Conservation tillage is often discussed as an effective tool to improve the soil quality in agriculture. Four sites across Europe (in Germany, Romania, Spain, and Sweden) were investigated as case studies for country-specific reductions in tillage intensity. Conventional tillage (CT) by mouldboard ploughing was compared with shallow and deep non-inversion minimum tillage (MT) and/or no-tillage (NT). In Sweden, NT and MT had positive effects on the concentrations of soil organic carbon (SOC), total nitrogen (N), and microbial biomass carbon (MBC) in the upper 20 cm compared with CT. At the German site, MT increased SOC, N, and MBC concentrations in the top 10 cm. In contrast, CT increased MBC contents and bulk density between 20 and 30 cm soil depth. At the Romanian site, soil parameters showed no differences between inverse tillage (CT) and non-inverse tillage (MT), both with a working depth of 25 to 30 cm. At the Spanish site, the use of NT significantly increased the concentrations as well as the stocks of C, N, and MBC compared to CT. In conclusion, reduced tillage improved soil microbial properties in most cases. However, the effectiveness of reduced tillage appears to be highly dependent on site conditions such as pH, soil texture, and climatic conditions.
Keywords: microbial biomass; minimum tillage; mouldboard ploughing; no-tillage; soil quality.