Soil carbon distribution characteristics and influencing factors in typical desert areas of Urad Rear Banner

To improve our understanding of the distribution characteristics of soil carbon in the arid desert areas of Northwest China, the typical desert area in the western part of Urad Rear Banner was chosen as the research object. Through a combination of profile investigation, sample collection, and laboratory analysis, the distribution characteristics of soil organic carbon and inorganic carbon content in the region and influencing factors were explored. The overall soil organic carbon content in the region decreased with increasing soil depth, falling from 1.92 g·kg−1 in the 0-20 cm layer to 0.57 g·kg−1 at depths exceeding 1 m, whereas the overall soil inorganic carbon content increased with increasing soil depth, rising from 5.13 g·kg−1 in the 0-20 cm layer to 8.71 g·kg−1 at depths exceeding 1 m. The average inorganic carbon content in each soil layer was several fold greater than the organic carbon content, and the soil inorganic carbon content was 4.31-fold greater than the organic carbon content in the 0-120 cm layer. Soil organic carbon and inorganic carbon content exhibited high variability. Among soil physical and chemical factors, factors excluding available phosphorus and available Kalium exhibited significant or highly significant linear correlations with soil organic and inorganic carbon content. The random forest regression model could explain 25% of the variation in soil organic carbon content and 70% of that in inorganic carbon content. Cation exchange capacity, ammonium nitrogen, silica, silt content, iron oxides, and sand content were identified as significant influencing factors for organic carbon content (all PP<0.01). This study provides basic data support for research on carbon cycling processes and the evaluation of carbon sink capacity in desert ecosystems.