[Profile Distribution of Soil Organic and Inorganic Carbon Under Different Land Use Types in the Loess Plateau of Northern Shaanxi].

Carbon storage in the Loess Plateau is affected by land use. In order to assess the differences in soil organic carbon (SOC) and soil inorganic carbon (SIC) under different land use patterns in deep soil profiles, we investigated the distribution characteristics of SOC and SIC at 0-20.0 m soil depth at three locations in the northern Shaanxi province (i.e., an economical plantation in Mizhi, a reforestation area in Shenmu, and a wind break and sand fixation forest district in Yuyang). The results showed that the order for SOC content was:pruning jujube tree (2.00 g·kg-1) > jujube tree (1.54 g·kg-1) > Caragana (0.97 g·kg-1) > degraded artificial grassland (0.81 g·kg-1) > pine forests (0.70 g·kg-1) > natural grass field (0.45 g·kg-1), which indicated significant differences between SOC content and land use types (P<0.05). Similarly, the order of SIC content was:pruning jujube tree (11.66 g·kg-1) > jujube tree (11.59 g·kg-1) > Caragana (9.62 g·kg-1) > degraded artificial grassland (8.07 g·kg-1) > pine forests (4.32 g·kg-1) > natural grass field (0.47 g·kg-1). There were no significant differences between SIC content and soil profiles under the economical plantation of Mizhi and the reforestation area of Shenmu. There were significant differences for SIC content between an artificial economic forest, an area returning farmland to a forest (grass) profile, and a windbreak and sand fixation forest (P<0.05). The SIC densities for pruning jujube tree, jujube tree, Caragana, degraded artificial grassland, pine forest, and natural grass field were 6.19, 7.71, 10.70, 10.78, 5.91, and 1.03 times that of its corresponding SOC density, respectively. It has been concluded that the soil carbon storage was significantly different for different land use patterns, and the SIC content was much higher than the SOC content in the soil profile.