Effect of reduced herbicide amounts with minimum tillage systems on weed infestation

Minimum tillage, mainly soil cultivation without ploughing is used in Germany on 40% of arable land. In a long-term field trial in Dahnsdorf (federal state of Brandenburg, Germany) the impact of reduced tillage on weed occurrence is investigated. At the same time reduced herbicide amounts are also tested. The use of glyphosate for seedbed preparation is not always necessary. The former crop rotation (67% cereals or 50% cereals) has even seven years later a big influence on the weed occurrence. The weed occurrences are lower for the crop rotation with the former 50% cereals. After four years the minimum tillage shows a larger effect of weed infestation. For the non ploughed variants it is higher. If reduced herbicide amounts are used at the same time the effect will increase even more. Results for Apera spica-venti are similar, although the conditions for germination in autumn are also relevant