西藏“一江两河流域”草地土壤养分含量及化学计量特征研究

A Study of Soil Nutrient Content and Chemometrics of Grassland in the"One River and Two Rivers Basin"of Xizang

土壤有机碳、氮、磷、钾等化学成分在土壤物质循环及生物过程中扮演着重要角色,明确土壤有机碳、氮、磷、钾含量及空间分布对土壤资源管理和可持续开发利用具有重要意义。本研究对西藏“一江两河流域”草地土壤有机碳、全氮、全磷和全钾含量空间分布特征进行研究。结果表明:(1)土壤有机碳、全氮、全磷和全钾含量均随土壤深度增加呈降低的趋势。在0~60 cm土壤深度,有机碳、全氮、全磷和全钾含量分别介于12.62~46.72、0.91~2.05、0.24~0.62、4.96~9.10 g·kg^(-1),其均值分别为30.66、1.49、0.42、6.98 g·kg^(-1),可见“一江两河流域”草地土壤肥力水平较低,均属于矿质土壤。(2)不同县域间草地土壤有机碳、全氮、全磷和全钾含量存在不同程度的差异,且异质性较大。(3)草地土壤C/N、C/P、C/K和N/P分别介于10.97~29.96、33.79~100.15、1.67~6.96和2.86~5.68,其均值分别为20.17、71.08、4.39和3.57。N/P显著低于全球平均水平(14.00),说明本研究区域为明显的N元素限制类型。(4)土壤C/N与C/P和C/K化学计量比之间具有极显著(P<0.01)正相关关系,即土壤N、P、K含量均随有机碳含量的增加而增加。

Soil organic carbon,nitrogen,phosphorus,potassium and other chemical components play an important role in the soil material circulation and biological processes.It is of great significance to clarify the content and spatial distribution of soil organic carbon,nitrogen,phosphorus and potassium for the management of soil resources and sustainable development and utilization.This sresearch studied the spatial distribution characteristics and influencing factors of organic carbon,total nitrogen,total phosphorus and total potassium content in the grassland soil of"One River and two River basins"in Xizang.The results showed that:(1)The content of organic carbon,whole nitrogen,whole phosphorus and whole potassium in the soil tended to decrease with the increase of soil depth.At a soil depth of 0~60 cm,the contents of organic carbon,whole nitrogen,whole phosphorus and whole potassium ranged from 12.62~46.72,0.91~2.05,0.24~0.62,4.96~9.10 g·kg^(-1),respectively,and their values were 30.66,1.49,0.42 and 6.98 g·kg^(-1),respectively.It can be seen that the grassland soil fertility level of"one river and two river basins"is low,all of which belong to mineral soil.(2)There were different degrees of differences in the content of organic carbon,whole nitrogen,total phosphorus and total potassium in grassland soils between different counties,and the heterogeneity was large.(3)Grassland soil C/N,C/P,C/K and N/P were between 10.97~29.96,33.79~100.15,1.67~6.96 and 2.86~5.68 respectively,with average values of 20.17,71.08,4.39 and 3.57 respectively.N/P was significantly lower than the global average(14.00),indicating that this study area is an obvious type of N element restriction.(4)There was a very significant(P<0.01)positive correlation between soil C/N and C/P and C/K chemometric ratios,that is,soil N,P and K content increased with the increase of organic carbon content.