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研究土壤C∶N的变化有助于深入理解土壤有机碳氮的积累过程及其土壤质量的变化趋势。以黄土高原丘陵沟壑区砖窑沟小流域为单元,基于地貌类型和土地利用方式两大因素,采集737个土壤样品,研究流域内土壤C∶N的变化差异及其影响因素。梁峁坡上,林地和草地0～20 cm土层的土壤C∶N分别是农田土壤C∶N的1.13和1.03倍;沟坡上,林地、草地和农田土壤的C∶N分别为13.88、12.58、9.02。农田条件下,梁峁坡、沟坡和沟谷的土壤C∶N分别为10.34、9.02和10.77;林地条件下,沟坡和梁峁坡的土壤C∶N分别为13.88、11.67;草地条件下,沟坡土壤C∶N是梁峁坡土壤C∶N的1.19倍。同一地貌类型或土地利用方式条件下,土壤C∶N均呈现表层大于深层的趋势,0～20 cm和20～40 cm土层的土壤C∶N分别是40～100 cm土层土壤C∶N的1.05～1.17和1.16～1.42倍。
Studying the change of soil C: N will help us to understand deeply the process of soil organic carbon and nitrogen accumulation and the change trend of soil quality. Based on the two major factors of the landform and the pattern of land use, a total of 737 soil samples were collected to study the variation of soil C: N and its influencing factors in the watershed. Soil C: N in 0 ~ 20 cm soil layer on slope, slope and grassland of Lianggao was 1.13 and 1.03 times of C: N in soil of farmland respectively. The C: N of soil on slope, forest land, grassland and farmland was 13.88, 12.58,9.02. Under farmland conditions, the soil C: N ratios were 10.34, 9.02 and 10.77 in Liangcao, Gou and Gully valleys, respectively. Under the conditions of forestland, the soil C: N of the slope and Liangpo slope were 13.88 and 11.67, C: N of the slope soil is 1.19 times of C: N of the slope of the slope. Under the same landform types or land use types, soil C: N showed a trend of surface layer larger than deep layer. Soil C: N in 0-20 cm and 20-40 cm soil layers were C: N Of 1.05 ~ 1.17 and 1.16 ~ 1.42 times.