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Book of Abstracts First Legume Society Conference 2013: A Legume Odyssey Novi Sad, Serbia, 9-11 May 2013
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The environmental benefits of incorporating legumes into arable systems
Kairsty Topp, Christine Watson
Crops and Soils Systems, SRUC, Edinburgh, UK
Cultivated legumes are an important source of protein for humans and livestock. Currently, the
EU import approximately 30 million tonnes soya annually, much of which comes from South
America. Some of the demand for protein could be supplied from home grown legumes. In
addition to meeting the protein demand, home-grown proteins deliver a unique combination of
ecosystem services: food, feed, resource conservation and direct mitigation of adverse impacts on
the environment. The purpose of this paper was to quantify the impacts of incorporating peas
into a typical UK crop rotation to assess the implications on pollutants and pesticide use. The
Farmscoper tool has been used to conduct the analysis. The non-legume crop rotation is winter
barley, winter oil seed rape, winter wheat, winter wheat. This is compared against a legume
rotation where a pea crop is incorporated between the two winter wheat crops. Standard
recommendations for fertiliser applications have been assumed. For the winter wheat following
the pea crop, the nitrogen fertiliser has been reduced by 30 kg N/ha, thus allowing for a carryover
effect from the nitrogen fixed by the pea. The results indicate that annual average level of
ammonia, nitrous oxide and pesticide declines; however, there is an increase in nitrate,
phosphorus and sediment. This is likely to be due to the higher nitrogen in the crop residue
compared to other crops, and the increased length of time when there was no crop coverage.
Nevertheless, these results do not incorporate any effect of legumes on improved soil structure.
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