Yield development of winter wheat over 50 years of FYM, N, P and K fertilizer application on black earth soil in the Czech Republic

The black earths of Central Europe are an important soils for crop production but sustainability of crop production on such soils has not been examined. In the present paper, yield of winter wheat over 50 years of FYM, N, P and K fertilizer application (12 treatments altogether) was analyzed in the Ivanovice Crop Rotation Experiment (ICRE), established in 1955 on a degraded black earth soil (chernozem). The ICRE is located in a warm (8.4 degrees C mean annual temperature) and moderately dry (556 mm mean annual precipitation) sugar beet cropping area. Summarizing 50 years' results, variety had the largest effect on grain yield followed by the effect of mineral fertilizers, the preceding crop and farmyard manure application. The highest increase in grain yields was recorded after the introduction of short-straw varieties. High year-to-year variability in grain yields was recorded and some fluctuations were consistent with oscillations in the whole Czech Republic. Despite the high fertility of black earth soils in the locality, the mean grain yield in the ICRE was lower than the mean annual yield in the Czech Republic in five cases out of 50 years. The effect of fertilizer treatment on the grain yield was not significant in the first decade (the mean grain yields ranged from 3.4 to 3.8 t ha(-1)), but was significant in the fifth decade of the experiment (the mean grain yields ranged from 4.2 in control to 6.6 t ha(-1) in N121P89K102 treatment, respectively). Calculated by linear regression, the annual yield increased by 45.9-89.6 kg of grain per ha. The mean yield per I kg of applied N ha(-1) increased by 18.7 kg of grain in the fifth decade of the experiment. In unfertilized soil, the concentration of plant-available P, K and Mg was still optimal for winter wheat production even after 50 years without any fertilizer input. The black earth soils in the locality clearly demonstrates a high and long-term stable natural fertility. The results from the ICRE stress the necessity for long-term research in grain yield analysis. (C) 2008 Elsevier B.V. All rights reserved.