微咸水微润灌溉下土壤水盐运移特性研究

为探明土壤水分和盐分在利用微咸水进行微润灌溉条件下的运移情况,采用室内土箱模拟试验方式,设置2.0、2.5、3.0、3.5、5.0 g/L 5种不同矿化度处理,以蒸馏水处理作对照,共入渗72 h。结果表明:入渗结束时在不同方向上的最大运移距离随矿化度增大呈先增大后减小趋势,在3.0 g/L处理下达到最大值,且微咸水处理的湿润锋运移距离均大于蒸馏水处理;将累积入渗量代入Kostiakov入渗公式,入渗系数随矿化度的增大呈先增大后减小趋势,入渗指数不断减小;土壤电导率以微润带为轴心向四周不断增大,在湿润锋处达到最大值,脱盐区与湿润体形状相关,呈圆环状分布;入渗结束后土壤剖面平均含盐量与蒸馏水处理之间无显著性差异,脱盐半径随矿化度的增大呈线性递减趋势;利用微润灌进行灌溉,土壤盐分存在表聚和底聚现象,且表层积盐更为严重。

Characteristics of Water and Salt Movement in Soil under Moistube-irrigation with Brackish Water

In order to explore the movement characteristics of water and salt in soil under moistube-irrgation with brackish water, an indoor soil box simulation experiment was conducted under five different mineralization degree treatments with distilled water as control in 72h. The results showed that with the rise of mineralization degree, the maximum migration distance presented a trend of first increase and then decrease in different directions and reached the highest when the degree of mineralization was 3.0g/L. And the distances of wetted front under treatments of brackish water were all greater than that of distilled water. Then the cumulative infiltration was substituted into the Kostiakov infiltration equation and the infiltration coefficient showed a trend of rise first and then fall with the increase of mineralization degree, while infiltration index continued to decline. The soil conductivity was increased constantly to all around with the moistube-irrgation zone as axis and reached the peak at the wet front. The desalting area was related to the shape of the wetted body and distributed in circular shape. There was no significant difference in the average salt content of soil profile between brackish and distilled water after infiltration. The desalination radius was decreased linearly with the increase of mineralization degree. Both surface and bottom convergence phenomenon existed and the salification in soil surface was more serious under moistube-irrgation.