Influence of sideral crops on the enzymatic soil activity

Soil enzymes play a key role in the transformation of organic matter. Indicators of soil enzymatic activity are used as the most operational indicators of anthropogenic impact on the soil. The purpose of the research is to study the effect of green manure crops on the enzymatic activity of the soil in the crops of subsequent crops of the crop rotation link. The enzymatic activity of soils was determined three times during the growing season of crop rotation in air-dry samples by the Galstyan method. In the studies, the activity of some enzymes belonging to the class of oxidoreductases was determined: catalase (AA), peroxidase (PO) and polyphenol oxidases (PFO). The territory of the experimental site is included in the foothill continental zone of a moderately warm climate with moderate humidification of the Kabardino-Balkarian Republic. The peroxidase activity of the soil in the first year was higher in the control variant, where winter wheat was cultivated according to the predecessor wheat and in the variant of sideration with white mustard. The lowest polyphenol oxidase activity of the soil under winter wheat was observed after sideration with spring vetch, the level of enzyme activity decreased by 13% relative to the control variant. The intensity of the process of humus accumulation under winter wheat was higher in the pea green manure fallow and in the variant of green manure with Sudan grass compared to the control variant by 26.6 and 15.5%, respectively. On the second crop of the crop rotation (corn for grain), the soil in the mustard green manure fallow (14.5 mg/1 g w.s. of soil) and in the control variant (14.9 mg/1 g w.s. of soil) was characterized by high catalase activity. The activity of polyphenol oxidase involved in the synthesis of humus in pea green manure fallow was maximum in the experiment (6.8 mg/1 g of w.m. of soil). In the second year of aftereffect, the humus accumulation coefficient in the control was the smallest one (73.0). The processes of humus accumulation were more intense during sideration with peas and spring vetch, as evidenced by the increase in the coefficient of humus accumulation relative to the control by 17.1 and 15.8, respectively. Differences in the direct action and aftereffect of the studied green manure fallows on the enzymatic activity of the soil were associated with the unequal amount of the biological mass of green manure crops entering the soil and their different chemical composition. The use of green manure increases the activity of polyphenol oxidase involved in the synthesis of humus.