Problem solving

Does your soil analysis indicate that you should be getting a better response from the crop? In this situation, always suspect nutrient imbalance. An Albrecht style analsis should help to correct this problem. For many Australian soils, the solution is calcium or calcium and magnesium (supplied by lime or dolomite). It may also be necessary to take leaf samples for testing. Comparison of soil and leaf test results through the growing period should reveal what is happening to soil nutrients and if the problem is availability, rather than gross nutrient levels. Whereas foliar fertilisers should not be the basis of an organic nutrition program, they may be needed to get nutrients into plants while soil imbalances are corrected. They are also useful at other times of stress, such as this year in southern Australia, when soil temperatures in spring remain too cold for roots to be fully operational (we just had the coldest October in 57 years).

Keep it simple, and plan for conversion

Generally the solution to fertility problems does not rely on using dozens of different products. Start with a soil test. Improve organic matter and adjust soil mineral balance as a priority. Apply NPK and trace elements as permitted by the budget after correcting soil balance, otherwise these products may well not work effectively.

Soil management and development does cost money, and therefore it should be considered as (an important) part of the conversion plan.
Alkaline soils

Very alkaline soils do present a significant problem in broadacre organic production. There is a tendency for researchers in this field to imply that this indicates a failure of certification systems to address Australian conditions, to claim that organic agriculture in broadacre situations is unsustainable and to press for ‘exceptions’ to the internationally accepted rules. While not wanting to close debate on these issues, I perceive this response to be short on understanding of and commitment to organic production. It is true that alkaline soils are a significant challenge but there may yet be ways around the issue.

Firstly, there are undoubtedly areas under agricultural production that are so marginal they would be best taken out of farming and dedicated to conservation uses, or shifted to some form of tree-based agriculture. Large areas of the Eyre Peninsula (SA) and some parts of the WA wheatbelt are in this category.

There are also other avenues for experimentation. Phil Barnett from APAL says “there has been very little work done on organic production in alkaline soils. Most of the Albrecht work, for instance, is done overseas in acid soils, and a lot of rock phosphates have up to 30% calcium, which is rather throwing fuel onto the fire. Biological farmers [he means transitional farmers] who do not have to conform to certification rules may use MAP, which is quite acidic. Sulphur is also important, so they could use sulphur-coated MAP. They also cannot obtain trace elements, so these are used as foliar fertilisers. Most also use seed dressings, to get the nutrition into the plant early.”

Phil continues “organic growers may use sulphur blends, but it is very difficult indeed to change pH in a broadacre context. They also try to increase organic matter in every available way, especially P-scavenging plants as green manure. They can use foliar fertilisers for trace el;ements and seed dressings, if these are acceptable to the certifiers. Some compost products available, such as those from Laurie and Co or Nutri-Tech Solutions, combine humates, crushed-rock fertilisers, trace elements and inoculations of soil organisms, in an attempt to chelate these products before adding them to soil, and make them more available’.

Other interesting areas of research are the permanent bed systems more common in the USA, or adaptations of these systems, such as the one being developed by Gavin Dunn at Tarlee (SA). These systems either concentrate on soil improvement only in the planting zone (i.e. they do not attempt to apply to the traffic area between the raised beds) or they try to maximise the effect of organic matter breakdown from the residue of the previous crop. In one such system, a series of swales and ridges are established. Seed is planted Inter-row cultivations in the standing crop may throw soil further up onto the ridges. The residue is then rolled into the gully to compost. Next years ridge is built on top of last years swale (which contains the decomposing residues).

Use of compost and fertiliser combinations and the placement of these products with respect to the seed are also interesting areas for experimental work. The banding of high rates of compost (for broadacre situations) and bio-phosphate products under or alongside the seed is of special interest, particularly for crops such as wheat where phosphorus nutrition is establish early in the life of the plant.

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