Abstract:

  The study area is located in the Yaoba oasis irrigated area in the Alxa League of Inner Mongolia. Based on the field investigation, soil samples collection and indoor experiment analysis, using descriptive statistical method, correlation analysis method, principal component analysis (PCA) method, this article analyzed the distribution characteristics of surface soil total salt and salt ions in Yaoba oasis. According to descriptive statistical analysis, the results showed that surface soil of Yaoba oasis was alkaline chlorine-sulfate soil salinization. The cations accumulation of surface soil were dominated by salt ions of Ca²⁺,K⁺+Na⁺ and the anion accumulation of surface soil was dominated by salt ion of HCO₃^-.The distribution characteristics of soil total salt presented high values in the southwest and low values in the northeast. Soil total salt varied largely from east to west and varied small from south to north. In surface soil, the salt ions of HCO₃^-, K⁺+ Na ⁺, SO₄^2- and Cl^- presented strong variability; soil total salt, salt ions of Ca²⁺, Mg²⁺ and HCO₃^- presented moderate variability; pH presented weak variability. Through correlation analysis, it showed that soil total salt had the significant positive correlation with soil salt ions of SO₄^2-,Ca²⁺,K⁺+Na⁺,Cl^-,Mg²⁺andthe highest correlation coefficient was 0.958 with ion of SO₄^2-; but pH had the significant negative correlation with soil salt ions of Mg²⁺,Ca²⁺,Cl^-,SO₄^2- and all correlation coefficients were less than 0.6. According to principal component analysis(PCA) , it showed that there were two principal component factors which could present the characteristics of surface soil salt in study area. One principal component factor presented soil salt component and another principal component factor presented alkalinity, so it concluded that salt ions of SO₄^2-, K⁺+Na⁺, Ca²⁺,Cl^- were the key characteristics factors of soil salinization. At the end, this study established the equations of principal component comprehensive score. According to comprehensive score calculation of 42 soil samples, the value range was 3.6~10.7, the average value was 5, the standard deviation was 1.5, so the comprehensive score presented moderate variability. The study results will provide theory and practical basis for prevention and control soil salinization and can make sure security development of agriculture and animal husbandry in study area.

Key words: surface soil, soil salt, principal component analysis, Yaoba oasis, Inner Mongolia