两种覆盖方式下的土壤溶液盐分含量变化

利用定期取表层土样测定其电导率和在不同深度埋设盐分传感器探头的方法，在作物生长季节内，监测了秸杆覆盖和地膜覆盖农田不同深度的土壤溶液含盐量变化。结果为：（1）土壤表层盐分含量和10cm深土壤溶液含盐量的变化规律为，未灌水期间迅速增加；灌水时急剧降低。秸杆覆盖和覆膜可明显抑制盐分的累积，使整个生育期内土壤盐分含量波动幅度变小。其中覆膜处理抑制土壤盐分累积的作用最大。（2）30cm深土壤溶液含盐量的变化为灌水降低，未灌水时升高。秸杆覆盖处理在灌头水后含盐量虽有波动，但总体上呈下降趋势；覆膜处理在灌头水后一直处于很低的含盐水平。（3）60cm深土壤溶液含盐量变化幅度小于其上土层。秸杆覆盖增强了灌水对60cm土壤溶液含盐量的降低作用，并抑制了后期土壤溶液含盐量增加。覆膜减少了灌水对60cm深土壤溶液含盐量的降低幅度，也抑制了未灌水期间含盐量的增加。

VARIATION OF SALT CONTENT IN SOIL SOLUTION IN FARMLAND COVERED BY PLASTIC FILM OR WHEAT STRAW

Soil salinity sensors were used in the field plot experiments to monitor the salinity variation of soil solution at different depths. The field plot experiments were carried out in the farmland covered by plastic film, wheat straw and uncovered. The results are as follows: (1) The salinity increases sharply during the period without irrigation but reduces quickly during irrigation in both surface soil and soil solution 10 cm deep from the top. The variation of salt content is relatively smooth in the farmland covered by plastic film or wheat straw comparing with that in the uncovered farmland. (2) The salinity of soil solution 30 cm deep from the top also increases during the period without irrigation but reduces during irrigation. However, it reduces in the farmland covered by wheat straw after the first irrigation, and reduces slowly and keeps a low level after the first irrigation in the farmland covered by plastic film. (3) The salinity variation of soil solution 60 cm deep from the top is gentler than that of the overlying soil layers. The salinity of soil solution of this layer in farmland covered by straw reduces more sharply than that in formland covered by plastic film and the uncovered farmland during irrigation but increases more slowly during the period without irrigation.