Effect of tillage methods on soil erosion in Norway.

摘要

Soil erosion is considered a serious environmental problem in parts of Norway. The effect on water quality is the most important concern, and the improvement of water quality is the major aim for mitigation techniques and regulations on tillage. Documentation of effects of tillage practices therefore has a high priority. In this paper, results from five plot experiments are presented. They are all located in the grain-growing district in southeastern Norway on clay and loam soils. Tillage treatments for spring cereals and winter cereals are compared. The effect of tillage is pronounced on erodible soils. The results showed that annual average soil losses in surface runoff for autumn-tilled and spring-tilled plots were 7 and 0.8 t ha-1yr-1 at Bjornebekk; 4.3 and 0.4 t ha-1yr-1 at Askim; 2.6 and 0.2 t ha-1yr-1 at Hellerud; 1.1 and 0.2 t ha-1yr-1 at Osaker; and 0.18 and 0.1 t ha-1yr-1 at Syverud, respectively. The corresponding total phosphorus losses were 8.4 and 1.5 kg ha-1yr-1 at Bjornebekk; 4.5 and 0.8 kg ha-1yr-1 at Askim; 3.0 and 0.8 kg ha-1yr-1 at Hellerud; 1.30 and 0.44 kg ha-1yr-1 at Osaker; and 0.43 and 0.45 kg ha-1yr-1 at Syverud for autumn and spring tillage, respectively. The effects were less pronounced on soils with a lower erodibility, but reduced autumn tillage is the most effective way to mitigate soil erosion as well as total phosphorus losses. The study also showed that the total phosphorus losses are closely correlated with soil losses. The results show the importance of soil tillage for soil and phosphorus losses and suggest that farmers avoid autumn tillage on areas with high erosion risk.