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Abstract: In this study, the performance of nine widely used and accessible crop growth simulation models (APES-ACE, CROPSYST, DAISY, DSSAT-CERES, FASSET, HERMES, MONICA, STICS and WOFOST) was compared during 44 growing seasons of spring barley (Hordeum vulgare L.) at seven sites in Northern and Central Europe. The aims of this model comparison were to examine how different process-based crop models perform at multiple sites across Europe when applied with minimal information for model calibration of spring barley at field scale, whether individual models perform better than the multi-model mean, and what the uncertainty ranges are in simulated grain yields. The reasons for differences among the models and how results for barley compare to winter wheat are discussed. Regarding yield estimation, best performing based on the root mean square error (RMSE) were models HERMES, MONICA and WOFOST with lowest values of 1124, 1282 and 1325 (kgha−1), respectively. Applying the index of agreement (IA), models WOFOST, DAISY and HERMES scored best having highest values (0.632, 0.631 and 0.585, respectively). Most models systematically underestimated yields, whereby CROPSYST showed the highest deviation as indicated by the mean bias error (MBE) (−1159kgha−1). While the wide range of simulated yields across all sites and years shows the high uncertainties in model estimates with only restricted calibration, mean predictions from the nine models agreed well with observations. Results of this paper also show that models that were more accurate in predicting phenology were not necessarily the ones better estimating grain yields. Total above-ground biomass estimates often did not follow the patterns of grain yield estimates and, thus, harvest indices were also different. Estimates of soil moisture dynamics varied greatly. In comparison, even though the growing cycle for winter wheat is several months longer than for spring barley, using RMSE and IA as indicators, models performed slightly, but not significantly, better in predicting wheat yields. Errors in reproducing crop phenology were similar, which in conjunction with the shorter growth cycle of barley has higher effects on accuracy in yield prediction. [Copyright &y& Elsevier]

Abstract: Although Cambisols are the predominant soil type in Central Europe, especially in less favoured mountain areas, the long-term sustainability of winter wheat production on such soils has not been examined. In this paper, the yield of winter wheat over 50 years of farmyard manure, N, P and K fertilizer application (12 treatments altogether) was analysed in the Lukavec Crop Rotation Experiment (LCRE), which was established in 1955 in a potato-growing area (mean annual precipitation and temperature 686mm and 6.8°C, respectively). In the unfertilized control, low plant available P, K and Mg concentrations were recorded after 50 years. The annual yield growth (AYG) of grain was negative in the control as well as in low N treatments and positive in the 46kgNha−1 treatment. The mean AYG ranged from 7.1 to 72.8kgha−1 following the application of 46 to 121kgNha−1, respectively. In the first decade of the experiment, the increase in grain yield per 1kg of applied N was 7.3kgha−1 while in the last decade it was 27.1kgha−1. The mean grain yield of long-straw and short-straw varieties was 3.9 and 4.7tha−1, respectively. In the control, the grain yields were 4.3, 3.2 and 2.4tha−1 after root crops, legumes and cereals, respectively. To summarize the 50 years’ results of winter wheat production in the LCRE, grain yield was the most affected by mineral fertilizers, followed by the effect of variety, the preceding crop and farmyard manure application. The long-term sustainability of winter wheat production on low productive sandy-loamy Cambisols can be achieved only by adequate application of N, P and K fertilizers. High year-to-year variation in grain yield stresses the necessity of long-term studies in crop research, which are able to separate real trends from inter-annual fluctuations. [Copyright &y& Elsevier]

Abstract: 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°C mean annual temperature) and moderately dry (556mm 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 3.8tha−1), but was significant in the fifth decade of the experiment (the mean grain yields ranged from 4.2 in control to 6.6tha−1 in N121P89K102 treatment, respectively). Calculated by linear regression, the annual yield increased by 45.9–89.6kg of grain per ha. The mean yield per 1kg of applied Nha−1 increased by 18.7kg 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. [Copyright &y& Elsevier]