The Soil Water Physical Properties in the Tarim Desert Highway Shelterbelt Under Saline Water Drip-irrigation

The soil water characteristic curves for different depths from 0cm to 150 cm of the soil profiles in Tarim desert highway shelterbelt were measured by Pressure Membrane Apparatus and fitted by van Genuchten,then the soil physical water properties for different depths were analyzed and revealed.The results showed as follows:(1)It was significant to imitate the soil water characteristic curves for different depths in this study area with the help of van Genuchten Model,because all the results of RMSE between simulated values and measured values of soil water content had reached remarkable levels which were not more than 0.01.(2)From strong to weak,the capacity of soil water retention for different depths were followed respectively by 0-5cm,40-60 cm,100-150 cm,60-100 cm,5-40 cm while the soil water supply were followed respectively by 5-40 cm,60-100 cm,0-5cm,40-60 cm,100-150 cm,and it took on a strong water supply under the soil suction on Pressure which was less than 1.5×105 Pa.The available moisture content of soil was decreased gradually from the upper depth to the lower depth and its average was17.286%.(3)Saturated moisture capacity,capillary moisture capacity and field moisture capacity were also showed a synchronized decreasing trend from the upper depth to the lower depth;on the other hand,the relationship was closed between three kinds of soil moisture holding-capacity and soil bulk,which was consistent with one-linear regression function.(4)The upper limit of available water was the soil moisture content corresponding to the suction of 0.3×105 Pa and it was suitable to take 1.5×105 Pa as the boundary point ofsuction for readily available water and resistant available water.The readily available water content in all the depths were more than the resistant available water content,and the value of former was 13.127%,which was three times of the latter.Compared with the others,the readily available water content in the depths of5-40 cm and 60-100 cm took the most supreme proportion while the resistant available water content in the depths of 5-40 cm and 60-100 cm took the highest proportion in the range of available soil water content,and both the values of them were the biggest.Besides,the bigger the proportion of readily available water content,the weaker the capacity of soil water retention in the same depth.