Particulate Organic Matter in Noncultivated and Arable Soils

Abstract

Data on the contents of particulate organic matter (POM) in the humus horizons of different soil types were obtained. The influence of the land use system and fertilizers on the carbon of particulate organic matter (C_POM) in gray forest soil and typical chernozem was shown. The mineralization rate of POM under constant conditions of temperature and moisture was estimated, and the ratios between the pools of POM and biologically active organic matter in the soils were calculated. In the soils of natural cenoses, the percentage of POM together with the sand particle-size fraction varied within 12–36% of the soil mass, and the C_POM content varied from 1.66 to 8.03% of the fraction mass. The portion of C_POM in the total C_org ranged from 20 to 48%. Cultivated gray forest soil and typical chernozem were depleted of C_POM by 3.0–3.2 and 2.0–2.8 times, respectively, in comparison with the samples of noncultivated soils. The mineralization rate of POM in the gray forest soil and typical chernozem was about the same (7.9–12.1 and 7.2–8.2% of C_POM, respectively), which was about 1.2–2.4 times higher than the mineralization rate of the total soil organic matter. It was noted that POM could be a sensitive indicator of the C_org dynamics in the soil, a good predictor of changes in the content and quality of soil organic matter, and a significant source of potentially mineralizable organic matter in the soil.