Fertiliser responses of maize and winter wheat as a function of year and forecrop

The N, P and K effects of mineral fertilisers were examined in a long-term fertilisation experiment set up on chernozem soil with forest residues. The data from 20 experiments on winter wheat and 24 on maize were evaluated as a function of the year, the forecrop and the soil nutrient supplies.Of the two plant species, N effects were found to be greater for winter wheat. When sown after maize, the N responses of both wheat and maize were almost 1 t ha −1 greater than when winter wheat was the forecrop. The positive effect of phosphorus was only significant in winter wheat, while that of potassium was not significant for either species.In a wheat-wheat sequence, N fertiliser alone was only effective in wet years. In winter wheat, no phosphorus effects could be detected in any year without N fertilisation. In years with extreme weather conditions, P effects were only significant when wheat was grown after cereals.In dry years nitrogen only had a significant effect on the yield of maize after wheat if it was combined with phosphorus and potassium. In years with average or above-average rainfall maize was able to extract sufficient phosphorus for its development even from soils with poor P supplies; yield increases were limited by other factors.