Soil Properties Sensitivity to Land-Use Change from Cropland to Abandoned Land

The conversion of land use is a crucial factor in the dynamics of soil carbon stocks. The widespread abandonment of cropland that began in Russia during the 1990s resulted in vegetation and soil restoration. This led to changes in soil properties and carbon fluxes within the plant-soil-atmosphere system. The aim of the study was to investigate the effects of post-agricultural soil restoration on the rate of changes in soil properties, specifically organic carbon (C_org) and total nitrogen (N_total) contents, microbial respiration rate, and activity of hydrolytic enzymes. A post-agricultural chronosequence formed on Haplic Luvisols, including current cropland, 7- and 25-year-old postagrogenic abandoned land, and mesophytic grassland, was studied. The rate of changes in soil properties during post-agricultural restoration was evaluated based on their sensitivity to land use changes, with a comparison of changes in soil organic carbon content. The least sensitive properties to land use change were found to be C_org and N_total in the mineral-associated organic matter fraction, and pH values. The content of water-soluble nitrogen, C_org and N_total in the free and occluded organic matter fractions, as well as β-glucosidase and chitinase activity, were the most sensitive to land use changes. Consequently, the recovery of sensitive soil properties in the upper 10 cm is complete within the first decade after tillage is stopped. In contrast, the restoration of less sensitive properties requires more than 20 years.