The study looked at how soil organic carbon (SOC) is distributed in the Loess Plateau in China. They collected soil samples from different depths and found that SOC decreases with depth. Forestland had the highest SOC, followed by cropland and grassland. Land use mainly affects SOC in shallow soil layers, while soil factors like clay content and water content are more important in deeper layers. The study showed that a significant amount of organic carbon is stored in deep soil layers, highlighting the importance of understanding and managing carbon in these areas for ecosystem health.