Yield Reaction of Winter Wheat in Monoculture in Dependence upon Weather and Soil

On the basis of a long-term field experiment with a progessive monoculture of wheat carried out on the research station Hohenschulen (University of Kiel), the yield reaction of wheat in monoculture was analysed with help of a multiple regression approach.
The mean yield of several years declines till the third resp. fourth crop, it increases later ('decline-effect' in the larger sense) without reaching the initial level however.
The weather considerably influence the absolute yield level as well as the yield trend in dependence upon the number of successive wheat crops. Interactions between yield and soil conditions are only slightly marked if the absolute yield is considered. The yield components, however, react differently according to the soil conditions.
Crop management measures such as the choice of varieties and the application of BCM-fungicides or N-fertilization were only able to reduce yield losses, but not to prevent them.