Utilisation of the long‐term field experiments in Prague‐ Ruzyne in modern agricultural research

Abstract

The data collected during 27 years (1968–1994) have been used for the evaluation of the production function, regulatory function, and also partly for the evaluation of the biotop and transformation functions of soil in the long‐term field experiment in Prague‐Ruzyne. The average dry matter yields in the fertilised variants in block B were higher than those in block IV, mainly due to the high frequency of sugar beet in the rotation. However, this simple crop rotation cannot be considered as a sustainable one from the production point of view. Classical crop rotation, on the other hand, is sustainable, particularly in the variants manured by farmyard manure. The changes in organic carbon in soil were small over the period of 27 years. They were positive (increasing) in all the selected variants and thus sustainable from the point of view of the transformation function of soil. Carbon balance was positive in all the selected variants. The highest values were found in NPK. variants, indicating a positive effect of mineral fertilisation on the carbon sequestration to soil. Average nitrogen uptake in the nil variant in block B (without legumes) was 66 kg N.lbha^‐1, which is approximately the atmospheric nitrogen deposition in this site. The highest values of the nitrogen balance were found on the nil plots, in which the least nitrogen losses can be expected. Increasing nitrogen input caused lower values of the nitrogen balance, probably due to increasing nitrogen losses. There are no remarkable differences between the effect of organic and mineral fertilisers on the nitrogen balance. The average nitrogen fixation under lucerne stand can be estimated to 189 kgN .lb ha^‐1.lby^‐1 in the nil plot.