Reducing intra-row weed numbers in row crops by means of a biennial cultivation system

Summary

Intra-row weed emergence in row crops can be reduced by means of a biennial cultivation system that is based on an exhaustion of the weed seedbank in the upper soil layer of crop-free bands established in a preceding cereal crop, year I, prior to the row crop, year II. In this study, a series of field experiments is presented focussing more specifically on the influence of prevention of weed seed shedding and of different cultivation tactics in the system on intra-row weed emergence in the bands in year II. As the system excludes inverting soil tillage between year I and year II, the prevention of weed seed shedding in year I turned out to be a key factor for achieving the desired effect of the system. This was seen with spring barley grown in year I but not with winter wheat, where the system actually resulted in an increase of intra-row weed numbers in spite of the measures taken in year I. Cultivating the crop-free bands in spring barley in year I with conventional goose-foot shares in order to further enhance seed germination and mortality had no significant effects regardless of time and intensity. Results from two other experiments, where freshly shed weed seeds were incorporated into the soil, supported the finding that cultivating the bands was of no advantage.