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

A series of model experiments were used to investigate the effect of ultraviolet radiation on soil microflora and some agrochemical indicators of the plow layer of sod-podzolic soil (Albic Glossic Retisol) in the Republic of Mari El. A 30-UVC bactericidal lamp was used for irradiation in a laboratory setup, with an exposure time of 50 h, followed by soil incubation at optimal temperature and humidity (25°C, 60% WHC) for 14 days. Agrochemical analysis was carried out using traditional methods in agrochemistry. Accounting of the main eco-trophic groups of microorganisms was carried out by seeding various soil samples on agarized nutrient media. It was found that the amount of mineral and easily hydrolyzable nitrogen increased in the soil under the influence of ultraviolet radiation, indicating the photochemical destruction of humus and the formation of more mobile humic substances that are prone to leaching. A short-term decrease in the number of microflora participating in the mineralization of carbon- and nitrogen-containing organic matter was revealed under the influence of ultraviolet radiation. The susceptibility of microorganisms to the action of ultraviolet radiation was as follows: spore-forming bacteria < actinomycetes < nitrogen-fixing bacteria < oligotrophs < amylolytics < ammonifiers < micromycetes < nitrifiers. The change in the direction of organic matter transformation processes towards the activation of mineralization processes and the increase in the provision of microorganisms with easily accessible nutrients was demonstrated.