Experimental Studies On Saline Water Utilization

Based on the review of national and international research results of slight saline water utilization , combined with the National 863 Project "the study on the safety and effective use of slight saline water and regeneration water", a salt water irrigation test was carried out to analyze salt-water transfer and its effect on crop physiological process and yields through the theoretical analysis and indoor and field experiment method. The results were as follows:1. On the basis of saline water infiltration, the characteristics of movement of soil water and salt under different cumulative infiltration were studied .The results indicated that when the salinity of the infiltration water was 3g/l, the top soil was desalinized and salt accumulated at the wetting front. Though the desalinized depth was different under different cumulative infiltration, the ratio of desalinized depth and wetting front distance was about 0.342 and the ratio of desalinized depth and cumulative infiltration was 0.862 .2. The salinity of the infiltration water greatly influenced the characteristics of soil water and salt movement. The results indicated that the higher the salinity of infiltration water was, the faster cumulative infiltration and wetting front increased, and more salt accumulated at the wetting front. When the saline water(<3g/l) infiltrated to 45cm, the top soil of 0-37cm was desalinized, when the saline water of 3g/l infiltrated, the desalinized depth was 0-15cm. Moreover, SAR of top soil increased with the SAR of the infiltration water.3.Through lab experiment, the characteristics of soil water and salt movement under different initial soil moisture content were analyzed . The results showed that the lower initial soil moisture content was, the less infiltration occurred and wetting front moved slowly, and soil salt were leached more efficiently. At the same time, salt reduced in the top soil and salt accumulated at the wetting front.4. Through field experiment, the effect of different irrigation quota on soil water and salt movement was studied under saline water irrigation. The suitable irrigation system were further discussed. The results indicated that the higher irrigation quota was, the higher soil moisture content and the lower soil salt concentration was. But the total salt content increased evidently. Considering the water use efficiency, salt balance and crops water requirement as a whole, the suitable quota of salt water irrigation was 120 m3/667m2. The quota at elongation, earing and milking period was 50 m3/667m2, 40m3/667m2 and 30m3/667m2.5. Through field experiment, the impact of different salinity of the irrigation water on soil water and salt movement were studied. The results indicated that even if there was different at initial soil condition, such as initial moisture content and initial salt content, salt content in soil profile and SAR at top soil increased greatly after the high salinity water infiltrated. The ESP of soil rose from 7 to 14, 15 and 17 after the salt water whose salinity was2.6g/l (SAR=12) 3.6g/l (SAR=18) 4.2g/l (SAR=23) irrigated. The high salinity water led to the increase of the solution concentration and the crop yields drop.6. Through field experiment, the impact of different irrigation order of saline and fresh water on soil water and salt movement were studied. The results made clear that soil salt increased after saline water infiltration and decreased after fresh water infiltration. The yield of winter wheat went down as the times of the saline water irrigation increased. If the times of the saline water irrigation was same, the saline water irrigated at the prophase of crop growth, the crop yields was lower.