Stockless Organic Farming in the UK S13
Stopes, C. ; Bulson, H. & Welsh, J.
Elm Farm Research Centre, Newbury, RG20 0HR, UK.
|Most organic farms in the UK operate a rotation
with both crops and livestock. Organic conversion in arable areas may depend on the
development of viable stockless organic systems. The impact of such systems on crop yield,
soil fertility, weeds, pests, diseases, and the environment has not been studied in the
A fully replicated experiment at EFRC has examined three, four year rotations for two complete crop rotations (since 1987-88). Each rotation includes one year cut and mulched legume green manure, and three cashcrops: A - red clover, winter wheat, winter wheat, spring oats; B - red clover, potatoes, winter wheat, winter oats and C - winter wheat, winter field beans, winter wheat. Every course of every rotation was grown in every year with three replicates.
Crop rotation has had a significant effect on the agronomic performance. Growing two winter wheat crops in succession (rotation A) resulted in an unacceptably low yield and very high weed levels in the second wheat. The inclusion of winter beans between the two wheat crops (rotation C) improved the yield and reduced weed levels of the second wheat. The winter wheat after potatoes (rotation B) produced a relatively good yield with low weed growth.
There was no evidence of decreasing soil P and K levels in spite of high nutrient off-take (in rotation B in particular), nor was there evidence of deterioration in soil structure (bulk density). However, organic matter did decline. Weeds levels did not increase over time although rotation did affect weed populations; the inclusion of potatoes and winter oats (rotation B) resulted in relatively low weed growth. The performance of the green manure in the preceding year did not influence the yield of the following crop, crop establishment and growing conditions were more important in determining crop performance.