拉萨河下游湿地土壤养分特征与肥力评价

Soil Nutrient Characteristics and Fertility Evaluation of Wetland in the Lower Reaches of the Lhasa River

[目的]为探索拉萨河下游湿地土壤的养分特征和肥力状况。[方法]选取甘曲湿地、巴嘎雪湿地、拉鲁湿地和茶巴朗湿地4个代表性区域的土壤为研究对象,共采集69份土壤样本,测定样品的pH、总氮(TN)、总磷(TP)、总钾(TK)、全盐、电导率、氧化还原电位(redox potential)、阳离子交换量(CEC)和有机质(OM)值,并利用改进内梅罗综合指数法对湿地土壤肥力进行全面的评价。[结果](1)研究区土壤的pH范围为5.77~7.78,均值为6.62,呈中性;有机质和总氮的相关性强,分布特征相似,含量分别为61.82,3.13 g/kg,均为很丰富的状态,属于一级水平;总磷和总钾含量分别为0.75,18.05 g/kg,为适中的状态,属于三级水平;全盐含量为0.92 g/kg,电导率为2.97 mS/m,整体来看,研究区土壤具有较强的保肥能力。(2)湿地土壤综合肥力系数(P)顺序为茶巴朗湿地(2.01)>巴嘎雪湿地(1.95)>拉鲁湿地(1.93)>甘曲湿地(1.86),均属于肥沃等级,影响湿地土壤综合肥力的指标是总钾,因各自然湿地形成条件相似,土壤综合肥力系数无显著差异。[结论]研究结果明晰了拉萨河下游湿地土壤养分现状,为实现研究区湿地资源的可持续利用提供科学依据。

[Objective]To explore the nutrient characteristics and fertility status of wetland soil in the lower reaches of Lhasa River.[Methods]A total of 69 soil samples were collected from the four representative regions of Ganqu Wetland,Baga Snow Wetland,Lalu Wetland and Chabalang wetland.The values of pH,total nitrogen,total phosphorus,total potassium,total salt,electrical conductivity,redox potential,cation exchange capacity and organic matter of the samples were determined.The improved Nemerow composite index method was used to evaluate the wetland soil fertility comprehensively.[Results](1)The pH range of the soil in the study area was 5.77~7.78,with an average value of 6.62,which was neutral.The correlation between organic matter and total nitrogen was strong,and the distribution characteristics were similar.The contents of organic matter and total nitrogen were 61.82 and 3.13 g/kg,respectively,and both were very abundant,belonging to the first level.The contents of total phosphorus and total potassium were 0.75 g/kg and 18.05 g/kg,respectively,which were moderate and belonged to the tertiary level.The total salt content is 0.92 g/kg,and the electrical conductivity is 2.97 mS/m.On the whole,the soil in the study area had strong fertilizer retention ability.(2)The soil comprehensive fertility coefficient(P)of wetland was in the order of Chabalang Wetland(2.01)>Bagaoxue Wetland(1.95)>Lalu Wetland(1.93)>Ganqu Wetland(1.86),all belonging to the fertility level.The index affecting the soil comprehensive fertility of wetland was TP,because the formation conditions of natural wetlands were similar.There was no significant difference in soil comprehensive fertility coefficient.[Conclusion]The present situation of wetland soil nutrients in the lower Lhasa River was clarified,which provides scientific basis for realizing the sustainable utilization of wetland resources in the the study area.