CaCl2溶液灌溉对土壤水盐与斥水性分布的影响

选用砂土和盐碱土并添加斥水剂,采用0、1、3和6g/L的CaCl2溶液进行室内土柱入渗试验,对比灌水水质对土壤水盐及斥水性分布的影响。结果表明:咸水灌溉后,砂土1和亲水盐碱土的累积入渗量、湿润锋和入渗率曲线均较光滑;而砂土2和斥水盐碱土的入渗特征曲线不如砂土1的光滑,入渗过程比前者慢得多。灌水矿化度增加对盐碱土的入渗过程影响更明显。Philip模型与Kostiakov公式拟合亲水土壤入渗率过程都较好。砂土1和砂土2在咸水灌溉后剖面的滴水穿透时间都比初始值有所增加,但最大增加值仅3.6 s。盐碱土灌后剖面的滴水穿透时间增加明显,最大增加值为19 s。灌水矿化度增加对电导率、Ca2+质量浓度和Cl-质量浓度分布均有影响。研究表明咸水灌溉不仅影响水盐分布,而且对斥水性也有不同程度的影响。

Effects of CaCl2 Solution Irrigation on Distributions of Soil Water, Salt and Water Repellency

Saline water irrigation is one of the effective measures for relieving the crisis of agricultural water utilization. Sand and saline-alkali soils were selected and were added with hydrophobic materials. CaCl2 solution with mineral degrees of 0, 1, 3 and 6 g/L were used for laboratory column infiltration experiments, in order to compare the effects of irrigation water quality on the distributions of soil water, soil salt and soil water repellency. The results showed that the curves of cumulative infiltration, wetting front and infiltration rate for sand 1 and wettable saline-alkali soil were all smooth after saline water irrigation. But those for sand 2 and hydrophobic saline-alkali soil were not so smooth, and their infiltration process were much slower than those of sand 1 and wettable saline-alkali soil. The increase of irrigation water mineral degree affected the infiltration process of saline-alkali soil more than that of sand. Philip model and Kostiakov equation were both good for fitting the infiltration curves of wettable soils. After saline water irrigation, the water drop penetration time (WDPT) along the profile increased both for sand 1 and san 2, but the maximal increment was only 3.6 s. The increment of WDPT for saline-alkali soil was obvious and the maximal increment value was 19 s. The increase of irrigation mineral degrees affected electrical conductivity, concentration of Ca2+ and concengtration of Cl-. In conclusion, this study indicated that saline water irrigation affected not only the distributions of soil water and salt, but also that of hydrophobicity.