宁夏荒漠草原不同土地利用方式对土壤活性有机碳的影响

以宁夏荒漠草原不同土地利用方式(耕地、弃耕地、草地和柠条地)的土壤为研究对象,测定了不同土层土壤有机碳和活性有机碳含量,分析了土壤活性有机碳占有机碳的比例,以期探寻不同土地利用方式对土壤活性有机碳的影响。结果表明:不同土地利用方式土壤总有机碳含量范围在1.78~6.17 g·kg^-1,具体表现为弃耕地>柠条地>草地>耕地。表层(0~5 cm)土壤有机碳含量显著高于深层(10~60 cm),说明荒漠草原土壤有机碳主要富集在表层;4种土地利用方式土壤易氧化有机碳含量为0.57~1.38 mg·g^-1,变化趋势具体表现为柠条地>草地>耕地>弃耕地,且柠条地在每个土层都高于其它3种土地利用方式;土壤可溶性有机碳含量范围为6.8~11.1 mg·kg^-1,变化趋势表现为草地>耕地>柠条地>弃耕地。土壤易氧化有机碳含量占有机碳的比例范围为13.7%~43.1%,大小排序为柠条地>耕地>草地>弃耕地;土壤可溶性有机碳含量占有机碳的比例范围为0.11%~0.48%,比例大小为耕地>草地>柠条地>弃耕地,耕地和草地中土壤可溶性有机碳含量占有机碳比例随着土壤深度的增加而减小,这与有机碳在耕地和草地中变化趋势一致。土地利用变化可以显著影响土壤活性有机碳的含量与分布,能够敏感的反映土壤碳库的变化,可以作为评价宁夏荒漠草原土壤质量和肥力的指标之一。

Effects of Different Land Use Types on Soil Active Organic Carbon in Desert Steppe of Ningxia

The content of soil organic carbon and active organic carbon under different land use patterns(arable land,derelict land,grassland and woodland) in Ningxia desert steppe was determined,and the proportion of soil active organic carbon to organic carbon was analyzed in order to explore the influence of different land use patterns on soil active organic carbon.The proportion of soil active organic carbon in organic carbon and the soil driving factors that affect the soil active organic carbon had been analyzed.The results showed that the total content of soil organic carbon in the four land use types ranges from 1.78 g·kg^-1 to 6.17 g·kg^-1,which was obviously showed by the trend of derelict land>horqin peashrub land>grassland>arable land.And the content of organic carbon in the surface layer(0-5 cm) was significantly higher than that of the deep soil layer(10-60 cm),which indicated that soil organic carbon was mainly enriched in the surface layer.The content of easily oxidizing organic carbon in the four land use types ways ranges from 0.57 mg·g^-1 to 1.38 mg·g^-1,and the changing trend was specifically showed by horqin peashrub land>grassland>arable land>derelict land.Besides,content of the horqin peashrub land was higher than the other three types of land in each soil layer.The soil water soluble organic carbon content of these four lands was from 6.8 mg·kg^-1 to 11.1 mg·kg^-1,which was showed by grassland>arable land>forestland>derelict land.The proportion of easily oxidizing organic carbon in these four lands was from 13.7% to 43.1%,which was showed by horqin peashrub land>arable land>grassland>derelict land.And the proportion of water soluble organic carbon in these four lands was from 0.11% to 0.48%,which was showed by arable land>grassland>horqin peashrub land>derelict land.The proportion of water soluble organic carbon in arable land and grassland declines with the rises of soil depth,which was consistent with the trend of organic carbon in arable land and grassland.Land use change could significantly affect the content and distribution of soil active organic carbon,and could sensitively reflect the change of soil carbon pool.It could be used as one of the indicators to evaluate soil quality and fertility in Ningxia desert steppe.