DEPARTMENT OF PRIMARY INDUSTRIES Managing Your Soil a field day for organic and conventional growers
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Department of Primary Industries - Sunraysia Horticultural Centre
Soil Management Field Day, April 30, 2003 Programme:
9:30 AM Registration
10:00 AM Introduction to the day SallyAnn Henderson, Vegcheque
10:05 AM Organic industry overview David Madge, DPI Victoria, Irymple Research Scientist, IPM & Organic Horticulture 10:20 AM Introduction to soils Chris Alenson
10:45 AM Soil microbiology Darryl Nelson, DPI Victoria, Rutherglen Research Scientist, Microbiology 11:10 AM Soil biodiversity study Graeme Sanderson, NSW Agriculture, Dareton Research Horticulturist, Citrus & Vines 11:25 AM Tea Break 11:45 AM Soil management Chris Alenson
12:15 PM Organic vegetables - Sue Dickinson, Vinifera
12:30 PM Organic vines - Andrew Jones, Irymple
12:45 PM Stretch break 12:50 PM Organic citrus - Robert Ridgwell, Palinyewah
1:05 PM SHC organic project & results Christiane Jaeger, DPI Victoria, Irymple Research Officer, Organic Horticulture 1:20 PM Lunch 2:05 PM In field - vegetable research Christiane Jaeger
2:25 PM In field - soil assessment Chris Alenson & Darryl Nelson
3:00 PM Open discussion panel 3:30 PM Tea Break & Close
This field day is presented as part of the Department of Primary Industries project ’Sustainable Organic Production Systems’, funded by the Victorian Government’s ’Naturally Victorian’ initiative.
Support for the field day was generously provided by the Rural Industries Research and Development Corporation.
This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. © State of Victoria Department of Primary Industries April, 2003.
2 An overview of the organic agriculture industry in Australia
David Madge Research Scientist DPI, Sunraysia Horticultural Centre, Irymple
Size of the Australian organic industry The total annual value of organic agricultural production in Australia is approximately AUD $240million, with about 40% of this derived from exports. Our main export markets for organic produce are the U.K., Germany and Japan. In 2001, Australia had 1,380 certified organic properties (1.4% of all Australian farms), covering 10.5 million Ha (2.31% of all agricultural land in Australia). This is the largest area of any country and represents about half of the world’s certified organic land. However, it is mostly extensive, low-intensity grazing land. For interest, some global statistics on organic farming are included on a separate handout.
Global Market growth During much of the 1990’s, the global organic food market grew by about 20% per year. Current predictions are that from 2003-2005, the annual growth in most markets will be between 5 and 15%, with Ireland, USA and Canada reaching up to 20%.
The Australian organic industry The backbone of the organic industry in Australia is comprised of the many growers, processors and marketeers who work to produce and promote organic food and other products for the domestic and international consumer. A number of organisations also play an important role in supporting and regulating the industry. These are the Australian Quarantine Inspection Service (AQIS), the Organic Produce Export Committee (OPEC), the Organic Federation of Australia (OFA), organic certification organisations, the Rural Industries Research and Development Corporation (RIRDC) and other Rural Industry Research Corporations, and state agricultural departments.
AQIS - Australian Quarantine Inspection Service AQIS is the federal government body that controls the exporting of all produce from Australia. This includes organic produce. The Export Control Act (1982) and Export Control Orders (1997) require that ’Organic’, ’Bio- Dynamic’ or similarly labelled produce for export, must be produced under a licence issued by one of the organic certification organisations approved by AQIS (listed below). This requirement does not apply to Australian produce marketed as organic within Australia - an issue that is being pursued by the OFA (see below).
Apart from its regulatory role, AQIS has also worked with the Australian organic industry, through OPEC, to develop the National Standard for Organic and Biodynamic Produce. This Standard documents the minimum requirements to be met by produce intended for export as Organic or Bio-Dynamic. The National Standard sets the baseline for standards developed by the certification organisations themselves.
Contact: Australian Quarantine Inspection Service GPO Box 858 Canberra ACT 2601 Tel: (02) 62716638 Fax: (02) 62723238 Email: [email protected] Internet: www.aqis.gov.au/organic
OPEC - Organic Produce Export Committee OPEC is the principal advisory forum for AQIS to consult with the Australian organic and biodynamic industries on operational and administrative processes and market access issues. OPEC meets once a year in Canberra and consists of: • one representative from each of: AQIS Food Inspection Operations; Organic Federation of Australia; International Federation of Organic Agriculture Movements (IFOAM); AQIS Market Maintenance Group; Rural Industries Research and Development Corporation and AQIS Organic and Biodynamic Program, • one representative from each of the Approved Certifying Organisations, and • representatives of the Standing Committee on Agriculture and Resource Management (SCARM).
OPEC’s brief is to consider: • financial matters related to levels of apportionment of AQIS charges to the organic industry sector; • strategic directions for AQIS relevant to the organic/biodynamic industry; • key performance indicators, such as efficiency and effectiveness of the program;
3 • any matter relating to the production, processing, packaging and transportation of organic/biodynamic export produce; • the interpretation and application of importing country requirements and requirements under the Export Control Act and relevant Orders; • matters relating to export documentation for organic/biodynamic produce; and • any other relevant matter between the Australian organic/biodynamic industry and AQIS.
Importantly, OPEC is the custodian of the National Standard for Organic and Biodynamic Produce, and an OPEC- appointed standards subcommittee reviews and revises the Standard. The revision process is based largely on industry input and consultation. It is then OPEC’s role to approve the revision. Such a revision was completed in December 2002 and the revised Standard is available from AQIS.
Contact: Organic Produce Export Committee c/o AQIS (see above)
OFA - Organic Federation of Australia The OFA is the peak industry body for the Australian organic and biodynamic industry. Its board comprises representatives of certification organisations, organic farm inspectors, consumers, education and extension, IFOAM, and industry sectors such as livestock and horticulture. The aims of the OFA are to: • make food and fibre consumers aware of the benefits of food supplied by the Australian Certified Organic Industry; • encourage the adoption of organic farming systems; • actively lobby and liaise with government to develop policy that supports organic farming systems that deliver environmental, social justice and health benefits; and • stop the spread of genetically engineered organisms which are not proven safe and may contaminate organic and biodynamic farms.
The OFA has developed a strategic plan with the following six main components: • encouraging conversion; • Farmbis-registered three day ’conversion to organic’ training package now available; • Farmbis-registed BD programs run by Bio-Dynamic Agriculture Australia; • facilitation of organic research and development; • communicating the benefits of organic agriculture - Education programs aimed at: • industry orientation for decision makers, government departments, media, research and development corporations, key industry organisations; • consumer awareness. • developing industry policy - Domestic regulation and harmonisation of the standards. (This is essentially an international issue that has implications for traders, growers and certification bodies); • enhancing environmental sustainability - Establishment of organic certification as a relevant and workable certification program having the standing and acceptance of Environment Management Systems; • professional image - Representation of the organic industry on GMO discussions, Federal committees, and nation-wide industry co-ordination.
The requirement for certification of produce marketed as organic only applies to exported produce as mentioned above, despite attempts by the industry to have the same requirement applied to produce in domestic markets. Currently the Government will only support industry ’self regulation’. As a result, the OFA has initiated discussions on the possible development of a self-managed Code of Conduct for the Australian organic industry, which would require that produce marketed domestically as organic or similar, be covered by organic certification.
Contact: Organic Federation of Australia Box Q455 QVB Post Office Sydney NSW 1230 Tel: (02) 9299 8016 Fax: (02) 9299 0189 email: [email protected] Internet: www.ofa.org.au/
Organic Certification Organisations The organisations listed below operate organic certification schemes approved by AQIS. The certification schemes give consumers some confidence in the integrity of certified produce, as they involve publicly-available documented standards on acceptable production methods and inputs, property inspections, production and marketing audits and some produce testing for chemical residues. This list was current as at 22 April, 2003.
4 Organisation name/address Contact details Bio-Dynamic Research Institute (BDRI) Phone: + 61 3 5966 7333 Post Office POWELLTOWN 3797 Fax: + 61 3 5966 7433 Main Rd POWELLTOWN 3797 Contact: Frances Porter or Alex Podolinski Biological Farmers of Australia (BFA) Phone: + 61 7 4639 3299 Post Office Box 3404 TOOWOOMBA VILLAGE FAIR 4350 Fax: + 61 7 4639 3755 Level 1, 456 Ruthven St TOOWOOMBA 4350 E-mail: [email protected] Contact: Bob Rabbe or Quentin Kennedy URL: www.bfa.com.au National Association for Sustainable Agriculture Australia (NASAA) Phone + 61 8 8370 8455 Post Office Box 768 STIRLING 5152 Fax: + 61 8 8370 8381 Unit 7, 3 Mount Baker Rd STIRLING 5152 E-mail: [email protected] Contact: Lyn Austin or George Devrell URL: www.nasaa.com.au Organic Herb Growers of Australia (OHGA) Phone: + 61 2 6622 0100 Post Office Box 6171 Sth LISMORE 2480 Fax: + 61 2 6622 0900 Southern Cross University Crawford Rd LISMORE 2480 E-mail: [email protected] Contact: Magda VerBeek or Kenrick Riley URL: www.organicherbs.org Organic Food Chain (OFC) Phone: + 61 7 4637 2600 Post Office Box 2390 TOOWOOMBA 4350 Fax: + 61 7 4696 7689 Lamascotte Kelvinhough Boodua Rd BOODUA via OAKEY 4401 E-mail: [email protected] Contact: Marge Will or Ivy Inwood URL: www.organicfoodchain.com.au Safe Food Production Queensland (SFPQ) Phone: + 61 7 3405 4800 Post Office Box 440 SPRING HILL 4004 Fax: + 61 7 3253 9840 12 Helen St NEWSTEAD 4006 E-mail: [email protected] Contact: Phil Pond URL: www.safefood.qld.gov.au Tasmanian Organic-dynamic Producers (TOP) Phone: + 61 3 6266 0330/ Post Office Box 434 MOWBRAY HEIGHTS 7248 + 61 3 6368 1497/1227 1333 Lonnavale Road LONNAVALE 7109 E-mail: [email protected] Contact: Peter deVries or Joe Cretschmann
The organic production/processing standards produced by these certifying organisations provide a good basic guide to the principles and practices of organic agriculture. These standards should be one of the first sources of information referred to by growers who are considering converting to organic management. A good understanding of the relevant standard is important, as compliance with the standards is necessary for the maintenance of organic certification by producers, processors and other certified operators.
RIRDC - Rural Industries Research and Development Corporation RIRDC is a statutory Corporation established by the Commonwealth Government in July 1990 to work closely with Australian rural industries on the organisation and funding of their R&D needs. The Corporation works largely with new or emerging rural industries that are not catered for by commodity-focused R&D corporations such as Horticulture Australia or the Grape and Wine Research and Development Corporation.
Key strategies for RIRDC’s organic sub-program are: • Address strategies and targets published in the R&D Plan 2001-2006. • Document and develop new organic system designs appropriate to Australia. • Increase awareness of new and existing successful plant and animal nutrition methodologies. • Identify and develop new understandings of integrated soil management techniques. • Identify and overcome structural, technological, economic and social impediments to conversion. • Document successful processes for conversion in a variety of industries. • Promote policy and standards-setting processes that deliver market access based on verifiable objective equivalence of certified products while recognising the uniqueness of Australian production systems. • Foster industry development.
During 2002/03, RIRDC’s budget for organic research projects was about $275,000. The current projects involve alternative crop protection products, sugar production, education and extension (including this field day). The RIRDC website is a good source of information on organic research in Australia, and carries many free reports and information sheets. It is well worth a visit.
Contact: Rural Industries Research and Development Corporation Box 4776 Kingston ACT 2604 Tel:(02) 62724539 Fax:(02) 62725877 email: [email protected] Internet: www.rirdc.gov.au/programs/org.html 5 Other Research Corporations Commodity-focused research corporations such as the Grape and Wine Research and Development Corporation and Grains Research & Development Corporation also fund research into organic production methods, market potential, education and other issues related to their specific industry.
Grape and Wine Research and Development Corporation Box 2592 Kent Town Business Centre Kent Town SA 5071 Tel:(08) 82229266 Fax:(08) 82229267 Email : [email protected] Internet : www.gwrdc.com.au
Grains Research & Development Corporation Box E6 Kingston ACT 2604 Tel: (02) 62725525 Fax: (02) 62716430 Email: [email protected] Internet: www.grdc.com.au
State Agriculture Departments The State Government agriculture departments around Australia have been researching organic agriculture to varying degrees since the late 1980’s. This activity has ranged from international market investigation and development to research field trials on crop production issues. Information on organic research programs as well as technical notes for growers can be found on the departmental websites listed below.
NSW Agriculture Tel: (02) 6391 3100 Fax: (02) 6391 3336 email: [email protected] Internet: www.agric.nsw.gov.au. For the organic page, go to www.agric.nsw.gov.au/reader/485
Department of Primary Industries, Water and Environment, Tasmania Call Centre tel: 1300 368 550 Email: [email protected] Internet: http://www.dpiwe.tas.gov.au. For the organic page, go to ’Food and Agriculture’ then ’Organic Farming’
Department of Primary Industries, Victoria Call Centre Tel: 136 186 Email: [email protected] http://www.nre.vic.gov.au For the organic page, go to ’Farming & Agriculture’ then ’Farming Industries & Programs’ then ’Organic Agriculture’ (under farming Initiatives).
Department of Primary Industries, Queensland Call Centre Tel: (07) 3404 6999 Fax: (07) 3404 6900 Email: [email protected] Internet: www.dpi.qld.gov.au. For the organic page, go to www.dpi.qld.gov.au/business/660.html
Western Australia, South Australia and the Northern Territory don’t seem to have a particular focus on organic topics, but their websites still carry some useful information - you just have to search for it.
Primary Industries and Resources S.A. Internet: www.pir.sa.gov.au Department of Agriculture - Western Australia Internet: www.agric.wa.gov.au Primary Industry and Fisheries - Northern Territory Internet: www.dpif.nt.gov.au
References: Minou Yussefi and Helga Willer (Editors) (2003), The World of Organic Agriculture - Statistics and Future Prospects - 2003. Tholey-Theley: International Federation of Organic Agriculture Movements, 2003. ISBN 3-934055-22-2. Available from www.ifoam.org
OPEC, (2003). Terms Of Reference - Organic Produce Export Committee (OPEC), available at www.aqis.gov.au/organic
6 Soils Ain’t Dirt
Chris Alenson Soil farm consultant Macclesfield Vic.
“Can mankind regulate its affairs so that its chief possession - the fertility of the soil - is preserved? On the answer to this question the future of civilisation depends.” Sir Albert Howard, 1943
Introduction One of the guiding principles of sustainable/organic agriculture is the encouragement and maintenance of a healthy fertile soil. Almost every early proponent of sustainable or organic farming from Howard (1940), Balfour (1943), Sykes (1946) and King (1927), to more recent proponents such as Vogtman (1981), Woodward (1997) and Parr (1992), argue that the basis for successful sustainable farming is the building and maintenance of a soil high in fertility.
Soil management is not just about maximising the productive capacity of the soil but understanding the principle which implores us to consider the vital relationship that exists between the health of the soil and the plants and animals raised on this substrate.
The importance attached to this aspect of farming is illustrated by the statement by William Albrecht below:
“When more people learn that it requires fertile soils to grow protein rich, mineral rich, vitamin rich foods which mean good nutrition, we shall not need the half of the population to minister to the bad health of the other half”. William Albrecht
A Healthy Fertile Soil What is healthy fertile soil? A fertile soil in sustainable agriculture can be described as one which is capable of producing the vast array of nutrients, both organic and inorganic, to enable plants to develop to their fullest potential, both physically and nutritionally. This soil will have such characteristics as a good physical structure, adequate humus content and an abundant array of macro- and micro-organisms that assist in control of disease causing pathogens, the mobilisation of nutrients and maintenance of soil structure.
This fertile soil is more than just an anchoring point for the roots of a crop but a living ecosystem that performs a myriad of functions.
Principles of Sustainable Soil Management Just as there are guiding principles for sustainable/organic agriculture, so are there specific principles for the management of the soil.
Some of these are: • encouragement of biological life in the soil, • deep loosening, shallow turning when cultivation is utilised, • adherence to the ‘Law of Return’, ie. recycle all wastes, • organic matter/wastes to be returned to soil surface or shallowly incorporated, • a covering kept on the soil surface as often as possible.
The Living Soil A healthy fertile soil is not an inert medium in which to place crops but a complex mixture of minerals, organic matter, biological organisms, air and water in different proportions depending on their climatic and geological setting. All terrestrial life depends on this thin veneer of topsoil, roughly 50mm thick over the surface of our planet. The soil provides animals and man with food, and in turn, by recycling manure and plant wastes, the soil’s fertility is renewed. Continued growth of vegetation requires not only mineral elements for correct nutrition but biological activity to enhance this fertility.
The biological cycle of life, death and decay operate to restore the soil's health. Intervention by human kind through agricultural practices has broken this cycle, and soil degradation and fertility decline across the world has been the end result.
7 The value of a soil as a medium for plant growth depends not only on its nutritional characteristics but also on its physical structure. There are two aspects to the physical structure of the soil. Firstly the soil texture which is the particle size of the mineral matter and secondly the structure which is the arrangement of the mineral and organic components of the soil.
The mineral skeleton of the soil is formed from rock which has been broken down by either chemical, physical or biological weathering. Some soils (loess) are wind blown deposits carried from great distances, and other soils such as glacial soils might also have been deposited after being carried by glaciers and ice sheets. Not withstanding the methods of deposition, these fragments may be stone, gravel, sand, silt or clay. Sand and silt particles are roughly spherical while clays are plate-like. Clay particles are generally less than 2 micron in size and are termed colloids.
A soil with an ideal structure is one which contains large pore spaces to aid drainage, facilitate the movement of oxygen and carbon dioxide and the entry of plant roots, yet at the same time provides micro pores capable of retaining an adequate reserve of soil moisture for plant growth. The ideal structure will therefore consist of fine particles aggregated into water-stable crumbs. It is in the formation of these particles that organic matter plays such an important role. Intermediate products formed in the decay of organic residues are able to link clay particles together into the water-stable, clay-humus complexes called aggregates. These products of decay are subject to further break-down, however they are very important elements in the preservation of structure.
Their presence depends on: • inputs of fresh organic residues • microbial activity sufficient to initiate decay • adequate soil mixing to bring organic agents into close contact with the mineral particles.
The composition of an average silty loam by volume could be represented by the following pie diagram, with the organic matter including biota (living organisms). 75% of our surface soils have less than 1% organic carbon. Also shown is the structure of a soil aggregate (from Sattler, F. & Wistinghausen, E.V. (1992)).
Water film of water 25% structural element
medium-sized pore (holds water)
Mineral Matter large pore (holds air) 46% clay-humus colloids
colonies of organisms Air 25% Organic matter 4%
Grass and hay crops provide the basis for nurturing soil structure. The action of grass roots on the formation of soil aggregates should not be underestimated.
Good soil structure provides: • an environment suitable for the activity of micro-organisms and earthworms, • moisture, air and nutrients, • deep rooting medium for plants, • soil anchorage for plants.
8 The soil structure we are trying to achieve is found in the upper levels of the soil where there is the highest level of biological activity. Increasing the depth of this layer is a farmer’s aim in increasing soil fertility.
Organic matter in a soil is its life blood. Its content in a soil can vary from 1% (Australian average content) to 5% by volume. It may be the smallest percent of material present but it is of the utmost importance.
In the USA Yearbook, Soils and Men (1938) the following extract illustrates the importance given to organic matter:
“There is no true soil without organic matter. The high productivity of most virgin soils has always been associated with their high content of organic matter, and the decrease in the supply with cultivation has generally been paralleled by a corresponding decrease in productivity. Even though we can now feed plants on diets that produce excellent growth, without the use of any soil whatever, yet the decaying remains of preceding plant generations, redissolved by bacterial wrecking crews into simpler, varied nutrients for rebuilding into new generations, must still be the most effective basis for extensive crop production by farmers. Soil organic matter is one of our most important national resources; its unwise exploitation has been devastating and it must be given its proper place in any conservation policy as one of the major factors affecting the levels of crop production in the future.”
On decomposition, organic matter provides a well-balanced, slow release source of nutrients. It is composed of plant foods, carbohydrates (sugars, starch and cellulose), proteins and lignins, gums, resins, other organic compounds and mineral nutrients. Physically it helps maintain a balance between free-draining pores for aeration and small water-retentive pores. Humus, like clay, is a soil colloid and is involved in nutrient supply via exchange mechanisms. It has the ability to absorb trace elements such as copper and cadmium which might otherwise be toxic. It has a moderating influence on nutrient supply where elements might be either too low or too high.
Humus is not merely organic matter or the decaying remains of micro-organisms, but the end result of a living process where decaying organic matter is transformed by the action of soil organisms into a jelly-like substance with colloidal properties. The restoration of humus to the soil can improve the nutritional value of our crops.
Good soil husbandry will ensure that organic wastes are returned to the soil, pH is adjusted as required, the surface soil is protected against nature’s elements of wind and rain and an adequate oxygen supply to plant roots is maintained through judicious use of cultivation.
By returning wastes to the soil we are stimulating microbial activity and ensuring the population of soil organisms is maintained or increased. The vast majority of soil organisms, bacteria, fungi, actinomycetes, protozoa, algae and mycorrhiza are creators of fertility and are invaluable aids to the farmer.
Actinomycetes are thread-like organisms considered to exhibit behaviour in between bacteria and fungi. They are the second most prolific soil organisms and perform an essential role in breaking down organic matter into humus and other compounds. Some antibiotics such as streptomycin are also produced by them.
Fungi include molds, yeasts and mushrooms. They have filamentous (thread-like) structures called mycelium that form through the soil. They prefer aerobic conditions and can exist in acid soils. Fungi are one of the first organisms to dine on and decompose organic matter. The cell walls of fungi are made of chitin which is one of the most abundant nitrogen-bearing organic compounds found in nature.
Nodule-forming bacteria in association with legumes can fix up to 150kg of nitrogen per acre per year. This is the equivalent of 10-15cwt per acre of ammonium sulphate. If legumes do not appear to be nodulating effectively or fixing nitrogen then it is possible that the species of rhizobia is not present and inoculation may be required. It may be that the trace element molybdenum, essential for catalysing the process, is also not present. An over supply of nitrogen can inhibit the activity of rhizobia bacteria. Azotobacter are free-living nitrogen-fixing bacteria that also contribute greatly to the build-up of nitrogen in the soil.
Mycorrhizae are fungi-like threads that invade plant roots in a symbiotic relationship exchanging carbohydrates from the plant in return for supplying phosphate and trace elements to the plant. Mycorrhizal infection can more than double the root capacity of plants enabling them to source nutrients from a wider area, increasing their productive capacity while also apparently protecting them against some soil-borne pathogens.
9 Conditions which are favourable for the maintenance of an active biological soil population are air, water, food and warmth. Thoughtful management of this soil through careful cultivation, the return of organic residues and perhaps the occasional input of natural mineral nutrients will assist in maintaining and enhancing the fertility of the soil.
Larger soil organisms like earthworms, springtails, and in the Australian soil environment, termites and ants, provide valuable services of mixing soil with organic matter and aerating the soil.
Earthworms of course with their extensive tunnelling create passages for plant roots and moisture penetration into the soil. Their ingestion of soil and its subsequent expulsion as worm castes provides an enrichment process further mobilising soil elements.
The Living Soil and Disease Suppression As early as 1937 the microbiologist Waksman explained how disease-causing pathogens are destroyed by beneficial saprophytes. His experiments demonstrated that the pathogens did not survive long in good fertile soil. Baker and Cook (1988) state that the more varied and numerous the soil micro organisms, the greater the chance of biological control of the pathogen. Cook further stated that an organic rich soil, with good aggregation and hence good drainage and gas exchange is probably the most important factor in achieving and maintaining good root health for crops and stimulating biological control of plant pathogens.
Soil Assessment Understanding the soil, its needs, and its role in supporting healthy plants and animals is probably one of the most important areas that a farmer has to master. In the production of food and fibre whether it is for animal or humans the soil must be balanced in proteins, carbohydrates, vitamins and minerals to ensure optimum health and growth potential.
To achieve this desirable aim, a full range of the necessary nutrients must be available from the soil. The most comprehensive assessment we can make of the soil, and the ensuing cultural practices we use, will determine whether or not we lose the soil through erosion, lower its fertility, or in fact add value to both its physical and biological capabilities.
This diagram illustrates some of the factors involved in assessing on farm soil and farm health:
Physical Fertility Soil Determination - worms Analysis - texture
Plant Plant Analysis Assessment
Soil Nutrient - weeds Bank - grasses Animal or crop performance
Physical characteristics of a soil with good fertility
• good soil aggregation, both small and large particles, • as a result of good aggregation, pore spaces large and small should be evident, • dark colour indicative of higher levels of organic matter, • worms or numerous worm channels, • good water infiltration when poured on sample surface, 10 • absence of surface crusting, • good fibrous root penetration through depth of sample, • no compact layer impeding root progress, • nodules evident on legumes, • no root mat evident near surface, • no stagnant smell, • any other signs of soil life, dung beetles, ants, termites, • ease of insertion of metal spike or spade into the soil.
In Loius Bromfield’s book Malabar Farm (1949) a chapter titled ‘Grass the Great Healer’ gives a clue as to why well managed long-term pastures might provide good soil structure. The action of grass roots in developing soil structure should not be underestimated.
Soil Fertility Management The management of fertility on a farm will address organic matter levels and the supply of the inorganic elements if observation or analysis has indicated a need. Organic matter will be provided through the use of cover/green manure crops, incorporation of crop stubble, composts and other waste materials, and through the decomposition of roots of species grown in the rotation. Organic matter levels across most major Australian soil groups is 1% or less, so it is vitally important that these strategies are implemented.
The problem of managing these wastes and green manure crops is the management of the decay process. Poor handling of this material, such as burying it too deeply, can result in phyto-toxic residues that may damage following crops or tie up soil nitrogen, thus retarding the growth of the following crop. The choice of species for a green manure or cover crop will depend on the season of planting, the soil type, whether it is intended as a perennial cover crop or for ploughing in, and the purpose of the planting, i.e. building organic matter or supplying nitrogen. A permanent cover crop might be selected from white clover, strawberry clover or lucerne with an annual grass, while a non-permanent green manure crop might be selected from beans, peas, lupins, vetch, oats, barley or rye.
In horticultural production, the rotation should include, if possible, a soil-building phase of a legume and a green manure crop. Following the incorporation of compost or a green manure crop, it would be expected that there would be a significant increase both in the nitrogen supply and in the microbial population, benefiting plant nutrient availability and plant health.
The inorganic elements will be provided through a range of mineral fertilisers. In sustainable/organic systems, materials such as gypsum, dolomite, limestone, rock phosphate, rock dusts, and other minerals may be utilised.
Foliar sprays such as chelated compounds, seaweed, fish emulsion, biodynamic preparations and other biological preparations to supply trace elements and growth promoting substances are useful adjuncts to nutrient management.
Managing the Decay Process In sustainable agriculture, organic matter is usually either left on the surface or mixed into the surface soil. These materials will only decompose if certain species of fungi and bacteria, the "decomposers", are allowed to work on them. This recycling process forms large amounts of humus. The decay process not only manages crop residues, and supplies valuable plant nutrients, but also converts the food energy in fresh organic matter to a form that micro organisms can utilise.
Cultivation Cultivation in some circumstances can be an essential tool in assisting in soil fertility development. Through the opening up of the ground or breaking plough pans to allow the passage of water and plant roots, soil fertility is increased and soil structure is improved. The judicious use of cultivation to incorporate organic matter/stubble/green manure crops into the soil is an important part of managing the decay process. Ironically, cultivation is often seen more as a weed control tool rather than a technique to enhance soil fertility.
One of the key principles in sustainable/organic farming is ‘deep loosening, shallow turning’. This principle however is tempered by the understanding that many of our soils are fragile, and therefore minimal tillage is the expected practice to avoid destruction of soil structure through the breaking down of soil aggregates.
11 One of the agricultural pioneers in Australia, especially in relation to cultivation and water control on the farm, was P. A. Yeomans, whose book ‘Water for Every farm’ is one of the classics in Australian agriculture. His use of the chisel plough to facilitate this methodology is well known.
Nutrient and Energy Flows in the Soil Ecosystem In the soil ecosystem, recycling of nutrients utilises the energy generated through the photosynthetic process in plants. The main source of energy for the decomposers, ie bacteria and fungi, comes from crop and plant residues and to a lesser extent animal wastes. These wastes are broken down by the micro organisms to release the energy that the soil ecosystem requires to function.
Other than organic matter, the main source of nutrients in the soil comes from the soil minerals weathered free from the rock formations below. The activity of micro organisms and the organic acids and compounds released in this active biological system will assist in mobilising nutrient elements from these soil minerals.
Soil Fertility Decline It is important for an Australian farmer to realise that soil fertility on his/her property is affected by a number of factors. Fertility decline may be due to leaching of nutrients over geological time, the removal of soil through the erosional forces of wind and rain, depletion through cropping over many years without adequate return of organic and inorganic elements, poor management such as overstocking that may result in compacted soils, soils which have either too high or too low pH, or even poor irrigation practice leading to saline soils.
Summary Sustainable soil management is about fostering and enhancing a healthy, disease-suppressive soil capable of good production of quality produce. For this to be achieved, a good knowledge and understanding of the soil is required. Its principle components of biota, inorganic elements and oxygen are critical in arriving at this fertility goal. Stimulation of biological activity through the addition of organic materials, the provision of mineral elements and the management of soil gases through cultivation, crop rotation and general management will bring the farmer a step closer to achieving soils of ‘good heart’.
References Albrecht, W. (1975) The Albrecht Papers, Acres, USA. Alenson, C .J. (1997) Soil Fertility/Soil Quality Monitoring, Organic Farmer. Arshad, M.A. and Coen, G.M. (1992) Characterisation of soil quality: Physical and chemical criteria, American Journal of Alternative Agriculture, vol. 7. Nos. 1&2. Balfour, E.B. (1975) The Living Soil & The Haughley Experiment, Faber & Faber, London. Carter, R, (1993) Broad Acre Cereal Farming, Organic Farmer, Summer. Cook, R .J. (1984) Root Health: Importance and Relationship to Farming Practices. Fawcett, R.G. et al (1990) The role of rotations and conservation tillage systems in sustaining crop production and soil resources. Howard, Sir, A. (1945) An Agricultural Testament, Oxford University Press, London. King, F. H. (1927) Farmers of Forty Centuries, Reprinted by Rodale Press, Emmaus, Pennsylvania, USA. Parr, J.F. et al (1992) Soil Quality: Attributes and relationship to alternative and sustainable agriculture, American Journal of Alternative Agriculture, vol. 7. Nos. 1&2. Pfieffer, E. (1983), Soil Fertility-Renewal & Preservation, Lanthorn Press, Peredur, East Grimstead, Sussex, England. Reganold, et al, (1993) Soil Quality and Financial Performance of Biodynamic and Conventional Farms in New Zealand. Sattler, F. & Wistinghausen, E.V. (1992) Bio-dynamic Farming Practice, Cambridge University Press Cambridge, UK. Schrieffer, D.L. (1984) From the Soil Up, Wallace-Homestead Printing Co. Des Moines, Iowa, USA. Sykes, Friend (1946) Humus and The Farmer, Faber & Faber, London. Tisdall, J.M. et al (1978) The Stability of Soil Aggregates as Affected by Organic Materials, Microbial Activity and Physical Disruption, Aust. J. of Soil Research, vol. 16. Tisdall, J. (1989) Earthworms - Their Importance and Encouragement in Agriculture, in the Collected Readings. Yeomans, P.A. (1978) Water for Every Farm, Murray Books, Ultimo, New South Wales. Yeomans, A.J. (1990) The New Challenge of Agriculture, Eco Ag 90 Conference , Melbourne, April.
12 Microbial Biomass: What’s Eating YOUR Organic Matter?
Dr. Darryl Nelson Research Scientist DPI, Rutherglen Research Institute, Rutherglen
DE PAR T ME NT OF PRIMARY INDUSTRIES
The Bold and the Beautiful: Microorganisms in Organics Darryl Nelson DPI Rutherglen
11/07/2003
DE PAR T ME NT OF PRIMARY INDUSTRIES Overview
• Ecology of soil microorganisms: who’s there?
• Function of soil microorganisms: what are they doing?
• Microbes in organic soils: are they happy?
• How to manipulate the soil microbiology
• Summary
2
13 DE PAR T ME NT OF PRIMARY INDUSTRIES Ecology of Soil Microorganisms
• Soil contains millions of microorganisms per gram
• Most numerous are bacteria and fungi (up to 90% biological activity)
• Delicate balance governed by temperature, moisture, oxygen, nutrient availability
• The soil is a battleground - a constant fight for available nutrients
• R strategists - THE BOLD: organisms rely on high reproductive rates for continued survival within the community - populations subject to extreme fluctuations (pathogens)
• K strategists - THE BEAUTIFUL: organisms depend on physiological adaptations to environmental resources - usually stable and permanent members of the community
3
DE PAR T ME NT OF PRIMARY INDUST RIES Ecology: Dirty Tricks
• Microorganisms will do many things to get an advantage on others
• Fungi produce mycelia which seek out nutrients, mycorrhizae
• Antibiotic production (fungi, actinomycetes)
• Faster growth rates, temperature optima
• nutrient solubilisation (Phosphorus)
• Sporulation
4
DE PAR T ME NT OF PRIMARY INDUST RIES E col ogy of S oil Micr oor ganis ms
BIOLOGICAL Rhizobacteria and Fungi: Beneficial (N and P) and Detrimental (disease)
ROOT CHEMICAL TOXIC ELEMENTS VAM Boron, Aluminium, etc.
CHEMICAL ROOT EXUDATES Sugars, organic acids, etc.
BULK SOIL
PHYSICAL RHIZOSPHERE Compaction Waterlogging
5
14 DE PAR T ME NT OF PRIMARY INDUST RIES Functions of soil microorganisms
• Diverse range of functions in soil
• Degradation of organic compounds (plant material, pesticides)
• Transformation of N, P and other nutrients
• Enzymes
• Important to maintain functional diversity in soils - resilient populations
• N Fixation, nitrification
6
DE PAR T ME NT OF PRIMARY INDUSTRIES The Carbon Cycle
7 Modified from Rowell (1994)
DE PAR T ME NT OF PRIMARY INDUSTRIES The Nitrogen Cycle
8 Modified from Rowell (1994)
15 DE PAR T ME NT OF PRIMARY INDUSTRIES Organic Soils - are they happy?
• PROBABLY!
• Increases in organic matter > higher microbial activity (not diversity!)
• OM is often complex in nature thus often selects for K strategists
• Suppressive soil: high OM and microbes - prevents more aggressive disease-causing microorganisms
• Essential part of organic farming due to nutrient turnover capabilities in the absence of soluble fertilisers
• Changes in microbial communities often subtle and not detected by regular biomass determination (Shannon et.al, 2002)
9
DE PAR T ME NT OF PRIMARY INDUSTRIES Community Analysis of Two Soils
• “Citrus” - an organic soil in place for some time • “Vegetable” - a new organic soil with constraints (eg. N)
• The soils were analysed for their community structure using the Biolog® system
10
DE PAR T ME NT OF PRIMARY INDUST RIES Community Analysis of Two Soils
Soil Response 56% increase in utilisation 0.9 0.8 0.7 0.6 0.5 Citrus 0.4 Vegetable 0.3 0.2 Absorbance (595nm) Absorbance 0.1 0.0 Treatment
• Significant difference in microbial response • 11/31 Carbon sources significantly different • Diversity was slightly higher in Citrus soil but not significant 11
16 DE PAR T ME NT OF PRIMARY INDUSTRIES Organics - manipulating microbes
• Microbes respond to temperature, moisture, physical changes and nutrient availability
• OM correlated to microbial biomass
• Any practice which increases OM may be beneficial
12
DE PAR T ME NT OF PRIMARY INDUST RIES Organics - manipulating microbes
• Literature is mixed in regards to how effective organic farming is in increasing biomass
• Composting - bacteria, actinomycetes and fungi higher in organic plots with compost (80-120 t/ha) (Sivapalan et.al., 1993)
• Green manure and tillage practices - higher enzymes and biomass (Reganold, 1988)
• Legumes and grasses in rotation / composted manure - higher saprophytic (wood degrading) fungi (Elmholt and Kjoller, 1989)
• Reducing tillage - increased biomass (Gupta and Roper, 1994)
13
DE PAR T ME NT OF PRIMARY INDUST RIES Organics - manipulating microbes
• Organic tomatoes - increased actinomycete levels and suppression of corky root disease (Workneh and van Bruggen, 1994)
• Pathogenic fungi (eg Rhizoctonia solani) were absent in organic plots compared to conventional; antagonistic fungi were in higher numbers in organic plots with >80 t/ha composted manure, brown coal and grass (Sivapalan et.al, 1993)
• Vesicular-Arbuscular Mycorrhizae (VAM) - soil structure and antagonism - preceding crops can influence amount of VAMs
14
17 DE PAR T ME NT OF PRIMARY INDUST RIES VAMs
Source: Ryan (2001)
Source: Kabir and Koide (2000) 15
DE PAR T ME NT OF PRIMARY INDUST RIES Problems Manipulating Soil Microbiology
• Can take many years to increase OM / biomass levels
• Older OM (> 30 yr) influences biomass more readily than newly applied OM, which does not persist (Witter et.al., 1993)
• OM levels - 6 years of radically different treatments (organic, conventional etc) did not change levels, but higher levels of microbes in organic / biodynamic plots (Penfold et.al, 1995)
• After 30 years organic treatment (rock P), no difference in yield, higher in conventional system in one year (Dann et.al., 1996)
• Community structure may be related more to particle sizes of soils and less to external factors (Sessitsch et.al, 2001)
16
DE PAR T ME NT OF PRIMARY INDUST RIES How can you increase OM?
• Protecting the soil surface - retains moisture and limits large temperature fluctuations
• Green manure crops
• Manure and composting
• Retain stubble
• Longer pasture phases and minimising tillage
17
18 DE PAR T ME NT OF PRIMARY INDUST RIES How can you increase OM?
IT MAY TAKE A LONG TIME TO CHANGE YOUR ORGANIC MATTER CONTENT!
18
DE PAR T ME NT OF PRIMARY INDUST RIES Summary
• Microbiology is of great importance in organic farming - they take the place of chemical applications
• Temperature, moisture, nutrients and aeration are crucial to an active biomass
• Favour your K strategists!
• It may take a long time to change organic matter content, hence microbial biomass
THANKS!
19
19 Organic Vegetable Research at the Sunraysia Horticultural Centre
Christiane Jaeger Research Officer DPI, Sunraysia Horticultural Centre, Irymple
Overview Between 2000 and 2003, the Victorian Government funded as part of the Naturally Victorian Initiative, the project Sustainable Organic Production Systems (SOPS). The organic vegetable component of the SOPS project has been undertaken at the Sunraysia Horticultural Centre (SHC). Its objectives is to: • establish an organic production research site for the collection and publication of scientific data on production, pest and weed management, soil and plant nutrition, and marketability of product. • develop new strategies for weed and pest management that are applicable to both conventional and organic production systems. • investigate organic carrot production, as this crop had been identified as having export market potential.
A 0.8 ha vacant block was available on site at SHC, Irymple, for development to an organically certified research site. In October 2002 the site obtained pre-conversion status. The first steps taken to develop the site were: • a visual assessment of the block, its dimensions, contours, weeds and border vegetation; • design and establishment of a new irrigation system with a distribution uniformity of 80 - 85%; • a soil pit for a soil profile analysis; • analysis of soil samples for nutrients, pH, salinity, organic matter, and micro-organisms; • a descriptive report that combined all findings as a basis for decisions about how to manage the block and a benchmark to evaluate possible changes.
Organic vegetable research activities at SHC A survey of organic vegetable growers was undertaken to learn about growing practices and issues of concern within the industry. Clear research propositions emerged from the survey, which aligned with the project and site requirements. These were effective and efficient weed control and knowledge about benefits and types of green manures.
1. Weed control trials Prevalent weeds growing on the site were Caltrop, Gentle Annie and other annual grasses, Wild Turnip, Fathen, Capeweed, 3-Corner Jack, Black Nightshade, Couch grass and Nutgrass.
Post-emergence weed suppression in green manures Maintenance of soil health requires the inclusion of a green manure phase in the crop rotation. Control of weeds is but one of the benefits. Post-emergence mechanical weeding enhances the weed suppressing effects of the green manure.
An implement that is hardly known in Australia, but much used in Europe, is the comb harrow. Other names for it are flexi-tine harrow or Striegel. This implement is constructed of flexible, spring loaded 5mm diameter round rods on a flexible frame. It is soft on soil structure, and working depth can be varied according to weed growth. The implement works best, when the weeds are not larger than the 4 – 6 leaf stage. The weed suppression achieved with this implement in a summer green manure crop trial is shown in Table 1. This table shows that the first Striegel cultivation reduced the weeds per m² considerably. At the following counts, new weeds had emerged. However, these new seedlings remained small, light green and weak due to the competition from the green manure crop. Table 1: Weed count in summer green manure crops before and after cultivation with a Striegel for weed suppression. Striegel cultivations occurred on 14/12/01 and on 09/01/02 Weed counts per m² Green manure and sowing rate Before After cultivation 6/12/01 12/12/01 27/12/01 17/01/02 11/02/02 Cowpea @ 25kg/ha 2.3 5.2 2.8 1.2 5.3 Cowpea @ 50kg/ha 0.9 4.7 3.9 2.4 3.1 Millet @ 25 kg/ha 3.1 3.2 1.6 2.4 2.8 Millet @ 50 kg/ha 2.9 2.2 0.4 0.0 0.3 Cowpea @ 25 kg/ha + Millet @ 25 kg/ha mixture 1.5 4.3 1.7 2.1 1.6 Cowpea @ 40 kg/ha + Millet @ 40 kg/ha mixture 1.0 2.5 1.2 0.5 1.2
20 Weed control in carrots In carrots, effective weed control was trialed with 3 different implements: • goosefoot tine harrow; • comb harrow; • rotary-tine cultivator (Weed-fix );
Table 2 shows the results of the weed control trial with these implements.
Table 2: Percentage reduction in numbers of carrot seedlings and weeds by three different weeding implements (Mildura 2002) Goosefoot tine cultivator Comb harrow Weed-fix Carrots Weeds Carrots Weeds Carrots Weeds 67% 83% 33% 82% 0% 80%
The Weed-fix had the least impact on the carrot seedlings. Further details of the implements and the trial are described in the Agnote Organic farming: Weed control in organic carrots – Implements. at http://www.nre.vic.gov.au/notes/, then click on General Farming, then Organic Farming.
Weed control between the sprinklers of a fixed sprinkler system Methods trialed were: • hand weeding; • pine oil spraying; • flaming with a handheld gas bottle; • straw mulch; • black weedmat, with straw to prevent the weedmat from blowing away; • planting of Myoporum parvifolium, Creeping Boobialla, a native groundcover, which was used as a living weed-suppressing mulch.
Results: Both, pine oil and flaming, were effective only on small weeds and had to be applied frequently. The treatments were discontinued due to the expense of the pine oil and the time consuming and cumbersome operation of the manual flaming.
Straw was effective when laid to a minimum of 5 cm thickness. Weedmat and straw together controlled weeds better. However, weeds grew out at the sides of the mulches. A further disadvantage was that strong winds and implements catching on the straw or weedmat tended to shift the mulch and thus create opportunities for weeds to emerge in the exposed areas.
The Myoporum sp. appeared to be the most promising weed control method in the long term, although it did not completely suppress Couch grass and Nutgrass. A disadvantage is the need for coulters to cut off shoots that grow into the vegetable beds. A great advantage of the Myoporum sp. as a native plant is that its planting contributes to the organic standards requirement (from 1st June 2005 onwards) of a minimum of five percent of organic farm area to be covered by native vegetation.
Insects were collected from the Myoporum sp. in November 2002 for an indication of whether the native groundcover would function as habitat for pest and/or beneficial insects. The species found are shown in table 3.
Table 3: Numbers of beneficial and pest insects found in Myoporum parvilfolium Beneficial/Predator/Parasitoids Numbers Pest Numbers Anthicidae (beetle predator) 2 Agromyzid (leafminer) 1 Geocoridae bug 1 Creontiades dilutus (Green mirid) 3 Hippodamia variegata, (aphid predator) 1 Leaf hopper 8 Ladybird 2 Rutherglen bug 9 Native bee 4 Sidnia kinberg (Crop mirid) 15 Metaphycus parasitoid 1 Parasitoid Scrutellista 1 Parasitoid wasps 39 Spider 1 Other insects, mainly flies 30
21 Suppression of Nutgrass and Couch grass This trial commenced in January 2003 and is still ongoing. The objective is to suppress the very densely growing Couch grass and Nutgrass on the headland, as they were a source of invasion for the vegetable beds. The preferred option, letting pigs root the weeds out, was not feasible to implement. Hence the option of frequent flaming with the aim of exhausting the plants’ reserves was chosen. A 3-point-linkage flame weeder being unavailable, and a manual flaming torch was used.
Half of the headland was initially disced and the other half slashed. In January, February and at the beginning of March, flaming was performed every second day. By the end of February, the Nutgrass on the originally disced section of the headland had regrown so densely that it was necessary to rotary hoe the area very shallowly to 1—2 cm depth. In a following pass, the Till-fix implement, a vibrating cutting bar on the 3-point linkage of the tractor, lifted many Nutgrass bulbs to the surface for desiccation.
Results: The vigour of Nutgrass and Couch grass on the headland was reduced by flaming. Flaming had to be carried out every second day in summer, due to the vigour of the Nutgrass growing 1-2 cm per day. The Couch grass regrew much more slowly than the Nutgrass; it would have been sufficient to flame only every fourth to fifth day. From mid-March onwards the regrowth of the weeds slowed down so that flaming needed to be done only twice per week and at the end of April, only once per week.
A visual assessment after the cultivation in February gave the impression that regrowth of the Nutgrass was much thinner. In April, regrowth leaves of Nutgrass were light green and narrower, an indication that the nutrient reserves in the bulbs were becoming exhausted.
Gas expense between 23 January and 30 April 2003 was $260 for an area treated of 0.03ha (330 m²). A 3-point- linkage flame weeder could be expected to be more efficient and economical due to being more accurate in the flaming compared to a manual operation. But unfortunately, this could not be trialed.
2. Green manure trials In view of the poor soil condition of the demonstration site and insufficient knowledge among growers about green manures, it was decided to grow a green manure crop before planting vegetables. Two summer green manure crops were chosen and planted at different seeding rates, as monocultures and mixtures. These crops were millet, (a cereal), and cowpea, (a legume). The mixture was incorporated into the trial for reasons of combining the benefits of both green manures, e.g. nitrogen fixation by the legume with better early weed suppression by the fast growing grass, and increased diversity in the soil microbial community from greater plant diversity.
Table 1 reveals that the high seeding rates of millet and millet & cowpea mix gave the best weed control results. However, in regards to adding dry organic matter to the soil, the lower seeding rates produced more dry matter above ground and millet produced more dry matter than cowpea (Table 4).
Table 4: Above ground dry matter production of the summer green manure crop Total weight dry Green manures and seeding rates matter t/ha Cowpea @ 25kg/ha 4.0 Cowpea @ 50kg/ha 3.9 Millet @ 25 kg/ha 7.3 Millet @ 50 kg/ha 6.7 Cowpea @ 25 kg/ha + Millet @ 25 kg/ha mixture 6.3 Cowpea @ 40 kg/ha + Millet @ 40 kg/ha mixture 6.0
The summer green manure crops in 2001/2002 were grown on the whole vegetable block. To enable the implementation of crop rotations while fulfilling the project’s requirement to grow carrots, it was necessary to divide the site into three equally sized sub-blocks, B1, B2, B3. In winter 2002 carrots (B1), spinach(B2), and a winter green manure crop of ryecorn and hairy vetch mix (B3) were planted. A 3½ months long fallow from spring to early summer followed the winter crops. Carrots (B3), and summer green manure crops of yellow mustard, sorghum and cowpea (B1 & B2) were planted after the fallow at the end of January 2003.
Soil samples were not taken after incorporation of the summer green manure in 2002 due to budget constraints and the expectation that the organic matter and micro-organism biomass content increases immediately after 22 incorporation for the short term. However, samples were collected and analysed in January 2003 after the spring/summer fallow, because we were interested to investigate, if there were any long term residual effects of the green manure.
Results:
Table 5 presents the results of the soil pH, organic matter, major nutrients, cation exchange capacity and microorganisms of the two soil analyses in January 2001 and January 2003.
Table 5: Soil analysis results of organic matter, major nutrients and microorganisms Analysed items B1 B2 B3 2001 2003 % Diff. 2001 2003 % Diff. 2001 2003 % Diff. pH 8.2 8.3 1.2 8.2 8.6 4.9 8.6 8.7 1.2 available calcium ppm 1352 1948 44.1 1614 1854 14.9 1710 2930 65.5 avail. magnesium ppm 128.4 158.4 23.4 131.4 144 9.6 126.6 165.6 30.8 available sodium ppm 23 50.6 120.0 23 57.5 106.5 17.3 39.1 126.0 available nitrogen ppm 9.4 6.8 -28.9 6 5.4 -10.0 5 4.7 -6.0 avail. phosphorus ppm 34.3 39.7 15.8 12.9 44.6 245.7 21.5 27.5 27.9 avail. potassium ppm 224.5 265.2 18.1 179.4 370.5 106.5 181.4 315.9 74.1 available sulphur ppm 1.3 3.7 184.6 2.6 4.1 57.7 0.6 3.7 483.3 total organic matter % 1.2 0.8 -33.3 0.7 0.8 14.3 0.5 0.5 0.0 cation exchange capacity 7.6 10.7 40.8 8.7 10.4 19.5 9.2 15.9 72.8 bacterial biomass µg/g 161 22.6 -86.0 190.5 37.9 -80.3 132 47.8 -63.8 fungal biomass µg/g 25.5 30.1 18.0 36 21.2 -41.1 29.5 22 -25.4 protozoa numbers no/g 21614 1231 -94.3 22258 5498 -75.3 414 11256 2618.8 nematode numbers no/g 0.5 1.7 240.0 0.8 2.6 225.0 0.3 3.4 366.7
In summary, the figures show that • the sub-blocks vary in level and change of organic matter, nutrients and microorganisms possibly due to their differing crop production histories; • the green manure activated soil life, which led to a mobilisation of soil nutrients. However, after 3½ months fallow, the added organic matter was decomposed and microbial biomass declined, especially in the sub-blocks where poor vegetable crops preceded the fallow. This highlights the fact that a green manure crop followed by fallowing will not increase soil organic matter in the long term.
Further information
1. The implements trialed The comb/flexi-tine harrow/Striegel is made by the companies Hatzenbichler, Austria, and Lely (http://www.ecoweb.dk/english/ifoam/conf96/abs193.htm). Lely Australia does not stock this harrow. The Hatzenbichler Striegel is distributed by Fix Engineering in Musk, via Daylesford; ph: 03-5348 2669; email: [email protected]
The Weed-fix and Till-fix are implements made by Fix Engineering.
Please, note that neither the author nor DPI endorse the implements trialed as the best or only ones to be used for mechanical weed control.
2. Note Series Agnote Organic farming: Weed control in organic carrots – Implements. at http://www.nre.vic.gov.au/notes/, then click on General Farming, then Organic Farming.
23 DPI Program to Test Certified Organic and Biodynamic Produce for Potential Contamination
Ruth McGowan State Coordinator, Horticultural Residue Management DPI Ellinbank
From August 2002 - April 2003, the Department of Primary Industries (DPI) has been conducting a comprehensive, residue monitoring program which will test certified organic and biodynamic produce for potential contamination from a range of synthetic chemicals and heavy metals.
Project Aims • Enhance the clean reputation of Victoria’s organic and bio-dynamic industries by undertaking a rigorous scientific study of certified produce to help validate claims that the produce is clean. • Assist certifying organisations and DPI to identify and assess risks of potential contamination from current or past farm chemical use in conventional systems. • Complement DPI’s Organic Industry Strategy, which aims to expand Victoria's organic exports.
Who is behind this project? DPI is working with the Organic Federation of Australia (OFA) and key member organisations to conduct this program. Throughout early 2002, DPI’s State Coordinator for Horticultural Residue Management, Ruth McGowan contacted various certification organisations to discuss plans for this chemical residue monitoring project. Organisations contacted included the Organic Federation of Australia and the four main certifying organisations covering Victorian growers, (National Association for Sustainable Agriculture Australia, Biological Farmers Association, Organic Herb Growers Association, and Bio-Dynamic Research Institute). AQIS and RIRDC also provided advice and input.
This project is funded under the Victorian Government’s Naturally Victorian Initiative with in-kind support provided from OFA and certifying organisations.
Sampling Approximately 300 samples will be taken from retail outlets throughout Victoria and tested for residues of chemicals and heavy metals. Most of the samples will be sourced from the Melbourne Market in Footscray and will include 100 samples of fruit and nuts; 100 samples of vegetables and herbs and 100 samples of various field crops. The sampling program is approximately in proportion to current export of organic and bio-dynamic produce from Victoria. All samples will be taken from Victorian growers who have certified to NASAA, BFA, OHGA or BDRI standards.
Samples of approximately 1 kg each (including at least 10 units of produce) will be randomly taken each week by DPI Plant Standards staff from wholesale and retail outlets in Melbourne and sent to the Victorian State Chemistry Laboratory. Although costly to test such a large number of samples, 300 is the internationally recognised number required for random monitoring programs of this type in order to provide the appropriate degree of statistical confidence.
Testing At the laboratory, samples will be tested for potential contamination from farm chemicals, which may be currently used (or are now banned but may have been used in the past) by conventional farming systems. These include organophosphates, organochlorides and synthetic pyrethoids. Samples will also be tested for heavy metals, which can be naturally high in some soil types or occur as a result of previous farm practices. Testing is being done at DPI’s State Chemistry Laboratory which is accredited by the National Association of Testing Authorities for these type of tests. 1. This laboratory can detect chemicals down to one part per billion, the equivalent of half a teaspoon of water in an Olympic-sized swimming pool.
Reporting Once analysis has been completed (usually about three weeks after samples have been received), the test results will be compared with domestic and export standards for contaminants, as well as standards set by individual
1 Chemicals to be tested for include: Azinphos-Ethyl, Azinphos-Methyl, Chlorpyrifos, Chlorpyrifos-Methyl, Diazinon, Dichlorvos, Dimethoate, Ethion, Fenchlorphos, Fenitrothion, Fenthion, Malathion, Mevinphos, Parathion-Ethyl and Parathion-Methyl, Alph-BHC, beta-BHC, delta-BHC, Hexachlorobenzene, Aldrin, Lindane, Heptachlor, Heptachlor Epoxide, Dieldrin, DDE, DDD, DDT, alph-Endosulfan, beta-Endosulfan, Endosulfan-sulphate, Endrin, oxy/cis/trans- Chlordane, Cyfluthrin, Cyhlothrin, Cypermethrin, Deltamethrin, Fenvalerate, Flumethrin and Permethrin, Iprodione, Carbaryl, Methomyl, Atrazine, Simazine and Hexazinone and the Heavy Metals: Copper, chromium, cadmium, lead. 24 certification organisations. Results will then be conveyed to the relevant certification organisation and will remain confidential to the individual organisations and DPI.
If a result is recorded at above the Maximum Residue Limits (MRLs) for residues in conventional produce (set Nationally by Food Standards Australia and New Zealand, FSANZ) this will be deemed to be unacceptable by DPI. An Authorised Officer from DPI will conduct a trace-back to the farm of origin in conjunction with the certifying organisation, to try and determine the cause of the residue. If a result is below the FSANZ MRL, it will be at the discretion of the certifying organisation as to what action needs to be taken to determine the cause of the residue. Certifying organisations will also independently determine how individual analytical reports and test results will be communicated to growers.
Results of the testing program will be summarised and publicised through the organic press from June 2003 and at the OFA conference (October 2003).
Results to date As of April 2003, all samples have been taken, and 200 of the 300 samples have been analysed. So far, so good, as there have been no violations of the FSANZ standards. Two samples have recorded very low levels of pesticides, apparently through environmental contamination. Several samples have recorded relatively high levels of cadmium and this is being addressed by the relevant certification organisation.
Why is this testing being conducted? While the testing is not expected to show significant detections, this program is undertaken in the knowledge that organic or bio-dynamic certification systems in themselves, cannot always ensure that produce is completely free of residues of agricultural chemicals and other contaminants. There are risks that contamination or pollution can occur beyond the control of the producer through air, water, soil or other sources. Residue monitoring is an accurate way of identifying where these risks are so that they can subsequently be managed.
As a result of concerns about genetically modified organisms, foot and mouth and ‘mad cow’ disease and other food scares, consumers here and overseas are increasingly worried about the potential contamination of our food supply. As a result, many shoppers are turning to organic produce in the belief that produce marketed this way has no pesticide residues. While certifying organisations in Australia do not claim this feature as a quality of organic produce (due to the recognised potential for contamination), produce is often marketed as being ‘pesticide free’ and this belief remains a common perception of shoppers. While such an attribute can mean that organic and bio- dynamic produce has a competitive advantage over conventional produce, it also means that this industry is vulnerable to food scares, which could damage the ‘clean and green’ reputation of produce. In future, the provision of the data generated through this DPI project could be used to refute such allegations and to demonstrate that produce is clean.
A study by the United States Department of Agriculture in 2002 found that produce testing in the USA was detecting 1/3rd fewer chemicals on organic produce, and the residues were at lower levels than on conventional produce.
What about conventionally grown produce? DPI has considerable experience in running residue-monitoring programs and this is a key tool in our risk management approach to chemical use. Since 1987, DPI has conducted the annual Victorian Produce Monitoring Program which targets fresh produce and tests for a range of chemicals in order to assess the extent of contamination in conventional horticultural production. About two thirds of samples tested under DPI’s targeted programs contain no residues and usually 3% may contain unacceptable residues which breach the FSANZ MRLs. Statistically valid (random) testing programs have also recently been conducted on asparagus, citrus and nectarines in Victoria.
Who do I contact for more information? Project Manager, Ms Ruth McGowan State Coordinator, Horticultural Residue Management Post: DPI Ellinbank, RMB 2460 Hazeldean Road, Ellinbank, 3818 Ph 03 56 24 2202, Fx 03 56 24 2200 Email: [email protected]
25 Soil management field day - Sunraysia Horticultural Centre - April 30, 2003 Some grower perspectives on organic production and soil management
Sue Dickinson, Vinifera Vegetables (mainly carrots) and table grapes
• Property size 27Ha plus another 16Ha leased. • Converted to organic management in 1993. • Weed management in vegetable crops is by flame, mechanical cultivation and hand weeding. • Humic coal is banded along carrot rows to build soil organic matter and improve the moisture-holding capacity. • Commercial compost tea is applied to the soil at carrot sowing time to boost soil microbial activity. • Kelp is applied to carrots during the season as a foliar spray to improve plant health. • Guano is used as a phosphorous source. Blood and bone is also used, with zinc added when a need is indicated by soil tests. • Yellow mustard is grown in rotation with carrots as a biofumigant against nematodes. It is also a useful green manure crop. • Vines and carrots are tested yearly for nutrient status by leaf analysis. • Vineyard mid-rows are sown to winter green manure crops (ryecorn, beans, peas, snail medic) and are mulched and bladed in early summer for flood irrigation.
Andrew Jones, Irymple Grapes, citrus and avocados
• Property size 22Ha, wine, dried and table grapes, citrus and avocados. • Converted to organic management in 1989 - had been virtually organic since the 1970’s. • Young vines are cultivated to keep weed-free to minimise competition • Green manures (eg faba beans, oats) and cover crops (eg white clover) have been used to suppress weeds. Cover crop and weed growth is managed by slashing. • Aged poultry manure is applied to mature vines after harvest - spread onto weed/cover crop growth then cultivated in as preparation for sowing a winter green manure crop. • Commercial organic fertilisers are applied by hand to new vines. • Fish emulsion is applied to vines as a foliar spray prior to flowering. • Used to produce on-farm compost but stopped due to high soil potassium levels resulting from high potassium levels in the grape marc used. • Compost was based on poultry manure, grape marc and straw. • Furrow-irrigated blocks are deep ripped prior to sowing green manure crops, to break up any hard pan.
26 Robert Ridgwell, Palinyewah Citrus, avocados and plums
• Property size 21Ha (17 Ha citrus, 1 Ha plums, 2 Ha avocados). • Conversion to organic management began in 1989. • Soil/crop nutrition has based on farm-produced compost since 1994, partly because of the high cost of commercial organic nutrient sources. • The use of commercially composted green municipal waste is now being considered for part or full replacement of the on-farm composting because of the cost involved in ’doing it right’. • The on-farm compost is currently based on poultry manure, redgum sawdust, grape marc, brown coal and forage-harvested green matter from the property. • The intention is to replace brown coal with sawdust and farm-grown green plant material (coal is expensive and the feeling is that fresh organic matter will be more beneficial). • Some plant material for composting is harvested after it has matured, to add some harder woody material to the compost mix. • Compost is applied in split applications which are timed in an effort to maximise the benefit to soil microbes, eg when environmental conditions are most favourable for microbe activity. This depends on temperature and moisture. • Application of compost is concentrated under the drip line of the trees to focus the benefit there. • Composting is not a simple process and it has been increasingly monitored and managed to greater detail to improve the quality and suitability of the final product for the property’s requirements. • Monitoring of compost includes testing for its microbial composition. • Similar microbial testing is also being applied to the soil as part of a strategy to anticipate soil-based problems and rectify them before they develop too far. • Some of the soil is high in magnesium and potassium - care with the composition of compost is required to avoid excess soil levels of these elements. • Compost teas are being used and further investigated for enhancement of soil microbial populations. • Foliar applications of trace elements (copper, zinc, boron, manganese, molybdenum) are used when necessary, as indicated by visual deficiency symptoms in foliage and leaf analysis results. • Apart from copper, trace elements will be applied more as a component of compost teas for soil and foliar application. • The approach to soil care includes minimal soil disturbance (eg for weed control) and avoidance of traffic on wet soil, to minimise soil compaction. • Slashing and side mowers are used to cut weeds in mature plantings, and shallow knifing is used to minimise weed growth in young plantings where competition with smaller trees is a more critical issue.
27 Which Green Manure Should I Grow?
Christiane Jaeger Research Officer DPI, Sunraysia Horticultural Centre, Irymple
The Department of Primary Industries, Victoria (DPI) publishes an agricultural Notes Series called Agnotes. The Notes Series is accessible on the internet. Open the web page http://www.nre.vic.gov.au, then click ‘Farming and Agriculture’, then ‘Specialised Industries’, then ‘Organic Agriculture’, then “Organic Agriculture – Information Notes’, then the desired Agnote. This handout should be read in conjunction with the Agnote Organic farming: Green manures for vegetable cropping (AG 1084).
Introduction Agnote 1084 describes, in general, the benefits of growing a green manure crop, some matters to consider when choosing the crop and how to manage it. Which Green Manure Should I Grow collates in more detail, important characteristics of many green manure crops that can be grown in Victoria. Knowing these characteristics will help growers to choose the green manure crop that best fits into the crop rotation, suits the site specific conditions and farm plan goals.
Explanations and comments to the column headings of the attached green manures list General points • Blank fields in the list mean that information was not available at the time of writing about characteristics pertaining to a column heading. This may not mean, however, that the crop does not have that characteristic. For example, Arrowleaf clover has a blank field in the column Host/habitat for beneficial insects, because no specific mention was found in the literature about Arrowleaf clover providing a habitat for beneficial insects. However, it can be expected that the general statement about clovers in that column also applies to this particular clover species. • Space was a limiting factor to listing everything that is known about each crop. The emphasis is on important features that are not as readily accessible as, for example, required temperature range at which the crop grows best, soil pH, soil type, Rhizobium inoculant group, growing season, and minimum growth period. It is important to seek information about these latter characteristics when choosing any green manure crop. These features are usually known by the local seed merchants.
Green manure/Cover crop This column contains the common names of crops that are either used as a green manure crop or as a cover crop. A green manure crop is a crop that will be incorporated into the topsoil for decomposition, soil improvement and nutrient release before the planting of a cash crop. A cover crop, in comparison, is planted to provide soil cover and improve the soil through its root system. It may or may not be incorporated into the soil at the end of its life. Perennial cover crops are left standing for several years until they lose vigour, while some annuals, for example medics, are left to ‘hay off’, that is, left to go to seed in early summer and to naturally regerminate the following autumn. Hence, most crops can be used either as a green manure or as a cover crop, although they are usually more suitable for one or other purpose. The green manure/cover crops in this list are grouped into ‘legumes’, ‘other broadleaf crops’, and ‘grasses’.
Botanical name Sometimes it is advantageous to know the botanical name of a crop. The botanical name consists of a genus name and a species name. Crops with the same genus name are closely related botanically and have some similar characteristics. Common names often vary between different geographical regions. It might be helpful at times, when talking to growers from another state or region, to know the botanical name to identify if one is talking about the same crop with a different common name.
Sowing time The sowing times given are generally recommended for producing the highest yields of the crop. These times might have to be adapted in view of local conditions and a specific farm management purpose.
Root system The root system accounts to a large extent for a green manure’s soil improving properties. The growing root tips open up soil pores. A deep taproot will bring nutrients to the surface. A strong fibrous root system adds a lot of organic matter to the soil. The breakdown of the organic matter produces compounds that bind soil particles
28 together to form soil aggregates. A well-aggregated soil tills easily, is well aerated, has a high water infiltration rate, and, in combination with organic matter, an improved water holding capacity.
Average biomass/ N per ha Data on biomass were not available for all crops. Figures in t/ha indicate the average fresh biomass a crop will have produced by the time of incorporation. When dry matter figures are quoted, these are stated as ‘dry matter’. Dry matter figures for biomass are derived from harvesting and then oven drying fresh biomass. Biomass produced is directly related to the health of the crop and the length of growing time. Hence the great range of expected yields. Where only one figure is given, this is an average or the data from one published measurement. For some legumes, data was available on the assimilated kg of nitrogen per ha added to the soil by the crop when incorporated. This is noted in the list.
[Allelopathic] Suppression of weeds, vegetable pests and diseases Allelopathy refers to plants or microorganisms producing organic compounds that stimulate or inhibit the growth of neighboring plants or microorganisms. In this column, data is given on the effects of green manure crops on weeds, vegetable pests and diseases. Weeds, pests or pathogens may be suppressed through an allelopathic affect. Weeds may also be suppressed by the strong competition, mainly for light, from the green manure crop. Pests and pathogens can also be suppressed because the green manure crop acts as a ‘break crop’, i.e. it is not a host to the pest or disease.
Host of vegetable diseases and host of vegetable pests Most crops are susceptible to diseases. Most of these diseases are crop specific. For example, the cereal root disease ‘Take-all’ (Gaeumannomyces graminis) does not affect vegetables. Some pests and diseases, however, attack green manure as well as some vegetable crops and it is important to weigh up the potential risks and benefits. Pests and diseases might proliferate in the green manure and attack the following crop. On the other hand, a low level incidence of pests in the green manure crop may not excessively diminish the green manure’s growth and have the benefit of being a food source for survival of beneficials that will then protect the cash crop.
Host/habitat for beneficial insects An important function of green manure and cover crops is to provide food and shelter for beneficial insects. Most crops do this to some degree. Prolific bloomers, especially, are a source of nectar and pollen, an important food source for insects. Some crops are well known for supporting beneficial insects and they have been listed.
Can be sown in combination with Planting a mixture of green manures instead of a monoculture makes use of synergies between the crops. Soil microbial communities are more diverse under species-diverse pastures than under monocultures. Listed are commonly used combinations of crops, but other combinations are also possible.
Other comments The last column lists a range of other additional important features that are not part of the main characteristics to be considered when choosing a green manure or cover crop.
The advice provided in this publication is intended as a source of information only. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
29 annual/p Green eren- Avg [Allelopathic] Suppression manure/Cover nial Botanical Sowing Biomass/N of weeds, vegetable pests & Host of vegetable Host/habitat for Can be sown in crop (a),(p) name time Root system per ha diseases diseases Host of vegetable pests beneficial insects combination with Other comments Legumes Birdsfoot Trefoil p Lotus autumn, highly 8 t/ha; 30- Helicoverpa punctigera minute pirate bug slow-growing grasses tolerates droughty and corniculatus spring branched 30- 180 kg N/ha (previously Heliothis ), Lygus (Orius tristicolo r) waterlogged soils; contains 60 cm depth (nitrogen per spp. tannin, which, when grazed, ha) reduces need for drenching lambs; slow regrowth after
Biserrula a Biserrula autumn deep (0.70- 4-7 t/ha some tolerance to Red lucerne flea, vegetable weevil, sub-clover, best on acidic sandy soils pelecinus 1.2 m) Legged Earth Mite (RLEM) & jassids, Helicoverpa spp., Serradella Blue Oat Mite (BOM) aphids Clovers Trifolium spp. taproot with 4 - 10 t/ha generally weed suppressing Pythium spp.; species dependent most generally pollen and spreading when fully established; fast Sclerotinia spp. nematode species: root-knot nectar food for branched initial growth is important nematodes Meloidogyne beneficial insects; laterals; spp., root-lesion nematode lacewings, spiders rhizomes; (Praylenchus penetrans ), stolons clover cyst nematode (Heterodera trifolii ), stem & bulb nematode (Ditylenchus dipsaci ), Xiphinema spp., Tylenchorhynchu s spp., Paratylenchus spp., RLEM, lucerne flea, cowpea aphid, alfalfa aphid
Arrowleaf clover a Trifolium early deep 5.5-11 t/ha Rhizoctonia solani; RLEM, lucerne flea at annual grasses resistant to bean yellow mosaic vesiculosum autumn to but no significant seedling stage virus; intolerant of alkaline soil mid-winter diseases recorded in Australia
Balansa clover a Trifolium early extensive 5-6 t/ha tolerant of RLEM, when Pythium spp at RLEM, lucerne flea, lucerne Persian clover, sub- moderately tolerant of salt, michelianum autumn dryland; 7-8 mature seedlling stage; aphid at seedling stage clovers; salt tolerant water logged soils and drought t/ha under alfalfa mosaic virus grasses; tall wheat irrigation grass; annual & perennial clovers, annual grasses;
Berseem clover a Trifolium early up to 60 cm 10 t/ha early vigorous establishment cucumber mosaic plant parasitic nematodes in bees & other white clover, oat, alexandrinum autumn needed for weed suppression; virus limited numbers, esp. pollinating insects; cereal rye, annual rye does not suppress fathen or Meloidogyne spp.; nectar food for many grass mallow insects Crimson clover a Trifolium late deep taproot 5-8 t/ha; 54- less weed suppressing than blue-green aphid, pea aphid, bees, ladybirds, cocksfoot, white & decomposes rapidly, when incarnatum summer 85 kg N/ha more prostrate clovers Lygus bug; thrips; several bigeyed bug sub-clover, burr incorporated; higher water use early nematode species incl. (Geocoris sp), medic, cereal grains, efficiency than hairy vetch autumn Meloidogyne hapla and M. minute pirate bug vetches, annual arenaria (Orius tristicolor ) ryegrass, tall fescue Persian (Shaftal) a Trifolium late dense 8-15 t/ha; 85- quick ground cover for weed RLEM, lucerne flea bees & other tall wheat grass in tolerates medium salty and clover resupinatum summer to 160 kg N/ha suppression pollinating insects; water logged areas; water logged soils; excellent autumn nectar food for many other clovers regrowth after slashing insects
30 Red clover short Trifolium early taproot to 90 5.5 t/ha; 1.6- allelopathic affect against wild Fusarium oxysporum ; root-lesion and root knot ladybirds, hoverfly, can be interplanted some varieties tolerate water lived p; a pratense autumn cm, 2.2 t/ha dry mustard; suppresses weeds; common pea mosaic nematodes lacewings, wasps into short crops only logged soils; some varieties spreading matter; 50 kg virus; cucumber resistant to Sclerotinia crown rot branched N/ha mosaic virus; Allfalfa laterals top 12 mosaic virus; cm Sclerotium rolfsii
Rose clover a Trifolium hirtum autumn taproot up to 7 t/ha; nematodes Meloidogyne Orisius sp. sub-clovers; barrel drought tolerant 12 cm 75 kg N/ha incognita & M. javanica medic; lucerne; perennial grasses Strawberry clover p Trifolium spring taproot to 1m, 3.7-11 t/ha; vigorous stand has a low, Sclerotinia sp.; RLEM, BOM, stem & bulb beneficial insect tall wheat grass, tolerates waterlogged soils & fragiferum in wet and 40-330 kg thick weed smothering growth nematode, cyst nematode, attractor puccinellia, white medium saline soils; medium saline soils N/ha habit Meloidogyne hapla , but not clover, perennial rye drought resistance the roots good host for M. incognita grass, phalaris, tall remain in the and M. arenaria fescue, top 8-10 cm Sub-clovers a Trifolium autumn taproot with 3.3-9.5 t/ha; smothering weeds; St. John’s Fusarium sp., Lygus bug, several nematode ladybirds, Geocoris medics, annual and tolerates temporary flooding, subterraneum fibrous 100-225 kg Wort (Hypericum Rhizoctonia sp., species sp. prennial grasses, drought; can be serioius weed in supporting N/ha perforatum ) Aphanomyces sp. , lucerne annual vegetables; loosens roots red leaf virus compacted soil Sweet clovers a; Melilotus spp. autumn strong taproot 2.5-9 t/ha weeds due to quick growth; bees, large tall wheat grass; tolerates salinity & water logging; biennual Sclerotium rolfsii ; nematodes predatory wasps, cereals toxic to livestock; drought Tachinid flies, resistant; alleviates soil compaction Sweet clover Mellilotus autumn strong taproot monocotyledons, such as mellanensis barley (Hordeum vulgare ), onion (Allium cepa ) White clover p Trifolium autumn shallow, most 12-25 t/ha; smothers weeds; may reduce Pseudomonas Lygus bugs, many arthropods, bees, other clovers, medics, repens roots to 20 1.6-3.5 t/ha thrips and brassica pests syringae, Sclerotium mites; many nematode aphidophagous grasses, but grasses cm; stolons; dry matter; when intercropped; rolfsii, Rhzoctonia, species, Western Flower insects (hover flies, difficult to maintain taproot may 40-270 kg Fusarium, Thrip, many arthropods, lacewings, predatory reach 90 cm N/ha Colletotrichum spider mite midge, predatory myrid, lady beetles)
Cow pea a Vigna late spring, strong 4-5 t/ha; 2.2 suppresses weeds through Fusarium oxysporum cowpea aphid; Meloidogyne bees, Japanese millet, moderaterly drought resistant, unguiculata summer taproot, t/ha dry vigorous growth; suppressed spp.; leafminers, leafhoppers, ladybirds,predatory sorghum, soybean, because taproot draws moisture laterals near matter; 70- in green house experiment mites, thrips, aphids wasps, ants, soft- peanut from deep in the soil profile surface; 350 kg N/ha Meloidogyne arenaria, M. winged flower beetle incognita, Heterdodera
Fenugreek a Trigonella autumn deep taproot 1.5 t/ha dry Rhizoctonia solani , Fusarium field bean, cereals some drought and salt tolerance foenum- matter oxysporum (Wilt), (barley) graecum Meloidogyme incognita
Field pea a Pisum sativum (early) shallow 6.5-9.5 t/ha; Fusarium wilt, aphids, Lygus bugs; plant aphid predators, eg. cereals (usually oats, on its own not vigorous enough autumn 3 t/ha dry Aphanomyces, parasitic nematodes 7-spotted ladybird but also rye,barley, to suppress weeds matter; 30- Sclerotinia (Coccinella wheat); brassicas 140 kg N/ha septempunctata ), syrphid flies; bees, native pollinators
Guar (a grain a Cyamopsis late spring deep rooted green vegetable bug; myrid infertile soils; other name Cluster legume) tetragonoloba to summer sucking insect; Bean
31 Lucerne p Medicago late deep taproot 8 t/ha dry clover seed; Sclerotium rolfsii Alfalfa mosaic virus nematode Pratylenchus food & shelter for grasses there are winter active and sativa summer, matter penetrans beneficial insects; winter dormant lucerne varieties spring assassin bug; Orius spp . Lupins a Lupinus spp. early strong deep 10 t/ha; Sclerotinia ; cucmber RLEM, native budworm; ladybirds; bees; wheat species vary in pH preference; autumn taproot depending mosaic virus; several Heterodera and important honey alkaline tolerant species do not on variety 60- Rhizoctonia, Meloidogyne nematode plant; like free lime; iron deficiency on 350 kg N/ha Anthracnose ; bean species; thrips calcareous soil yellow mosaic virus Medics a Medicago spp. autumn; deep 8 t/ha; 55 - RLEM; nematode lacewings, deeper rooted and more drought early spring 220 kg N/ha Pratylenchus spp. hoverflies tolerant than sub-clovers
Serradella a Ornithopus spp autumn deep 3-6 t/ha aphids Rhizoctonia sp., Helicoverpa punctigera ryegrass, fescue; best on acidic soils Colletotrichum sp. (previously Heliothis ) clovers, Biserrula Soybean, trailing Glycine soya or summer 4 t/ha weed suppressing insect attraction millet, cowpea, sweet G. max corn Vetch a Vicia spp. early possibly lettuce Lygus bug ladybirds, Geocoris autumn, sp spring, summer Hairy vetch a Vicia villosa early taproot 30-90 4.8-7.8 t/ha; flower thrips (Frankinella aphid predators, wheat, oats, cereal toxic to cattle; nematode autumn, cm 2.2-5.6 t/ha spp) ; many nematode Orisius sp ; rye, barley resistant; more winter hardy than spring, dry matter; species; aphids, Lygus bug, Geocoris sp., soil common vetch; high water use summer 90-150 two-spotted spider mite, thrips arthropods, efficiency kgN/ha Purple vetch a Vicia spring to 4.8-7.8 t/ha; suppresses weeds, especially Two-spotted mite; bees, many benghalensis summer 2.2-5.6 t/ha star thistle Heterodera spp., beneficial insects or V. dry matter; Pratylenchus vulnus ; possibly (assassin bug atropurpurea 55-225 kg Meloidogyne javanica Apiomerus spp., N/ha Orius sp ., lacewings, ladybirds) Wooly Pod vetch a Vicia early taproot to 80 6.5 t/ha weed smothering major host for cereals, especially toxic to cattle benghalensis autumn cm Sclerotinia minor oats Other broadleaf crops
Brassicas a contain glucosinolates, basic clubroot aphids, caterpillars, snails, Brassicas can be grown for substances for (Plasmodiophora slugs biofumigation; in general high isothiocyanates, substances brassicae ), downy glucosinolate varieties are more which suppress soil mildew (Peronospora effective as biofumigants; pathogens: fungi and parasitica ) brassica crops vary in content nematodess; also spiny and type of glucosinolates and sowthistle (Sonchus asper) , biofumigant effectiveness; scentless camomille research on glucosinolate, pest (Matricaria inodora ), smooth and disease interactionsand pigweed (Amaranthus breeding hybrids to maximise hibridus), barnyard grass biofumigant effect is ongoing (Echinocloa crusgalli) , meadow foxtail (Alopecurus myosuroides Huds), wheat
32 Canola a Brassica napus autumn deep taproot 5.5-7 t/ha nematode Rotylenchus Rhizoctonia, nematodes; cabbage moth host for beneficial field peas be aware of GMO status 3.3 t/ha dry reniformis Sclerotinia (Plutella xylostella ) insects: Nabis spp, matter sclerotiorum Geocoris spp, Orius spp, Collops spp and Coccinelids Yellow or White a Sinapis alba or spring to shallow nematodes; some potential to Rhizoctonia; clubroot turnip aphid (Hyadaphis ladybirds; hoverflies field peas mustard Brassica alba early reduce wireworm and slugs; erysimi ) ; cabbage aphid or B. hirta autumn allelopathic effect against (Brevicoryne brassicae ); weeds thrips Indian mustard Brassica spring to taproot 5.5-9.5 t/ha juncea early dry matter autumn Fodder brassicas a autumn shallow 10-15 t/ha dry matter Sunflower a Helianthus spring to strong 4-5 t/ha dry nematodes; sweet corn (Zea Sclerotinia Helicoverpa spp. arbuscular annuus summer taproot, matter mays) , sorghum (Sorghum sclerotiorum mycorrhizae (AM) lateral vulgare), Guar branches Marigold a Tagetes minuta spring to nematodes summer Cereals and Grasses Barley a Hordeum late strong, 7.5-17.5 flailed barley inhibits cereal host for nematode damsel bug, brome,cereal rye, vulgare summer, fibrous t/ha; more rye; strong tillering at base, Meladoigyne javanica; minor (Nabidae sp.), annual clovers, autumn, than oat, hence better weed control host for M. arenaria Encyrtidae medics, vetch; pea- early spring cereal rye, than oats, rye, wheat parasitoid of barley-white mustard wheat cutworm larvae Oats a Avena sativa autumn fibrous 9-13 t/ha non- or poor host to nematode cereal rye, which Meloidogyne hapla increases mycorrhizal colonisation
Cereal rye a Secale cereale autumn fibrous; 4.5-11 t/ha rye residues on the surface nematodes Ditylenchus ladybirds Berseem clover, oats drought resistant stronger than suppress: sweet corn, weeds dipsaci , Heterodera avenae , other cereals (pigweed, barnyard grass, Aphelenchus tritici , fathen (Chenopodium album ); Meloidogyne arenaria non- or poor host to nematode M. hapla , Pythium spp.,
Wheat a Triticum spp autumn fibrous 4-9.5 t/ha stem & leaf residues several nematode spp. damsel bug, soybean suppressed annual ryegrass (Nabidae sp.), (Lolium rigidum ) in laboratory Encyrtidae trial; cultivar dependent parasitoid of
Millets a Japanese millet a Echinochloa spring, fibrous, up to 35 t/ha; weed smothering ; nematode Meloidogyne arenaria, soybean; cowpea more cold tolerant than Siberian utilis or E. summer mainly top 4-7t/ha dry Paratylenchus projectus M.incognita, M. javanica millet crusgalli soil matter
33 Siberian or White a Echiniocloa spring, fibrous, up to 35 t/ha; weed smothering through opt. Temprature 25-30°C; grows Panicum millet frumentacea summer mainly top 4-7 t/ha dry prostrate growth more slowly than Jap. millet; soil matter better regrowth after grazing or slashing Forage (Pearl) a Pennisetum sp. spring, larger and suppresses weeds through growth habit similar to sorghum millet summer deeper than vigour Japanese millet Puccinellia p Puccinellia autum, late tall wheat grass, main use for reclamation and ciliata winter, early strawberry clover ground cover of very saline & spring waterlogged soils
Sorghum/ Sudan a Sorghum spring, fibrous 16-22 t/ha wheat; nematodes root-lesion nematode cowpea produces more biomass, if not grass vulgare summer Meloidogyne hapla ; weeds Pratylenchus penetrans ; corn cut aphid Tall wheat grass p Thinopyron winter to puccinellia, tall used for reclamation and as ponticum spring fescue, phalaris, ground cover of saline & water strawberry clover, logged soils white clover, balansa Ryegrass a; p slugs, snails, RLEM, BOM Annual ryegrass a Lolium rigidum early extensive, will become a weed, if let go to autumn shallow seed Perennial ryegrass p Lolium perenne autumn to extensive, clovers; allelopathic effect Legumes (white, red, early spring shallow against weeds subterranean clovers, lucerne), temperate grasses (fescue, cocksfoot, phalaris)
References This list was compiled from numerous information sources. Much information can be found on the web through a web search (Google or other). For Australian conditions, useful sources are publications by the Australian state government departments for agriculture and primary industries: New South Wales Department of Agriculture: www.agric.nsw.gov.au Department of Primary Industries, Water and Environment, Tasmania: www.dpiwe.tas.gov.au Department of Primary Industries, Victoria: www.nre.vic.gov.au Department of Primary Industries, Queensland: www.dpi.qld.gov.au Primary Industries and Resources South Australia: www.pir.sa.gov.au Department of Agriculture, Western Australia: www.agric.wa.gov.au Very comprehensive is the Cover Crop Database from the University of California at www.sarep.ucdavis.edu/.
Please note: Information on this list is current at the time of publication. New information through research is constantly produced, for example in relation to biofumigants. For explanations of column headings, refer to the cover pages. The advice provided in this publication is intended as a source of information only. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
34 Soil Quality Assessments (form provided by Chris Alenson)
Date: Location of sampling:______(mark on property sketch) Soil type: ______Soil moisture at sampling:: dry/moist/very wet Plant/animal productivity:______Cropping:______Problems: Soil Quality Poor Medium Good Assessment Card Indicators 1------2------3 4------5------6 7------8------9 Poor Medium Good 1 2 3 4 5 6 7 8 9 Soil 1. Few aggregates, powdery, 1. Some aggregates present giving 1. Good soil aggregation, friable with Characteristics clods, difficulty with cultivation fair structure, soil clods present but good structure, no clods evident clods break with pressure Soil structure/tilth Water stable aggregates 2. Few if any water stable 2. Some aggreagates are water stable 2. Many aggregates are water stable aggregates Soil crusting 3. Surface crusting affecting water 3. Some crusting limited affect on 3. Soil surface porous, no evidence of penetration and seedling seedling emergence and water soil crusting emergence penetration Compaction 4. Obvious soil compaction , tight 4. Some soil compaction, limiting 4. No compaction evident, root layers limiting root penetration root penetration and water movement. development and water movement (often horizontal growth), and Metal rod penetrates with difficulty unrestricted. Metal rod penetrates water movement. Metal rod will easily. not penetrate. Organic matter 5. Pale bleached colour -little 5. Light brown soil colour-some plant 5. Dark soil colour, decomposing plant obvious organic matter in soil, material, some crusting and soil clods material, friable structure compacted, cloddy, crusted Soil slaking 6. Soil collapses when wet into a 6. Some soil collapse when wet, but 6. No soil collapse when wet, structure mush some structure remains remains Hydrological indicators 7. Water infiltrates very slowly, 7. Slow water infiltration with some 7. Infiltration -excellent, no ponding ponding evident, runoff obvious ponding and runoff little runoff except in excessive rainfall Water infiltration with signs of erosion. Erosion 8. Obvious soil erosion -rills, 8.. Some signs of soil loss 8. No soil loss evident sheet and gully erosion evident Water logging 9. Obvious water logging in soil, 9. Some signs of water logging 9. No signs of water logging water collects in low areas. Biological indicators 10. Obvious fibrous root mat just 10. Some indication of root mat 10. No evidence of root mat below surface restricting root, Root mat water and oxygen penetration Plant roots 11. Restricted root development, 11. Moderate root development some 11. Fibrous and deep root systems with few fine feeder roots, some roots fine feeder roots good colour discoloured and rotting
35 Soil Quality Poor Medium Good Assessment Card Indicators 1------2------3 4------5------6 7------8------9 Poor Medium Good 1 2 3 4 5 6 7 8 9 Nodulation 12. Poor nodulation on legumes- 12. Fair nodulation of legumes- 12. Good nodulation of legumes with green yellow when broken open colourpink/reddish when broken pink/red colour when broken Earthworms 13. Few signs of earthworm 13. Some worms evident, some worm 13. Many worms evident, channels activity- no worm burrows channels and castings and castings Worm channels 14. Few if any worm channels 14. Some worm chanels evident 14. Many worm channels evident Dung beetles, ants, 15. Few if any life forms, dung 15. Some life forms including dung 15. Dung beetles and other life forms termites other life forms beetles, manure remains as beetles visible -manure shows signs prolific-decomposition of manure piles deposited for some time of decomposition within days rapid Smell 16. Stagnant smell 16. Little or no smell 16. Fresh moist earthy smell Plant and animal 17. Variable crop and animal 17. Uneven productivity in crops and 17. Good crop and animal productivity. productivity productivity with stunted growth animals with some crop disease and No problems with disease or animal and some disease in crops, animal occasional animal health problems. health. health problems evident. Possible nutrient deficiency No obvious nutrient deficiencies Nutrient deficiencies obvious symptoms Chemistry 18. pH either too acid (lower than 18. Slightly acid (approx 6.00 or 18. Ph levels between 6.00-7.00 5.5) or too alkaline (greater than below) or slightly alkaline (approx adequate range for most crops pH 7.5) for optimum crop production 7.5 ) for optimum crop production Cation Exchange 19. Low CEC (5-10 meq) 19. Medium CEC (10-15meq) 19. High CEC(15->20meq) indiactes indicates low storage pantry for indicates medium storage capacity of good storage capacity for major Capacity (CEC) major cations, Ca, Mg, K a, Na major cations, Ca, Mg, K a, Na and cations, Ca, Mg, K a, Na and trace and trace elements trace elements elements Organic matter 20. Less than 3% 20. Between 3-5% 20. Greater than 8.0% Nutrient levels 21. A number of test levels are 21. A couple of nutrient levels are 21. No nutrient deficiencies , levels inadequate for normal plant inadequate for crop growth, no visual adequate for crop production Soil analysis growth element deficiencies
Management changes( Record management changes that might be required to redress problems encountered)
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