A study of mole drainage with simplified cultivation for autumn-sown crops on a clay soil

Abstract

SummaryGrain yield of winter barley in the year preceding the experiment (1978) was relatively uniform over the site. In 1978–9 after the drainage treatments had been introduced, growth and yield of winter wheat were not affected by drainage, probably due to a compact layer at 20 cm that prevented the mole drains from controlling the water table (Harris et al. 1984).In 1979–80 after disrupting this layer, root growth in undrained plots during the winter and spring was severely restricted by the presence of a water table 20 cm from the soil surface, although some root axes were able to grow down to 75–100 cm below the soil surface. The differences in root distribution patterns between drained and undrained plots disappeared after the water table declined in April. Uptake of nitrogen, phosphorus and potassium were less on undrained plots. Dry-matter production, leaf area index and peak number of tillers was also depressed, so that the yield of winter wheat was 0·74 t/ha greater on the drained treatment; the grain from the drained plots contained fewer impurities and weed seeds.