Assessment of Organic Carbon Stocks in Arid Degraded Soils of Southern Russia

Arid regions have received little attention in carbon management studies so far. The results of assessment and comparison of organic carbon stocks in arid soils with different degrees of degradation in the arid zone of southern Russia (Astrakhan oblast) are provided. Based on the analysis of data characterizing 263 soil profiles, it was found that carbon stocks decrease with an increase in the degree of degradation. Significant spatial variability is observed both between and within biogeocenoses. The results showed that automorphic soils have a lower capacity for organic carbon deposition compared to hydromorphic soils. In automorphic soils, carbon stocks are 9.37 ± 1.02 t ha^–1, which is four times lower than in hydromorphic soils at 37.01 ± 2.34 t ha^–1. It was found that hydromorphic solonchaks in the coastal areas of crustal solonchaks of a very strong degree of degradation in the complete absence of vegetation have organic carbon stocks at the level of automorphic zonal soils.