西北地区种植甘草对土壤次生盐渍化的影响

目的]研究西北地区植被特征指标与土壤表层盐含量、碱性间的相互关系,为该区土壤次生盐渍化防治工作提供科学依据。方法]以甘草(Glycyrrhiza uralensis)植被和其下部土壤为研究对象,通过测定甘草植被的盖度、高度、地上生物量和其下部土壤表层(0—5cm)的含水率、pH值、电导率、盐含量等指标,并利用SPSS统计软件进行分析。结果]甘草植被的盖度、高度、地上生物量和其下部土壤的含水率均随甘草生长年限的增加呈显著升高的趋势(p0.05),而土壤的pH值、电导率、盐含量正好相反,均表现出显著降低的趋势(p0.05);相关分析结果显示,耕地表层土壤的pH值、盐含量与甘草植被特征指标间呈显著的负相关关系,相关系数的大小顺序均为:植被盖度植株高度地上生物量;回归分析显示,土壤pH值和盐含量与甘草植被的这3个性状指标间均表现为负线性函数关系,甘草植被的盖度、高度、地上生物量每提高1个单位,可使土壤表层的pH值分别下降0.012,0.011和0.002,盐含量分别降低0.108,0.107,0.015g/kg。结论]西北干旱地区耕地中种植甘草对其下部土壤表层的盐含量和碱性(pH值)影响显著,其中植被的盖度对表层土壤的盐碱影响最大;从耕地表层抑盐角度考虑,应优先选择种植枝叶稠密、植株高大的作物。

Effects of Glycyrrhiza Uralensis Plantation on Soil Secondary Salinification in Northwest China

Objective] The relationship between salinification and alkaline of topsoil and vegetation cover was analyzed to provide scientific basis for the prevention and control of soil secondary salinization in this area.Methods] Plant height, aboveground biomass of glycyrrhiza community and soil moisture, pH value, salt content in soil surface(0-5 cm) were measured. The relationships between indexes of vegetation characteristics and physical and chemical indexes of topsoil through measuring vegetation coverage were analyzed.Results] With the extension of growing years, the vegetation coverage, plant height and aboveground biomass of Glycyrrhiza uralensis appeared an increasing trend. On the contrary, salt content and pH value of topsoil indicated a decreasing trend. Correlation analysis displayed, there was a negative relation between soil salt content and pH value of topsoil and all indexes of vegetation characteristics. Correlation coefficients ranked as vegetation coverage > plant height > aboveground biomass. Regression analysis indicated, salt content and pH value of topsoil and indexes of vegetation characteristics all showed a negative linear relation. When coverage, height and aboveground biomass of Glycyrrhiza uralensis vegetation each increased one unit, pH values of topsoil decreased 0.012, 0.011 and 0.002, salt content of topsoil decreased 0.108, 0.107 and 0.015 g/kg.Conclusion] Vegetation significantly influenced salt content and pH value of topsoil. The most influence index is vegetation. When only considering the restraining of soil salt, those crops with more branches and leaves, and with high stalks should be selected.