Abstract - Six cropping systems, ranging from conventional arable without livestock to organic livestock farming dominated by ley, have been compared since 1990 in SE Norway. Earthworm density (ED), earthworm biomass (EB), channel density (CD) and species of worms were measured in the topsoil (0-25 cm) in 1994 and 2004. Ley in the crop rotation increased EB, ED and CD in both organic and conventional systems, but a ley proportion higher than 25 % only increased CD. Among the arable systems, the organic system hosted more individuals (ED) and a higher biomass (EB) of earthworms as compared to the conventional systems. The conventional arable systems had low values in 2004, and only minor changes in EB and ED during the period compared with the other systems. The earthworm species observed were field worm (Aporrectodea caliginosa), pink worm (A. rosea) and night crawlers (Lumbricus terrestris)
