Phosphorus and potassium fertilization is based on offtake created by the harvest.
Organic fertilization, biological nitrogen fixation, and organic matter provide significant amounts of nitrogen.
Sulphur increases the efficiency of nitrogen fertilization.
The withdrawal of calcium and magnesium has to be replaced through fertilization.
Next to biological nitrogen fixation by the legumes, the cultivation of forage has other positive effects on the soil, for example it is a superb crop for the suppression of weeds. In order to optimize the fixed nitrogen, the forage crop must be destroyed in spring in allowing the succeeding crop to access it. Weeds such as creeping thistle and black grass do not tolerate multiple cuts. Other weeds are reduced due to the permanent soil cover. The intensive root system improves the crumb structure of the soil, mobilizes nutrients and increases soil organic matter.
The protein content of grasses is with 12 to 15% lower than that of legumes (25% protein in lucerne). The mixing ratio of grasses and legumes determines the protein content of the harvest. Legumes are more competitive during the warm summer months and increase their relative mass. Fertilization with nitrogen increases the competitiveness of grass and facilitates a stable grass/legumes ratio.