Effect of boron and cadmium on nitrogen fixation in soil

The influence of different doses of boron (100, 500 and 1000 ppm) and cadmium (50, 100, 500, 1000 and 2000 ppm) on the activity of nitrogen fixation in the sandy and alluvial soil has been studied. Almost all doses of boron stimulated this process except 1000 ppm of B added to the sandy soil. All the doses of cadmium also exerted a positive effect on the nitrogen fixation, but only during the first 3 months of the experiment, later (after 12 months) Cd decreased the activity of this process. The most marked effect to the examined elements was pronounced in the sandy soil.