On-farm study of reduced tillage on sandy soil: effects on soil organic carbon dynamic and earthworm abundance

Information about the long-term effects of reduced soil tillage on soil fertility of sandy soils under dry climatic conditions is scarce. Soil organic carbon and earthworm populations were evaluated as soil fertility indicators in an on-farm study between 1996 and 2008. The study comprised adjacent conventional and reduced tillage treatments, undertaken at field (74 ha) scale in Northeast Brandenburg, Germany, with a total of 42 plots on heterogeneous sandy loam. The soil is classified as a Luvisol. Organic carbon stocks at 0–30 cm depth increased between 1996 and 2008 in both tillage systems. This increase corresponded to predictions obtained with the humus balance method based on crop rotation and yields. Increases of organic carbon stocks were slightly more pronounced in plots under reduced tillage. Earthworm population numbers determined by handsorting at 42 plots, were higher in plots under reduced tillage compared to conventional tillage, mainly due to the occurrence of Lumbricus terrestris. The res...