宁夏地区不同土地利用类型的土壤有机碳特征及其影响因素

Characteristics and influencing factors of soil organic carbon in different land use types in Ningxia

以宁夏全区为研究对象,在不同土地利用类型(林地、耕地、草地、荒草地)布设121个土壤剖面,采集测定0~120 cm土层样品,研究宁夏不同土地利用类型下土壤有机碳(SOC)特征及其影响因素.结果表明,在0~120 cm剖面上,w(SOC)均值为5.49×10-3,变异系数达90.71%.林地w(SOC)均值为1.59×10-2,是耕地的2.81倍,草地的3.22倍,荒草地的4.79倍;不同土地利用类型的w(SOC)在0~30、 30~80、 80~120cm土层和0~120 cm剖面中均表现为林地>耕地>草地>荒草地,差异显著.林地SOC与全氮、全磷和阳离子交换量呈极显著性正相关,与pH呈极显著性负相关,耕地SOC与全氮、全磷、阳离子交换量和黏粒呈极显著性正相关,草地SOC与全氮、全磷和阳离子交换量呈极显著性正相关,与pH呈极显著性负相关,荒草地SOC与全氮呈极显著性正相关.不同土地利用类型w(SOC)的影响因素存在差异,全氮、全磷和阳离子交换量是影响宁夏SOC的关键土壤理化因子.宁夏不同土地利用类型的w(SOC)差异显著,且全氮、阳离子交换量和全磷对其影响贡献度较大.

With Ningxia as the research object,121 soil profiles were set up in different land use types(forest land,cropland,grassland and barren-grassland),and 0-120 cm soil samples collected and measured to study the characteristics and influencing factors of soil organic carbon(SOC).The results showed that,in the 0-120 cm profile,the mean of w(SOC) was 5.49×10-3 and the coefficient of variation 90.71% in Ningxia,indicating a strong spatial heterogeneity.The mean of w(SOC) in forestland was 1.59×10-2,which was 2.81 times of cropland,3.22 times of grassland and 4.79 times of barren-grassland;w(SOC) of different land use types in 0-30,30-80,80-120 cm soil layer and 0-120 cm profile showed an order of forestland>cropland>grassland>barren-grassland,with were significant differences between them.w(SOC) in forestland was significantly positively correlated with total nitrogen,total phosphorus and cation exchange capacity,and negatively correlated with pH;in cropland significantly positively correlated with total nitrogen,total phosphorus and cation exchange capacity,and clay;in grassland significantly positively correlated with total nitrogen,total phosphorus and cation exchange capacity,and negatively correlated with pH.There was a significant positive correlation between w(SOC) and total nitrogen in barren-grassland.The influencing factors of w(SOC) of different land use types were different;total nitrogen,total phosphorus and cation exchange capacity were the key soil factors affecting w(SOC) in Ningxia.There were significant differences in w(SOC) among different land use types,and total nitrogen,cation exchange capacity and total phosphorus contributed significantly to SOC.