Evaluation of the interaction between nutrient supply and water management on the basis of a long-term experiment in Debrecen

Abstract

The high degree of climate variability is one of the greatest risk factors for agricultural production, which needs to be taken into consideration at all times, even within the framework of modern agriculture.One of the most important ways of adapting to changing climatic conditions is to analyse varieties and genotypes with relatively good climatic adaptation in terms of yield potential and growing requirements.The effect of year on the yield of maize was examined using a twenty-four year yield sequence. The weather was extremely variable in the examined period, so the effect of fertilisation also differed greatly. There was a clear correlation between the quantity of precipitation in the winter period and in the growing season and the yield of unfertilised treatments. The quantitative relationship between the two variables was moderate, because not only the total quantity of precipitation, but also the distribution over time has a significant influence on the yield. Very low yields were not always associated with the lowest precipitation sums (1994, 1995). Larger yields, however, were only achieved with higher precipitation (1980, 1998, 1999, 2001, 2004, 2005, 2008). It can be clearly seen that similar precipitation quantities resulted in different yield levels, due to the distribution of precipitation over time. The available water in the soil profile in spring is decisively influenced by precipitation during the winter period. An analysis of the results revealed a close correlation between the years and the fertilisation rate. In dry years a lower rate of fertilisation was more favourable, while in years with average or above-average precipitation, higher rates led to better yields. Under droughty conditions, and especially in consecutive dry years, the application of not more than 60 kg N ha −1 fertiliser is recommended, as higher fertiliser rates (1995) increase the risk level of maize production, thus reducing the efficiency. In the case of favourable water supplies, experimental results suggest that the application of 120 kg N ha −1 is justified. The results of analysis of variance indicated that the fertiliser effect was significant when averaged over the twenty-four years, but when the years were evaluated separately, the effect was found to differ, depending on the water supplies.The yield of the maize hybrids was 10 t ha −1 in years with favourable water supplies, but only 2–4 t ha −1 in droughty years. Yield fluctuations can be reduced through appropriate soil cultivation, water and nutrient supplies.