Influence of Ultraviolet Radiation on Microbiological Activity of Sod-Podzolic Soil

In a series of model experiments, the effects of ultraviolet radiation on the soil microflora and some agrochemical parameters of the arable layer of sod-podzolic soil (Albic Glossic Retisol) of Republic of Mari El were studied. A 30-UVC bactericidal lamp was used for irradiation in a laboratory installation. The exposure time was 50 hours. Soil incubation was carried out at an optimal temperature and humidity (25°C, 60% full field moisture capacity) for 14 days. Agrochemical analyses of the soil were carried out using generally accepted methods. The number of the main ecological and trophic groups of microorganisms was determined by sowing various soil dilutions on agarized nutrient media. It was found that under the influence of ultraviolet radiation, the amount of mineral and easily hydrolyzable nitrogen in the soil increased, which indicated the photochemical destruction of humus and the formation of more mobile humic substances capable of leaching. A short-term decrease in the number of microflora involved in the mineralization of carbonand nitrogen-containing organic matter was revealed under the influence of ultraviolet radiation. At the same time, the sensitivity of microorganisms to ultraviolet radiation was as follows: spore-forming bacteria < actinomycetes < azotobacter < amylolytics < ammonifiers < micromycetes < nitrifiers. The change in the orientation of the transformation processes of organic matter towards the activation of mineralization processes and an increase in the provision of microorganisms with readily available nutrients is shown.