The researchers studied the organic carbon in soil layers of Xia Laxiu region in Qinghai-Tibet plateau. They found that different layers had varying amounts of organic carbon, with the grass-growing layer having the highest levels. Labile organic carbon and water-soluble substances were present in all layers, increasing in deeper layers. Fulvic acid and humin content differed between layers, while humic acid content did not. The humification degree of organic substances in the profile varied, with the grass-growing layer not representing the highest or lowest degree.