中文摘要：

以黑河中游7种典型土地利用方式（水田、旱地、中覆盖度草地、盐碱地、裸土地、戈壁和沙地）为对象，分析土壤有机碳含量及其组分的关系．结果表明：在0～100cm土壤中，随土层深度增加，土壤总有机碳（TOC）、活性有机碳（AOC）和非活性有机碳（NOC）含量逐渐降低．中覆盖度草地、盐碱地、裸土地、戈壁、沙地、水田和旱地中的TOC、AOC、NOC含量不同，土地利用方式的改变将引起土壤有机碳的增减，水田耕作是提高绿洲土壤有机碳的有效途径．当土地利用方式变化后，NOC对TOC含量的贡献大于AOC．同一种土地利用类型中，随TOC含量的增加，AOC、NOC含量也呈增加趋势，且NOC的增幅高于AOC．AOC、NOC变化趋势线的交叉点对应的TOC含量可作为土壤中TOC易积累或易损失的分界点，AOC、NOC的饱和容量可通过其变化趋势线来确定．

英文摘要：

Taking the seven typical land use types （paddy field, dry land, medium coverage grass- land, saline-alkali field, bare land, desert, and sandlot） in the middle reaches of Heihe River as test objects, this paper studied the relationships of soil organic carbon content with its components. In the 0-100 cm soil profile, the contents of soil total organic carbon （TOC） , active organic carbon （AOC）, and non-active organic carbon （NOC） decreased with increasing depth. The soil TOC, AOC, and NOC contents differed with land use type. Land use change induced the increase or decrease of soil organic carbon content. The tillage in paddy field was an available way to increase the contents of soil TOC, AOC, and NOC. After land use change, soil NOC rather than AOC contributed more to soil TOC content. For the same land use types, soil AOC and NOC contents increased together with＇ increasing soil TOC content, and the NOC content increased faster than the AOC content. The soil TOC content corresponding to the crossing point of the variation trend lines of soil AOC and NOC contents could be considered as the boundary point of TOC accumulation or loss, and the saturation capacities of soil AOC and NOC could be obtained by the variation trend lines of the AOC and NOC.