灌溉条件下黄土层的水盐效应研究

Effects of irrigation on water and salt in loess layer

通过灌溉试验配合施尿素,钻探采取土样并对岩土浸提液电导率进行测定,研究了灌溉和施肥条件下非饱和黄土层的水流入渗规律和盐分变化特征。结果表明,黄土层中非饱和水入渗具有明显的含水量峰值带,其运移速度在0～6m的埋深带约为15～17cm/d,同时存在快速的超渗导管流;含盐量为615.82和815.07mg/L的灌溉水配合施尿素454.6和378.8kg/hm2的宽畦漫灌,可使上部6m黄土层电导率显著增加,最大点电导率增幅在黄土原区为2.12倍,在阶地区达4倍以上,表明灌溉水中的盐分、化肥的离解和灌溉入渗水流对黄土层的溶滤与淋洗作用,会显著影响黄土超根层盐分分布、运移和氮沉降。

The water infiltration and salt change characteristics were studied by irrigation experiments,urea application and soil sampling,and the electricconductivity of soil maceration extract was analyzed.The results showed that the peak value belt occurred in unsaturated water infiltration,and the movement rate was 0.15-0.17 m/d in 0-6 m layer,at the same time,quickly tube water flow also occurred in this layer.The electric conductivity increased significantly,and the biggest increase was 2.12 times in loess plateau area and 4 times in loess terrace area when the salt content in the irrigation amount was 615.82 mg/L and 815.07 mg/L,respectively,and urea application rate was 454.6 kg/hm2 and 378.8 kg/hm2.These results indicated the following factors,such as salt in irrigation water,inos produced in fertilizers,chemical materials stems from dissolution and leaching of irrigation water in loess influence the salt distribution and movement and nitrogen subside in loess layer under root belt.