Response of Yields and Yield Variability of Wheat and Barley to Nitrogen Fertilizing and Fungicide Treatments

Abstract

AbstractFrom the results of a long term experiment with wheat and barley and different fungicide treatments it could be concluded that the variability of yield did not increase with higher application rates of nitrogen until the maximum yield was reached. The relative variability even decreased due to the increasing yields and the nearly constant standard deviations of yields. Only if the fertilization exceeded the optimum and yield depressions occurred the yield variability increased especially for barley and on plots without fungicide treatments. Whether the yield variability increases with increasing intensity or not depends on the factors of intensification and whether these factors increase the yield potential (higher yielding varieties for example) or whether they only realize more of a given potential (like higher amounts of nitrogen). In the first case yield variability will increase while in the second a higher yield stability has to be expected. The changes in yield variability within time series raise from both factors and, therefore, the individual situation may be very different from one country to another and may also change within a country with time.