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针对黄淮海冲积平原土壤剖面中粘土夹层普遍存在的现象,在典型易盐渍区开展模拟易盐农田常规种植条件下水盐运移的大型土柱实验,基于长达20年的长系列监测数据分析,系统研究易盐渍区不同土体构型和地下水位等代表性条件下的土壤水盐运移规律和粘土夹层的影响特征。研究结果表明:粘土层有良好的保水和隔盐能力,尤其对表土积盐的抑制效果显著,且抑盐效果随粘土层厚度增加而提升;含粘土夹层土体表土积盐的地下水埋深范围更小,表土积盐高峰出现在1 m左右地下水埋深,全剖面粉砂壤土土体的表土积盐高峰出现在1.5 m左右地下水埋深、且地下水埋深小于阈值2.5 m时极易引发盐渍害;粘土夹层对土壤盐分运移有双重影响,在其可抑制表土积盐的同时,粘土层部位易积盐,水土资源利用过程中需监测和防控其次生盐渍化风险。
In view of the ubiquitous phenomenon of clay intercalation in the soil profile of the alluvial plain in the Huang-Huai-Hai region, a large soil column experiment was carried out to simulate the movement of water and salt under conventional salt-saline farmland cultivation in a typical salt-prone area. Based on a long series of monitoring data , Systematically studied the soil water and salt transport laws and the characteristics of clay intercalations under different soil structures and groundwater levels in the salinization area. The results show that: the clay layer has a good ability of retaining water and separating salt, especially for the inhibition effect of topsoil, and the salt suppression effect increases with the increase of the clay layer thickness. The range of groundwater depth of topsoil with clay intercalated soil The peak value of the smaller and topsoil salt appeared at about 1 m groundwater depth. The topsoil salt peak of the silty loamy soil and soil in the whole section appeared at about 1.5 m groundwater depth and the groundwater depth was less than 2.5 m, The clay interbed has a dual impact on soil salinization. While it can restrain salt accumulation in the topsoil, it is easy to accumulate salt in the clay layer. Therefore, the risk of secondary salinization should be monitored and controlled during the utilization of soil and water resources.