[The effect of chronic UVB-radiation on the nitrogen-fixing capability of soils in a field experiment]

The effect of chronic UV-B-irradiation on the nitrogen-fixing ability of soil was studied in a field experiment. In the study, LER-40 lamps were used as a source of additional UV-B-irradiation with respect to natural illumination (the irradiation level = 0.34, 0.49 and 0.77 W/m2). Nitrogen-fixation was measured by gas chromatography. The experimental results were treated by bifactorial analysis of variance. It was found that chronic UV-B-irradiation affected the nitrogen-fixing ability of soil during the observation period (June-August). At soil UV-B-irradiation of 0.34 and 0.49 W/m2 the nitrogen-fixation intensity increased by 17 and 9%, respectively, and at soil UV-B-irradiation of 0.77 W/m2 it decreased by 13%, when compared to untreated controls.