摘要：Sulphur plays an important role in metabolism of all living organisms influencing their proper growth and development, and its role in the nitrogen fixation process by nodule bacteria has been already pointed out by many authors. According to the Washington World Institute of Sulphur, there is a real risk of soil sulphur deficiency, which could be a limiting factor of the global food safety. Positive interaction of sulphur with potassium was previously noted in relation to higher plant growth and development. However, there is still lack of investigations concerning on effects of various sulphur and potassium fertilisation on nitrogenase activity of Fabaceae plants, like broad bean. The aim of the present study was to assess the effects of increasing potassium and sulphur fertilisation in a broad bean culture on the variability in the microbial composition of soil, i.e. total number of bacteria, fungi, actinobacteria, oligotrophs and copiotrophs, as well as the enzymatic activity of dehydrogenases, acid phosphatase and nitrogenase of bacteria in symbiosis with the broad bean. Potassium fertilisation increased the number of soil microorganisms; however, supplementary sulphur fertilisation did not promote development of microorganisms. Applied fertilisation resulted in increasing enzymatic activity of dehydrogenases, while that of acid phosphatase was lower, when potassium fertilisation was applied at 80 and 160 kg ha-1 and sulphur fertilisation at 25 and 50 kg·ha-1. An enhance in nitrogenase activity was observed at increasing levels of sulphur fertilisation and the absence of potassium fertilisation, as well as under the opposite fertilisation scheme whereas potassium fertilisation with higher sulphur doses caused reduction of nitrogenase activity.
关键词：Broad bean; sulphur and potassium fertilisation; soil;
nitrogenase and microbial activity
