate, and must be competent in the keeping of a comprehensive Spray Diary. Practice and Standards 6.1 Knowledge and Understanding of Principles Required 6.1.1 Growers need to demonstrate a clear understanding of beneficial and pest plants and their impact on both horticultural crops and desirable plant growth. 6.1.2 A good understanding of pests and disease tolerance or resistance of plant species being used in the groundcover situation is required. 6.1.3 Growers must demonstrate an understanding of the establishment, ma intenance and nutritional requirements of desirable plant species. 6.1.4 Growers need to have in place as part of their Quality Assurance System a purchasing policy to buy seed only from an approved supplier.
Encouraged 6.1.5 Growers should obtain a pest plant manual with detailed descriptions. 6.1.6 Growers are encouraged to acquire a plant identification manual and/or other literature (eg, consultants’ reports), which details beneficial organisms. 6.1.7 Growers are encouraged to collect additional documented data or fact sheets that outline the nutritional requirements of desirable plant species. 6.1.8 Obtaining a plant manual or consultants’ reports detailing programs beneficial to desirable organisms and plants is encouraged. 6.2 Natural Foraging Required 6.2.1 Growers who rely on natural foraging of weeds by introduced poultry and other animals must be able to demonstrate an understanding of the requirements for managing and housing these animals so as not to cause stress or trauma to the animals. Growers must also demonstrate that no undue risk to consumers’ health exists from contamination of horticultural produce grown in circumstances with natural foraging animals. 6.2.2 Growers using natural foraging methods for pest weed control must maintain a diary with adequate records to show animal movement into or out of the orchard. Encouraged 6.2.3 Growers are encouraged to collect documented reports/data on animal husbandry and health. 6.3 Control and Management of Pest Species Required 6.3.1 Growers must understand the potential for planting desirable weeds or plants to provide a habitat for beneficial insects, to provide a deterrent to pest insects or to provide dominance over pest weeds. This includes the potential for companion plantings in horticultural crops. Records of these activities should be kept. 6.3.2 Growers must understand the methods of weed control that will produce the most effective results, employ efficient techniques and ensure that the activities will not impact adversely on the horticultural crop and the immediate or regional environment. 6.3.3 Regulations require that a comprehensive and accurate Spray Diary must be kept for audit purposes. 6.3.4 As required by current regulations, growers must have a clear understanding of calibration methods for chemical weed control spraying units. Growers must be able to demonstrate knowledge of safe handling of chemicals, and safe operating conditions for any chemical weed control program. 6.3.5 Growers must be able to demonstrate knowledge of chemicals that can be used in weed control with particular attention to any impact on horticultural crops, soil structure, soil biodiversity, insect pest management, native vegetation and natural fauna. 6.3.6 Growers must demonstrate their knowledge of new information and technology resources as they become available for pest weed control and management. 6.3.7 Growers who rely on soil tillage programs to control pest weeds need to demonstrate knowledge of the impacts of any such program on soil structures, soil biodiversity and horticultural crops. Records of these tillage activities should be kept. 6.3.8 Growers are required to explain the process for reaching a decision to implement a weed control spraying program or a decision to undertake a tillage activity. Encouraged 6.3.9 Growers should show an extended interest and commitment to gathering any new information on pest weed control and management. 6.3.10 Growers are encouraged to perform trials that indicate innovative management practices. 6.3.11 Growers are encouraged to undertake an Integrated Pest Management course. 6.4 Genetically Modified Ground Cover Plant Species Required 6.4.1 Growers should have a broad understanding of the uses or restrictions of use of genetically modified plant species and additives, and the implications of this on the production and market opportunities for the main citrus crop. Encouraged 6.4.2 Growers are encouraged to obtain a summary of latest detailed literature with balanced views on the GMO debate.
Addendum to Section 6 - Ground Cover Plant Management Consultants’ reports relating to soil use, soil profiles, soil compaction, soil/water relationships, pest incidence and any other issue must be kept and made available for audit. 7. Social and Environment Philosophy Biodiversity in farming systems is essential to sustain the environment—physically, socially and financially. Growers must: § protect remnant native vegetation on their properties § maintain and increase biodiversity on their properties especially by utilizing locally native species § minimise the negative impact on local environments by utilizing inputs as efficiently as possible and thus minimising wastage and pollution § provide a safe and healthy work environment for employees § ensure the safety of produce § abide by any current industry and environmental legislation. Growers should aim to: § be involved in community groups which uphold the above philosophy § Pursue knowledge and research into methods that can help efficiently achieve higher biodiversity within orchards either through growers' own means and networks or with the involvement of research organizations § plan, design and manage their properties in a way that upholds the above philosophy. Practice and Standards 7.1 Product Safety Required 7.1.1 Growers must have in place a Safe Quality Food - SQF 1000 or equivalent third party audited system for citrus. Encouraged 7.1.2 Growers should attempt to source external products from businesses with a Quality Assurance System in place. 7.2 Safe and Healthy Environment Recognition is to be given to growers’ efforts beyond legislative requirements in providing a safe, healthy and pleasant workplace. This is covered in the Safety in Horticulture: An OH&S Resource Kit. Required 7.2.1 Growers must comply with all Occupational Health and Safety policy. 7.2.2 Growers must utilise an OHS&W manual (as per Safety in Horticulture: An OH&S Resource Kit). 7.2.3 The workplace environment must comply with current legislative requirements. Encouraged 7.2.4 Growers are encouraged to create, for example, a learning environment or a pleasant ambience for their employees and others. 7.3 Planning and Design Recognition is to be given to a grower’s completion of appropriate business and environment management system plans, as this demonstrates long-term commitment. Required Essential components are largely covered by the other ’essential’ requirements in the rest of the audit (eg, Soil and Irrigation Management, Integrated Pest Management and Nutrient Management). Encouraged 7.3.1 Growers should aim to prepare a Business plan. 7.3.2 Preparation of a Property Management Plan (as per PMP training) or equivalent is encouraged. 7.3.3 Growers are encouraged to attend a Permaculture Design course and to prepare a permaculture plan for their property.
7.3.4 Growers may consider opportunities to value add and diversify existing products (eg, the development of niche markets and product processing; complimentary products; self marketing; companion plants and their products; composting, mulching or using old trees as firewood instead of burning off, etc). 7.4 Hygiene Required 7.4.1 The orchard must have a demonstrated history of good orchard hygiene practice with appropriate records being kept. 7.5 Biodiversity Enhancement and Generation/Creation Recognition is to be given to the grower’s commitment to the many and varied aspects of this Section. Required 7.5.1 Protection of remnant vegetation as required by current legislation is essential (including management of scheduled pests, weeds and diseases). 7.5.2 A plan must be in place for revegetation with native species (preferably local species where appropriate), of available land, roadside verges and land not suited to irrigated horticulture. 7.5.3 Growers must have a plan in place for control of feral pests. Encouraged 7.5.4 Growers may attempt to appropriately enhance areas of remnant vegetation (eg, fencing of relevant areas to protect from vermin). 7.5.5 Growers are encouraged to develop an awareness of existing biodiversity (eg, lists and/or recognition of birds, native plants, macro and micro invertebrates, reptiles, micro flora etc), that exist on the property and surrounds. 7.5.6 Growers should attempt to document progress occurring with revegetation of areas identified in Section 7.5.2 above. (This could include multi species windbreaks, fauna habitat, water table mitigation and overall biomass production). 7.5.7 Growers should take conscious steps towards creating greater biodiversity, either through improving or modifying current cultural practices or through purposely adding to the existing suite of flora and fauna in a sustainable manner. This may be either on a so-called ’macro’ (or visible) scale or on a ’micro’ (less visible) scale. The macro scale would include vertebrates and plant species. The micro scale may include any appropriate range of invertebrates (as well as vertebrates), bacteria, fungi and other plants. 7.5.8 Growers should progress towards control of feral pests (eg, trapping of cats, baiting of rabbits and foxes, and rabbit warren management). 7.5.9 Growers should aim to progress towards non-competitive polyculture (where different species of plants and animals occupy the same physical environment with minimal competition and where synergism is maximised). Examples include agro forestry for windbreaks, habitat, shade and timber production; interplanting of different fruit tree species; use of grazing animals within the orchard; and the development of other niche products. 7.6 Community Involvement Involvement is encouraged in community projects or groups which are endeavouring to preserve and enhance natural resources for future generations. Encouraged 7.6.1 Growers should aim to become members of a locally active conservation based organization. 7.6.2 Growers should invest in membership of other conservation based organizations (eg, Landcare Australia, Wetland Care Australia, Trees for Life Inc, Australian Conservation Foundation, Greening Australia, Birds Australia, Local Action Planning groups, etc). 7.6.3 Active involvement in conservation groups (eg, tree planting groups) is encouraged. 7.7 Education Required 7.7.1 Growers must demonstrate training of employees and business members to understand their enterprise philosophies. 7.7.2 Growe rs must educate/train staff so that they understand relevant cultural practices in an environmental context in relation to growing citrus.
Encouraged 7.7.3 Growers should aim to attend CITT (Citrus Information Technology Transfer) and other technology transfer group meetings relevant to management practices. 7.7.4 Involvement with relevant research activities is encouraged. 7.7.5 Growers are encouraged to become involved with educating people about biodiversity, conservation and efficient use of resources. 7.7.6 Growers should attempt to provide ongoing training to staff. 7.7.7 Growers should maintain and upgrade their knowledge of environmental issues and practices relating to their farming system (eg, attendance at environmental field days, subscription to environmental magazines or membership of one of the groups listed in Section 7.6). 7.7.8 Growers should undertake their own experimentation and research that is related to natural resource management (eg, water use efficiency, canopy management, waste management, etc). 7.7.9 Growers should attempt to disseminate relevant knowledge to other growers and members of the community (eg, hosting field walks, demonstrations, speaking at events, providing information on findings to newsletters, journals etc). 7.8 Energy Recognition is to be given to growers seeking ways to improve efficiency of power and fuel usage. Required 7.8.1 Growers must ensure safe and secure storage of fuel. 7.8.2 Growers should maintain machinery and pumps in good order (as per OHS&W records for machinery, eg, not leaking oil, not blowing excessive smoke, etc). 7.8.3 Growers should use appropriately sized machinery for particular jobs (eg, use an appropriate sized tractor for slashing or machinery which will minimise the number of passes needed). Encouraged 7.8.4 Growers should use night rate for electricity where possible, especially for irrigation. 7.8.5 Growers should attempt to investigate and implement renewable energy sources. 7.8.6 Reducing energy requirements, conserving energy and engineering energy savings into structures and activities should be priorities. 7.8.7 Growers should keep updated records of machinery services and maintenance. 7.9 Output (non-crop) Management Non-crop output relates to all ’materials ’ brought onto or produced on the property that do not end up as saleable product being managed or disposed of in a sustainable manner. It is vital to promote a system that does not “leak”, that is, all waste products are maintained (where possible) on the property (for example, spray drift, mulching or composting instead of burning off, drainage outflows, irrigation run-off and disposing of unwanted toxic materials in accordance with current legislation). Required 7.9.1 Growers must minimise drainage outflows. Use on-site where possible. 7.9.2 No spray drift (as evidenced by spray and weather records) is to trespass beyond property boundaries. 7.9.3 Growers must minimise stocks of toxic materials and dispose of unwanted toxic materials and containers via legislatively required and appropriate means (eg, “Chemcollect”). Safe and secure storage of toxic materials as per OHS&W legislation is essential. Encouraged 7.9.4 Minimal burning off of prunings is encouraged (eg, using larger prunings or trees as a sustainable source of firewood; mulching of smaller material). 7.9.5 Growers may wish to explore modifying old machinery or old materials for new purposes. 7.9.6 Growers are encouraged to use drainage water to irrigate salt tolerant plant species (providing this doesn’t cause site degradation). 7.9.7 Growers may wish to investigate the use of planted windbreaks to attempt to minimise spray drift. 7.9.8 Growers should aim to implement recycling programs for any unwanted materials. Section 7 - Appendix Environmental balance sheet The development of an environmental balance sheet is a long-term goal for creating an environmental debits and credits measuring system for a grower's overall impact on the environment. Another way of interpreting this is to consider for example, how many calories of energy, or how much embodied energy, it takes to grow, harvest,
package, transport and market an orange to a consumer in the United States? This may be one way in which growers can attempt to develop a useful and effective indication of this issue and how it ultimately impacts on the environment. Credits could include: § Crop production § Soil biomass § Plant biomass (includes crops, ground covers, windbreaks, etc) § Consumption of carbon dioxide and production of oxygen § Measure of biodiversity § Social impact (eg, creation of jobs and community involvement) § Other Debits could include: § Off-site impacts § Water usage (alternative uses for the water) § Fossil fuels consumption § Infrastructure and machinery (eg, what is the true energy cost of mining the materials and manufacturing them into a new tractor) § Direct energy consumption (eg, contribution to greenhouse emissions, other pollutants) § Indirect energy consumption (eg, energy used in the manufacture of inputs and energy used in transporting and storing finished products) § Soil erosion and degradation (eg, loss of structure, salinisation) § Other NOTE: due recognition should be given to the fact that logistically it is harder for a smaller landholder to be involved in as many categories as a larger landholder. However, the actual ’involvement’ per unit area could be higher for a smaller landholder. References and Recommended Reading Colloff, M.J., Fokstuen, G. and Boland, T. (2003) Toward the Triple Bottom Line in Sustainable Horticulture: Biodiversity, Ecosystem Services and an Environmental Management System for Citrus Orchards in the Riverland of South Australia.CSIRO Entomology, Canberra. Dames & Moore - NRM (July 1999) Alternative Revegetation Through Permaculture Design Concept Designs and Report for the River Murray Local Action Planning Groups. Irrigated Crop Management Service, PIRSA Rural Solutions (2001) Drip Irrigation Manual. McIntyre, K. & Jakobsen, B. (1998) Drainage for Sports Turf and Horticulture, Horticultural Engineering Consultancy, Kambah, Australia. Moulds, G. & Tugwell, B. (1999) Citrus Growing Manual: a manual for quality decision making, Horticultural Research Development Corporation. Primary Industries South Australia & the River Murray Water Resources Committee (1997) The RiverCare Irrigators Manual Smith, D., Beattie, GAC., & Broadley, R. (1997) Citrus Pests and their Natural Enemies: Integrated Pest Management in Australia, Information Series QI97030, Department of Primary Industries and Horticultural Research and Development Corporation, Queensland. Smith, D., Broadley, R., Feutrill, C., Beattie, A., & Freebairn, C. (1997) Citrus pests: a field guide. A Companion to Citrus Pests and their Natural Enemies: Integrated Pest Management in Australia, Information Series QI97092, Department of Primary Industries and Horticultural Research and Development Corporation, Queensland. WorkCover Corporation (31 July 2000) Safety in Horticulture: An OH&S Resource Kit for the Citrus, Grape, Stonefruit and Almond growing industry in the Riverland of South Australia, Version 1. (Updated versions available through the WorkCover Corporation's Internet site at www.workcover.com) www.agric.nsw.gov.au (2000) ‘Preparing an irrigation and drainage management plan’, Richard Swinton, Resource Management Officer, Grafton.
Peer-audited Certification Process The Citrus Sustainability Group Audit Sheet has been produced as a tool for peer-audited certification. The notation system has been developed as an easy way to cross-reference the Audit Sheet with the Manual. The scoring system is based on ratings from zero to three (0 - 3). An auditor will mark the grower's response to each question on the Audit Sheet as one of the following: § Zero (indicating that the grower has not satisfactorily met the criteria), § One (indicating that the grower has met the criteria in part but needs to improve further), § Two (indicating that the grower has met the criteria but could improve), § Three (indicating that the grower has fully met the criteria). To pass the ‘Required’ column for each section on the Audit Sheet, the grower needs to achieve two things; 1. a score greater than zero on every question (a mark of zero will only be counted if the majority of the auditors have marked zero on the same answer), and 2. A minimum of eighty percent of the total score in each of the seven audited sections. The maximum score and eighty percent of that score can be found in the total row at the end of each section on the Audit sheet. Some of the questions on the Audit Sheet will not be applicable to some production systems (eg, organic growers). If this is the case, the auditors will mark N/A on the Audit Sheet and the total/percentage at the end of that section will be changed accordingly. The 'Encouraged' sections in the Audit Sheet are to be marked with the same zero to three scoring system. There is no pass/fail percentage for the 'Encouraged' section as this part of the audit process has been incorporated as an educational and motivational tool. Example of an audit sheet for Manual of Best Practice. March 2002 Draft No. 1
1 1.1 1.1.1
Required Soils Records Map or recent aerial photographs of property Data Soil maps and/or topographic (contour) maps of entire property
Incorporation of maps and property details into farm management software
Soil survey to determine physical properties
Map showing where samples taken and soil properties of each site
Awareness of methods and services available to measure soil nutrient and biological status Monitoring to demonstrate soil resource is not degrading Observation and documentation of plant health and changes to plant diversity and biodiversity Chemical soil analysis for nutrients pH and salinity EC
1.3.4 1.4 1.4.1
Nutrient Inter-relation Understanding of how soil pH influences availability of nutrients and by what management practices this is influenced
Soil Management Management practices that maintain or increase the organic carbon levels in the soil
Observation, documentation and correction of nutritional problems
Specialist advice on problem areas
Planting of cover crops and mulching to improve nutrients and friability of the soil
Degraded Area Management Maps showing areas degraded by compaction, water run-off, erosion and salinity
Measurement of organic carbon levels in the soil and its change over time
Identification and amelioration of soil compaction, by adding organic matter/composts, gypsum or deep ripping where appropriate Minimize tillage and compaction to conserve soil structure
1.6.3 1.7 1.7.1
Alternative Planting Understanding of the need to select the appropriate crop and rootstock for a soil type
Pest and Disease Awareness Awareness of the risks of soil pests/diseases in planting material, manures, organic matter/composts or soils Implement policy of buying only accredited products from approved suppliers Importation of Pests Awareness of the possibility of pests and diseases and unwanted plant species being carried onto the property by people and vehicles
1.10 Soil Populations 1.10.1 Understanding of the role that soil biota and ecosystems play in the health of the soil
Use of soil survey data to select areas suitable for various crops/rootstocks
Seek help from advisers or plant nurseries
Chemical and disease status reports from approved suppliers of materials being imported
Signs or verbal indications to warn visitors that, due to pest and disease control, access to the property is restricted
Where practical, restrict entry with fences and use wash bays and foot baths or foot covers
1.10.2 Understanding of conditions favourable/unfavourable to good soil biological health (refer to Manual Section 1.10.1) 1.10.3 Obtain information on the management of soil biodiversity and ecosystems 1.10.4 Observation by grower or specialist of micro biological content and macro biological content of soil 1.10.5 Development of a management plan to maintain and improve soil biodiversity and ecosystem function