Climate and land use as key factors of the stability of organic matter in soils

Stocks of organic carbon in the soils and its resistance to biodegradation depend on a combination of external and internal determinants which control not only the decomposition, but also the stabilization of organic matter (OM). Soil OM stability was evaluated: 1) by specific mineralization rate (SpMinR) for the forest ecosystems located in various climatic zones of Eurasia (temperate, Mediterranean, and tropical) and 2) by the biological stability index (IBS), determined for the main soil types of the European part of Russia under natural vegetation and agricultural crops. It is shown that the key factors determining the stability of OM of substances in soils are the climate and type of vegetation (land use). Thus, a close negative correlations between the SpMinR values and the annual precipitation and the average annual air temperature were found in the soils of the Eurasian transect. It was revealed that the share of stable and biologically conservative OM and IBS values in the soils under agricultural crops were significantly higher than in the soils of natural cenoses.