Tillage treatments and earthworm distribution in a swiss experimental corn field

Abstract

A pedobiological investigation was performed on a soil erosion research area of the Geographical Institute of the University of Basel from April to November 1989. The site belongs to, and is cultivated by, the Agricultural School Centre “Kantonale Landwirtschaftliche Schule” Stickhof/Eschikon in Lindau near Zürich (northern Switzerland). In a cropping experiment with corn ( Zea mays), the influence of four tillage systems on earthworm populations was studied. Aspects of soil physics and soil chemistry were integrated into the investigation. The earthworms were extracted by means of the hand sorting method at six dates in 1989 chosen to represent typical periods of corn cropping. The four tested tillage systems had an influence on earthworm species composition, abundance, and biomass: (1) The consequence of tillage itself was a reduction of about 50% of abundance (number of individuals m −2) and 30% of biomass (g live w m −2), but these losses were equalized during the following months. (2) The minimum tillage (strip zone tillage with a rotary cultivator and simultaneous seeding) caused a higher soil compaction, a negative selection of horizontally burrowing (“endogé”) species, and a subsequent diminution of their abundance. (3) Ploughing had a disadvantageous effect on vertically burrowing (“anecique”) species. (4) The winter catch crop cover enhanced the food supply and hence the earthworm biomass. An undersown cover had an additional favourable effect on earthworms.