Effect of Azotobacter inoculation on plant growth and soil nitrogen.

The validity of seed bacterization with Azotobacter chroococcum in soils of variable densities of naturally present azotobacters was studied. Inoculation of barley grains had no effect on counts of total microflora, neither in rhizosphere nor in root-free soil, but significantly increased Azotobacter population, especially in the rhizosphere. The rate of colonization in the root region was much higher when soil initially harboured low Azotobacter densities. Bacterization improved plant growth and increased soil nitrogen through nitrogen fixation. Nitrogen balance in soils showed higher gains in the inoculated treatments over the uninoculated analogues of 30--98 ppm.