覆膜开孔条件下盐渍土壤的潜水蒸发及水盐运移特性

为研究地下水浅埋区不同覆膜开孔率盐碱土的潜水蒸发和水盐运动情况，在室内进行了土柱蒸发模拟试验(地下水埋深50 cm)。结果表明，与不覆膜相比，覆膜可显著降低潜水蒸发强度、减少潜水累积蒸发量，同时也有效减少了盐分在土表的积累量。蒸发结束时，开孔率分别为3.24%、9.97%和20.27%的潜水累积蒸发量与裸土相比分别减少了79.87%、74.19%和77.93%，土层深度5 cm范围内土壤电导率分别降低了36.93%、34.41%和35.16%，即覆膜开孔率的差异对盐分累积的影响小于对潜水蒸发的影响。三种处理中，9.97%开孔率的土表积盐量和潜水蒸发量均相对较大。随着蒸发历时的增加，不同处理土壤含水量剖面的变化相对较小，但潜水蒸发强度却有所降低，这与蒸发过程中盐壳形成后反过来又抑制了潜水蒸发有关。其次，覆膜阻滞不同盐离子表聚的效果不同，其中Cl^-表聚作用受开孔率影响较大，而Na⁺和SO₄^2-表聚作用受开孔率影响不大。

Characteristics of groundwater evaporation and water-salt transport in saline soil under different opening ratios of film

The indoor simulating experiment of evaporation was carried out in soil columns to observe the behaviors of groundwater evaporation and water-salt movement in saline soil in shallow water-table zone under different opening ratios of film. The results showed that film mulching could significantly inhibit the groundwater evaporation and reduce the salt accumulation on the soil surface compared with no plastic mulching. Under the condition of 3.24%, 9.97% and 20.27% opening ratios, the accumulated groundwater evaporation was reduced by 79.87%, 74.17% and 77.93% respectively, and the conductivity of soil solution was reduced by 33.18%, 22.70%, and 25.57% respectively, in contrast with the control at the end of the ten days. Therefore, the influence of mulching to groundwater evaporation was more obvious than to salt accumulation. Among these three opening ratios, the treatment of 9.97% caused relatively high salt accumulation on the soil surface and large groundwater evaporation. The moisture content in soil profile kept relatively stable, but the groundwater evaporation intensity decreased with the increase of time for different opening ratios, which could be attributed to that the salt crusts in soil surface were developed in the initial evaporation phase and they in return inhibited the water evaporation. The effect of opening ratios on salt movement was different for various ions, in which, the accumulation of Cl^- was influenced more remarkably by opening ratios than that of Na⁺ and SO₄^2-.