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基于野外采样和实验室分析,研究了民勤绿洲土壤的可溶盐特征。结果表明,表层土壤中阴离子以氯离子和硫酸根离子为主,阳离子以钙离子和镁离子比重较大;民勤表层土壤中硫酸盐矿物居多,硫酸根离子易与阳离子结合形成硫酸盐化合物,而且硫酸根离子与钙、镁离子的相关系数达0.918、0.933,说明土壤中硫酸根离子与钙离子、镁离子是主要的结合方式。采用线性方程拟合土壤浸提液电导率和土壤全盐量的关系,精度较高。通过表层土壤的光谱测量和光谱特征分析,发现反射率一阶微分和反射率对数一阶微分两种变换形式与土壤全盐量的相关性最强。利用多元逐步线性回归方法,以反射率对数一阶微分为自变量的回归方程效果最佳,预测方程的决定系数达到0.789。
Based on field sampling and laboratory analysis, the characteristics of soluble salt in Minqin oasis soils were studied. The results showed that the anions in the topsoil were mainly chloride and sulfate, while the cations had larger specific gravity of calcium and magnesium ions. The sulfate minerals in the surface soil of Minqin were mostly, the sulfate ions could easily combine with the cations to form sulfate compounds, Moreover, the correlation coefficient of sulfate ion with calcium and magnesium ions reached 0.918,0.933, indicating that the sulfate ion in soil is mainly combined with calcium ion and magnesium ion. The linear equation is used to fit the relationship between the conductivity of soil extract and the total salt content of soil, with higher accuracy. Through the spectral measurement and spectral analysis of surface soils, it was found that the correlation between the first derivative of reflectivity and the first derivative of logarithm of first order of reflectivity and soil total salinity was the strongest. Using multivariate stepwise linear regression, the regression equation with first-order logarithm of logarithm of reflectivity as independent variable had the best effect, and the coefficient of determination of the prediction equation reached 0.789.