Soil biology after ten years of no- and conventional tillage

Over the last ten years, conventional plow tillage has been compared to no-tillage in the long-term field trial “Oberacker” at the Inforama Ruetti in Zollikofen. Earthworm populations, microbial biomass and soil respiration have been monitored since 1998-99. The average earthworm biomass is 94 g/m2 on conventionally tilled plots and 190 g/m2 on no-tilled plots. Deep-burrowers, which are important for soil drainage, form 25% of this biomass in conventional tillage and more than 50% in the long-standing no-tillage fields, the latter comprising especially of the species L. terrestris. Intensive tillage reduces the occurrence of larger species and their permanent burrows. Under no-tillage cultivation and in the absence of potatoes in the crop rotation, total earthworm biomass and the proportion of deep-burrowers are comparable to those in a natural meadow. The microbiological parameters, microbial biomass and soil respiration, showed only slight system-induced differences in their distribution between depth layers.In the absence of tillage operations the conditions for organic matter degradation are altered. Plant residues gathering on the soil surface is fast decomposed due to efficient mixing by the large earthworm population in collaboration with microbial activity, thus preventing the spread of plant disease.