Modern varieties of winter rapeseed require a lot of nitrogen in early spring. In cool, moist and dry soils, the N mineralisation can be inhibited, which leads to an insufficient N supply and yield losses.
Fast releasing fertilizer application in autumn and spring can perfectly complement the basic fertilisation (applied via crop rotation and manure before sowing) and prevent a lack of nitrogen in spring.
Optimal fertilisation ensures that the current rapeseed varieties and reach their full yield potential.
• In conventional cultivation, the nitrogen uptake of winter oilseed rape amounts to 140 kg N per ha for a yield expectation of 35 dt per ha. In organic agriculture, about 100 kg suffice for a yield expectation of 20-25 dt.
• The ideal time for cultivating oilseed rape is after grass-clover or legumes. After grains, apply about 30 tonnes per ha of manure or manure compost before cultivating rapeseed.
• In dry conditions in spring, an early single application of nitrogen is preferable to two smaller applications. In the case of slurry with a low N content, two applications are often required because maximum of 40 m3 of slurry can be applied at once. Regularly analyse the N content of slurry (regular content: 1 kg of N per m3 of slurry or tonne of manure, respectively; range: 0, 3 kg N per m3 for cow slurry to 3 kg N per m3 for pig slurry). The N contents of commercial fertiliser and liquid digestate are disclosed by the suppliers.
• On farms without livestock, one dose of organic commercial fertiliser is applied in early spring.