Forage Mulch as a Multifunctional Tool in Organic Wheat Production

Dr. Andy Hammermeister, Stuart McMillan, and Dr. Ralph Martin

The benefits of increasing the level of soil organic matter on all aspects of soil fertility and soil quality are well recognized. These benefits include an improved long term nutrient supply, improved aeration and moisture retention, and reduced erosion and compaction. The amount of improvement in soil fertility and quality, however, will vary with the amount and type of plant residue added to soil. In studies showing an increase in soil quality under organic management, most of the benefits have come from greater residue return to the soil, particularly under pasture or other systems producing large quantities of plant material.

On organic livestock farms, therefore, the use of pasture is an obvious way of improving soil fertility and quality. However, an increasing number of organic farms do not produce livestock and therefore have no direct need for perennial forages (i.e. hayland). Also, hay production for off-farm sales would mean that nutrients would be exported from the farm, thus reducing the benefits of forage for the farmer and decreasing soil fertility in the long run. Therefore, there is a need to assess the most effective ways of improving soil fertility and quality in stockless organic systems.

The search for effective methods of using pasture for soil improvement in stockless farming systems has led to the idea of applying forage as a surface mulch. Forage applied as mulch can still contribute to soil fertility, improve soil quality, reduce weed numbers, and influence the insect community. However, the success of this method will be influenced by many agronomic variables, including mulch harvesting method, application time, and application rate. These factors are manageable and under the control of the producer, so appropriate research can contribute to the development of a system that suits the needs of stockless organic farmers. Therefore, researchers at the Organic Agriculture Centre of Canada are now conducting trials to assess different application methods for forage mulches.

The trials are being conducted on Helena wheat that was seeded after pasture breaking. A pasture mixture (Timothy/Red Clover) was broadcasted evenly across the plots and the pasture was either chopped with a flail mower or harvested unchopped with a disc mower. The mulch was applied at one of two different times (early - at wheat emergence, or late - at the 3-leaf stage), and at one of four different rates (0, 1, 2, or 4 tons of forage/hectare on a dry weight basis, applied as fresh cut mulch). The experiment will examine the influence of the different harvesting methods, application times, and application rates on wheat plant populations and soil properties.

To date, the results have shown that forage mulch application increases soil moisture. Also, increasing mulch application rates reduces wheat plant populations. Final results will be posted when they become available.

Researchers:
Dr. Andy Hammermeister, Stuart McMillan and Dr. Ralph Martin
Nova Scotia Agricultural College/OACC
P.O. Box 550
Truro, NS B2N 5E3
Contact: Ralph Martin: E-mail: rmartin@nsac.ca
Tel: 902-893-6679

Collaborators:
Dr. Martin Entz and Matthew Weins (M.Sc student)
University of Manitoba Dept. of Plant Science
222 Agriculture Building
Winnipeg, MB R3T 2N2
Web site: www.umanitoba.ca


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