Open access publications in the SLU publication database

Abstract

Nitrogen leaching during autumn and winter after establishment of winter oil-seed rape (Brassica napus L.) in Sweden is usually relatively high. The reasons are most likely the tillage operations that need to be carried out in summer and the common use of fertilizer nitrogen at establishment. To reduce these negative effects of tillage and fertilizers when growing winter rape, the possibility to establish Winter rape by direct drilling into growing ryegrass (Lolium perenne L.) or white clover (Trifolium repens L.) was evaluated in a field experiment at Lönnstorp, Skåne. On a morainic clay loam, autumn mould board ploughing followed by conventional seedbed preparation and sowing was compared with direct drilling into barley stubble, and with direct drilling into the growing catch crop, previously established in spring barley (Hordeum vulgare L.). Throughout the experiment, 48 cm row spacing was used for the rape. The tillage treatments were combined with nitrogen fertilizer strategies, with or without 40 kg N ha-1 in autumn at establishment. Where nitrogen was added in the autumn, the amount of fertilizer added in spring was reduced with the same amount. In spring, only the treatments without a catch crop were inter-row weeded because of too vigorously developed ryegrass and white clover, and weeding was therefore not possible to carry out in these treatments. Direct drilling of winter rape was successful compared to conventional tillage, even though the mean root neck diameter of oil seed rape in November was small and the over-wintering was poor There was no yield of oil seed rape when it was sown into growing ryegrass due to poor establishment of the rape and poor overwintering. In the direct drilled treatment, the yield was 11 % higher with autumn fertilizer than without. Tillage strategies for establishing catch crops and main crops in catch crop production systems need to be further developed to be of practical use in agricultural production.