Assessment of Carbon Reserves in Grey Forest Soils Under Different Types of Land Use

The research was conducted to study carbon reserves in soil layers under different types of land use. The object of the study was the gray residual carbonate forest soils of the Republic of Tatarstan. The work was carried out on sites with different types of land use: arable land (PL), land with the removal of phytomass (U), land without the removal of phytomass (UV) and fallow lands (W). The analysis was performed using the methods of spectrophotometry, real-time polymerase chain reaction (PCR-RV) and gas chromatography, which made it possible to determine the content of total organic carbon (TOC), soluble organic carbon (ROC), microbial biomass carbon (Smic) and the number of bacteria in soil horizons. Arable lands were characterized by experimentally minimal reserves of Sorghum in the meter layer – 189.67±10.44 t/ha, due to intensive tillage and mineralization of organic matter. Minor differences were noted in fallow lands and a sloping area with the removal of phytomass, where its reserves amounted to 255.03±21.35 and 287.14±28.01 t/ha, respectively. The maximum reserves were recorded at the site with mowing without removing phytomass – 322.49±19.4 t/ha, which indicates the high role of plant residues in the accumulation of organic compounds. Most of the carbon reserves are concentrated in the upper half of the meter: 52…78 % for Sorg, 40…59 % for ROE and 47…63 % for Smic. The content of ROE and Smic changes faster under the influence of external factors, in contrast to the more stable soil organic matter. According to their stocks, the studied samples were arranged in the following order: for RAW materials P UV, for Smik – UV P W U. The main part of the Smic is concentrated in the upper horizons, where the processes of decomposition of organic matter are active. Regular mowing with the remaining phytomass on the soil surface provides the greatest potential for accumulation of both total and soluble organic carbon.