Organic conversion strategies for stockless farming
About this project
Legume-containing leys are used to improve soil fertility in the two-year organic conversion period. While in-conversion land may be grazed, it is effectively out of production in stockless farming systems, potentially resulting in a reduction in income and pressure on cash flow. The effects of seven conversion strategies on a subsequent organic winter wheat crop were investigated on a sandy loam and a sandy clay soil. Experimental data were then used in a mixed integer programming model to examine the effects of whole-farm conversion on farm profitability. The strategies were: 1. two-years' red clover-ryegrass green manure, 2. two- years' hairy vetch green manure, 3. red clover for seed production, then a red clover-ryegrass green manure, 4. spring wheat undersown with red clover, then a red clover green manure, 5. spring wheat, then winter beans, 6. spring oats, then winter beans, 7. spring wheat undersown with red clover, then a barley-pea intercrop.
In-conversion crop yields were generally low and undersown wheat failed completely. Conversion strategies had a significant impact on organic wheat yield, which ranged from 2.8 to 5.3 t ha-1. This was attributed to differences in organic wheat establishment, caused by variation in soil structure due to the different conversion strategies. Organic wheat yield was not related to weed abundance or soil mineral nitrogen.
In the absence of a specialised clover seed market, two years' red clover-ryegrass was the best conversion strategy for a risk-averse individual, due to the subsequent income from the high-yielding organic wheat. Growing oats followed by beans was a medium risk, medium return option, useful when labour supply is limiting and stable cash flow a priority. However, such a strategy may not currently qualify for organic farming scheme payments. Given current prices and experimental yields, investments were always recouped and should not necessarily deter growers from conversion. On a 250 ha farm with (without) current subsidies, organic prices could fall by 26% (34%) before organic and conventional production were equally profitable.
A relaxation in the requirement for fertility-building phases during conversion, the expansion of domestic red clover seed production and the development of the market for in-conversion produce are recommended.
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