EFFECT OF ECOLOGICAL FACTORS ON RHIZOBIAL SPREADING AND NITROGEN-FIXING ACTIVITIES IN HUNGARIAN SOIL TYPES

The success in nitrogen-fixation ability of legumes (alfalfa, pea, fab abean, soybean) is influenced by numerous biotic and abiotic factors. In soils of different chemical, physical and biological properties, an d under different climatic conditions, the Rhizobium inoculation effic iency is very different, as well. The soybean test plant showed the be st 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 small est activity, related to the Rhizobium population occurred spontaneous ly in soil. By additional PK fertilization together with Rhizobium-ino culation, the crop yield and nitrogen content values have been increas ed in a great per cent, at the same time, the nodule number and Acetyl ene 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 v alues. As for soils, positive inoculation effect was obtained in the g reatest per cent in case of brown forest and chernozem soils.