Effect of ecological factors on rhizobial spreading and nitrogen-fixing activities in Hungarian soil types

Summary The success in nitrogen-fixation ability of legumes (alfalfa, pea, fababean, soybean) is influenced by numerous biotic and abiotic factors. In soils of different chemical, physical and biological properties, and under different climatic conditions, the Rhizobium inoculation efficiency is very different, as well. The soybean test plant showed the best inoculation effectivenes, succeeding by the fababean, and the least positive effect was observed — in accordance with the literature — in the alfalfa and pea plants. Hence, the soybean plant showed the smallest activity, related to the Rhizobium population occurred spontaneously in soil. By additional PK fertilization together with Rhizobium -inoculation, the crop yield and nitrogen content values have been increased in a great per cent, at the same time, the nodule number and Acetylene Reduction Activity (ARA) values were not increased significantly, compared to the non-fertilized variants. According to our observations, the inoculation efficiency was negatively influenced by the low PK values. As for soils, positive inoculation effect was obtained in the greatest per cent in case of brown forest and chernozem soils.