(Unit/t of production)
(Unit/t of production)
500-1000g/ha boron (B), splitted and combined with pesticides in autumn and spring; 15-25g/ha molybdenum (Mo)
The right fertilization strategy:
Rapeseed needs its nutrients in stages. Therefore, it is recommended to split it into at least three applications. A strong root system, optimal, not too vigorous autumn growth (>1cm root neck diameter and 8-12 leaves), uninterrupted and lush spring growth between shoots and the beginning of flowering, and a harmonious nutrient- and water supply from the beginning of flowering to the end of maturity are important yield determining factors.
The yield parameters of rapeseed:
Autumn fertilization - the most important fertilization
Rapeseed already needs a third of its nutrients in autumn. Factors that determine a good yield (flowers on the side shoots) are already created in autumn. Ideally, the plant consists of 8-12 leaves before the dormant period and has a strong tap root (>1cm root neck diameter). The tap root is functionally important for regeneration in spring, to start growth as soon as possible. Good winter hardiness is ensured by a sufficient supply of potassium. Rapeseed can also be fertilized in autumn with nitrogen, regardless of the preceding crop and sowing date. If some crop residue from the harvest of the preceding crop has not yet been decomposed, the soil is often not able to supply enough nitrogen. Too much nitrogen can cause the stock to grow too much, which leads to a lifting of the vegetation cone (meristem) of the plant and thus to a massive reduction in winter hardiness.
First application in spring
Second application in spring
Fertilization in spring at the beginning of the growth period:
The first dose at the beginning of the growth period is used for the regeneration of the leaf rosette and promotes the already formed leaf and blossom plants on the vegetation cone (meristem). In addition to the formation of flower buds on the side shoots, it supports the growth in length of the main shoot and the subsequent branching of the plants. A combined fertilization of nitrogen and sulphur yields more than nitrogen alone. Underdeveloped stocks with less than six leaves require enhanced fertilization, while more highly developed plants will have already taken in more nutrients in the autumn and are therefore fertilized less. A stock of 30 plants/m², with 12 leaves and a root neck diameter of 15mm, will have already absorbed 100-130kg N/ha, while plants with eight leaves and 10mm root neck thicknesses will have absorbed about 40-50kg N/ha at the same stock density. In underdeveloped stocks, 80-100kg N/ha are appropriate while well-developed stocks should receive at least 50-70kg N/ha as a starting dose.
Dose at the beginning of bolting:
The second and last spring fertilization should take place end of March. This promotes the growth in length of the side shoots. It ensures a supply of nitrogen to the flower, ensures fruiting and the attainment of a high pod and seed count. Until flowering, rapeseed stock absorbs about 75% of the total nitrogen. As no appreciable replenishment can be expected with the still low soil temperatures, the second dose should be given in time before the emergence of the flower buds. The plants will now be 15-25cm tall. The level of the last nitrogen fertilization depends on the amount administered previously. Stocks that have developed sufficiently over the winter and are therefore only slightly fertilized, receive most of their nitrogen in the spring in the second dose. However, underdeveloped or late-fertilized stocks receive about 2/3 of the N amount in the spring in the first and 1/3 of the N amount in the second dose. A sufficient supply of potassium is of great importance here, the plants now take up to 7kg/ha potassium daily.