The modern rapeseed hybrids have a high potential of yield, but the realization depends – beside the weather and the proper soil – also in 30-40% on the plant nutrition. Therefore it is worth to consider the autumn fertilization.
Due to the extra long vegetation period and the huge biomass the rapeseed takes up a high amount of nutrients, which has to be provided by both the soil and the fertilizers. The amount of nutrients what the plant needs for its growths is much higher, as what is taken away with the yield.
The table shows both the nutrient uptake by the plant and the extraction per tonne of grain yield. Rapeseed is extremely sensitive to nitrogen, potassium and sulphur deficiency; however, phosphorus and magnesium also play an important role. For example: A rapeseed yield of 4 t/ha absorbs a total of 280 kg N/ha. If 80 kg N/ha is provided from the soil, then another 200kg N/ha would need to be added as fertilizer. The harvested grain would extract 172 kg N/ha from the field.
The basis for a successful rapeseed production is to use a high quality NPK fertilizer as basic application, as it ensures in comparison to fertilization just with N a relevant yield increase. The dosis of the NPK is determined by the nitrogen: more than 30-40 kg N/ha should not be applied. As earlier we sow the rape, as less nitrogen we should give, so we can control the autumn development, and the crops will be not overdeveloped before winter. Phosphate in autumn is also essential: it is needed for compounds to build up cells, therefore it is key in the early development, especially regarding root growing. P also increases the number of side shoots, fertility and supports seed development, so contributes to oil content. Potassium supports the water usage efficiency of the plants, and so the stress tolerance.
Rapeseed also needs sulphur, which has an important role in the oil production. The lack of S can already appear in autumn, so it is important to give already enough S in the beginning. Some NPK fetilizers contain also S, and additional N+S fertilizers in spring can contribute to cover the need of 30-40 kg/ha S-demand of the rapeseed.
Rapeseed shows an extreme good nutrition reaction: intensive fertilization result in significant yield and oil content increase, as our field trials also show. The fertilization with NPK in autumn, N+S and CAN in spring and autumn-spring foliar fertilization resulted 740 kg/ha yield increase in the average of our Hungarian trials.
For the autumn basic fertilization of rapeseed Borealis L.A.T recommends the following cost-effective, high quality products, which contain the nutrients mostly in water soluble form: COMPLEX 15/15/15 +7SO3 and COMPLEX 14/10/20+10SO3.
If plants get all necessary nutrients already in autumn, a well-developed and strong rooted plant stock faces the winter, which is already a milestone on the way to a good yield.