EFFECTS ON EARTHWORM POPULATIONS OF REDUCING PESTICIDE USE IN ARABLE CROP ROTATIONS

The SCARAB project is a held-scale, six-year investigation of the effe cts of pesticide use on invertebrates and soil microflora in arable cr op systems common in the U.K. Two pesticide regimes are being compared : current farm practice (CFP) which represents typical levels of use i n the study localities, and reduced input approach (RIA) in which inpu ts have been reduced by 50% and no insecticides used. The treatments b egan at three farms in 1990, and effects on earthworm populations have been monitored twice yearly since Spring 1993. Particular attention w as paid to age and species composition. Results up to Spring 1994 show ed that although some differences existed between earthworm population s in RIA and CFP plots they lacked consistency over time and between t he pairs of plots, and were of negligible magnitude compared with over all differences between the farms. It was concluded that the two pesti cide regimes caused no ecologically significant differences in earthwo rm populations at this stage of the project. The substantial differenc es in earthworm populations between farms were largely consistent with the expected effects of differences in climate, soil types, crop type s, cultivations and pesticide use, although the relative importance of these factors can not yet be assessed. Crown Copyright (C) 1997 Publi shed by Elsevier Science Ltd.