Key Laboratory of Continental Dynamics and Mineralization Prediction of Central Asian Orogenic Belt, Xinjiang University, Urumqi, 830017, China.
Environ Geochem Health. 2024 Sep 24;46(11):442. doi: 10.1007/s10653-024-02223-9.
Soil salinization poses a significant ecological challenge, emerging as a critical constraint to agricultural development in the arid and semi-arid regions of China, especially in southern Xinjiang. In particular, Yuepuhu County, situated in Kashgar, faces a distinctive issue. Impermeable thin clay layers within the vadose zone impede year-round leaching of salts, significantly impacting the growth of cotton. Through a combination of indoor testing, experiments, and statistical analyses, this study elucidated the varying permeability of soil layers at different depths and explored the forms and accumulation characteristics of soil salts in Yuepuhu County. It unveiled patterns of water and salt movement in soils with variable permeability layers, identifying key influencing factors. The research also proposed an irrigation regime suitable for cultivating vadose zone soils in the local context. The findings revealed a progression of increasing soil complexity and decreasing burial depth of clay layers from northwest to southeast, aligned with the direction of groundwater flow. With increasing depth, a noticeable reduction in soil saturated hydraulic conductivity was observed, indicating significant variability in permeability. Predominantly chloride-sulfate type saline soils in Yuepuhu County contained potassium (K) and sodium (Na) as the main cations in surface soils. Salinity strongly correlated with calcium (Ca) and magnesium (Mg). Chloride (Cl), sulfate (SO), K, Na, and bicarbonate (HCO) reflected the degree of soil salinization in Yuepuhu County. The clay interlayers in variable permeability zones significantly impeded water and salt movement in the vadose zone. Moving from west to east, thicker and shallower clay interlayers hindered downward water movement, increasing the difficulty of salt leaching. Additionally, the irrigation regime influenced water and salt movement in the vadose zone. Under the same soil structure, flood irrigation with a higher water flux resulted in more significant salt leaching, and lower total dissolved solids (TDS) in irrigation water were more favorable for effective salt leaching. Collectively, our findings provided a theoretical foundation for improving and managing local saline soils, as well as guiding the implementation of rational agricultural irrigation practices.
土壤盐渍化是一个严重的生态挑战，尤其是在中国干旱和半干旱地区，如新疆南部的农业发展受到严重制约。特别是在喀什的岳普湖县，存在一个独特的问题。包气带中不透水的薄粘土层阻碍了全年盐分的淋洗，这对棉花的生长有很大的影响。通过室内测试、实验和统计分析相结合，本研究阐明了不同深度土壤层的变化渗透性，探讨了岳普湖县土壤盐分的形态和积累特征。揭示了具有不同渗透性土层土壤中水分和盐分运动的模式，确定了关键影响因素。研究还提出了一种适合当地条件的灌溉制度，以种植包气带土壤。研究结果表明，土壤复杂性从西北向东南逐渐增加，粘土层的埋藏深度逐渐减小，与地下水的流向一致。随着深度的增加，土壤饱和导水率显著降低，表明渗透性有很大的变化。岳普湖县主要为氯-硫酸盐型盐渍土，表层土壤中钾（K）和钠（Na）为主要阳离子。盐分与钙（Ca）和镁（Mg）密切相关。氯（Cl）、硫（SO）、K、Na 和碳酸氢盐（HCO）反映了岳普湖县土壤盐渍化程度。变渗透性带中的粘土层极大地阻碍了包气带中的水盐运动。从西向东，粘土层变厚变浅，阻碍了向下的水运动，增加了盐分淋洗的难度。此外，灌溉制度也影响了包气带中的水盐运动。在相同的土壤结构下，较高水通量的洪水灌溉导致盐分淋洗更显著，灌溉水中总溶解固体（TDS）越低，越有利于有效盐分淋洗。总之，我们的研究结果为改善和管理当地盐渍土提供了理论基础，并指导了合理的农业灌溉实践。
