Post-Pasture Restoration of Biological Activity of Soils in the Dry-Steppe Zone

Abstract

The biological activity of soils of solonetz associations in the dry steppe zone of the western part of the Yergeni Upland has been studied. The biomass, trophic structure, and metabolic profiles of microbial communities, as well as the enzymatic activity of soils, have been studied in areas with intensive grazing and in areas, where species not consumed by livestock became dominant and grazing is now absent as a result of plant community succession under overgrazing. It is found that the content of microbial biomass in the upper layers of chestnut soil and solonetz in the area without grazing is practically the same. The microbial biomass under grazing is maximal in the solonetz and exceeds the values in other soils by 40–63%. The total enzymatic activity, in particular the activity of carbon cycle enzymes, positively and significantly correlates with microbial biomass. The activity of leucine aminopeptidase and arylsulfatase correlates with the content of exchangeable Na⁺, which indicates a relationship with the solonetz process. The metabolic diversity of microbial communities is the highest in chestnut soil of an ungrazed plot 200 m from the farm. Microorganisms in the upper layer of this soil are characterized by high-amplitude respiration respond to almost all proposed inducers of the groups of amino acids, salts of carboxylic acids, carbohydrates, and alcohols/ethers. The metabolic diversity is significantly lower at a distance of 800 m from the farm, in the intensively grazed zone.