The Journal of Agricultural Science




CROPS AND SOILS

Integration of nitrate cover crops into sugarbeet (Beta vulgaris) rotations. II. Effect of cover crops on growth, yield and N requirement of sugarbeet


M. F. ALLISON a1 p1, M. J. ARMSTRONG a2, K. W. JAGGARD a1 and A. D. TODD a3
a1 IACR Broom's Barn, Higham, Bury St Edmunds, Suffolk IP28 6NP, UK
a2 British Sugar plc, Holmewood Hall, Holme, Cambridgeshire PE7 3PG, UK
a3 IACR Rothamsted, Harpenden, Hertfordshire AL5 2JQ, UK

Abstract

Between 1989 and 1993, 17 experiments tested the effects of autumn-sown cover crops on the yield, processing quality and N nutrition of subsequent sugarbeet crops. Cover crops had no effect on sugarbeet plant population density or pesticide requirement. In nitrogen response experiments, the mean beet yield at the economic optimum was 83 t/ha. The mean N fertilizer requirement was 96 kg N/ha and the N uptake at maximum yield averaged 180 kg N/ha. Cover crops had no effect on yield, fertilizer requirement or N uptake. In addition, cover crops generally had no effect on the efficiency of N fertilizer use, the mineralization of N from the soil organic matter nor the amount of soil mineral nitrogen at sowing or at harvest of the beet crop. Processing quality was also not affected by cover crops. The cost of growing a cover crop ranged from 0 to 50 £/ha. Since these costs cannot be offset against increases in yields or reduced fertilizer application rates, cover crops need to be low cost, i.e. cheap seed and minimal cultivation. Cover crops using volunteer cereals and weeds or farm-saved grain that are established with a single stubble-cultivation should fulfil these criteria.

(Received June 18 1997)


Correspondence:
p1 Present address: Cambridge University Farm, Huntingdon Rd, Girton, Cambridge CB3 0LH, UK. E-mail: mfa22@cam.ac.uk


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