EFFECTS OF DIFFERENT METHODS OF CULTIVATION AND DIRECT DRILLING, AND DISPOSAL OF STRAW RESIDUES, ON POPULATIONS OF EARTHWORMS

Numbers of earthworms collected from direct‐drilled or ploughed land were studied during successive years on contrasting soil types sown with cereals. Samples were taken in autumn using a combination of chemical expulsion and hand sorting of soil. The population was consistently larger on direct‐drilled than on ploughed land, and the difference became greater in each successive year. Deep burrowing species were affected similarly to the population as a whole. Population differences on the two treatments were greater with spring — than autumn ‐ sown crops. After tine cultivation numbers were usually similar to those after ploughing. On a direct‐drilled clay soil on which straw had been either burned, or chopped and spread, no differences were recorded in the overall population. However, significantly larger numbers of deep burrowing species were found on the chopped and spread areas, whereas on the burned areas numbers of Allolobophora chlorotica were significantly greater. Copyright © 1979, Wiley Blackwell. All rights reserved