初始含水率对土壤垂直线源入渗特征的影响

为解决现有渗灌系统在深根系植物应用中存在的问题，该文设计了一种垂直线源灌水器，并通过室内土箱试验研究了不同初始含水率条件下砂黄土和塿土的垂直线源入渗特征。结果表明：Philip入渗公式的形式能够较好地描述2种土壤的三维入渗过程；入渗时间一定时，砂黄土和塿土的累积入渗量均与初始含水率之间呈二次函数递减关系；2种土壤入渗的最大径向距离、最大垂向距离、宽深比均与初始含水率之间呈二次函数抛物线关系；2种土壤相比，偏砂性的砂黄土累积入渗量在低初始含水率下较塿土大，但随着初始含水率的增加其减小速度较塿土快，偏黏重的塿土入渗临界初始含水率较砂黄土大，但其入渗范围较砂黄土小。这些结果可为不同土壤条件下的垂直线源灌水技术发展提供参考。

Effect of initial water content on vertical line-source infiltration characteristics of soil

For solving the problem presented in the application of infiltration irrigation system in deep rooted plants, a vertical infiltration irrigation device was proposed. Experiments about vertical line-source infiltration characteristics of sand loess and lou soil with different initial soil water contents were carried out in laboratory with this device. The results showed that the three-dimensional infiltration processes for the two soils could be described well by revised Philip infiltration equation. For a given time, there was a negatively quadratic function relationship between accumulative infiltration and initial water content for sand loess and lou soil. The maximum horizontal distance, vertical distance, and horizontal-vertical ratio of the two soils had quadratic parabola relations with initial water content. Comparison of the two soils indicated that the accumulative infiltration of sand loess with more sand particles was greater than that of lou soil under lower initial water content. With the increasing of initial water content, reduction speed of the accumulative infiltration of sand loess was faster than that of lou soil. The critical initial water content of lou soil with more clay particles was higher than that of sand loess, but its infiltration range was lower than that of sand loess. The results could provide some guidelines for vertical line-source irrigation technology in different soils.