Earthworm activity improves soil fertility. In arable crop rotations highest earthworm populations are usually found in leys. The impact of tillage system and tillage intensity on earthworm populations was studied in the two long term trials at Burgrain (Albertswil LU) and at Hausweid (Aadorf TG). At Burgrain having a crop rotation lasting six years and including a ley, no significant difference of earthworm biomass was found between ploughed plots and plots with in the sampling period 2004-2008 in the tillage system using minimum tillage (mulch drilling for oilseed rape and sowing with a rotary band cultivator rotary band seeding for silage maize) (IP extensive) compared to ploughing in both, the organic as well as the integrated production (IP intensive). In contrast, at Hausweid having a four years crop rotation at Hausweid without ley, earthworm populations differed significantly depending on tillage system and tillage intensity after 21 years of the trial. Earthworm biomass reached 330 g per m 2 in the permanent grassland adjacent to the trial whereas it was reduced by 50% in the no-till and even by 80% in the ploughed plots. Additionally, average earthworm species diversity in permanent grassland and no-till was 30% higher than in ploughed tillage system. These findings confirm the positive impact of no-till on the increase of earthworm populations and species diversity.
