滴灌条件下土壤水分再分布过程研究

对均质风干砂壤土在滴灌条件下水分再分布过程进行研究发现:距离供水滴头较近的点,水分再分布过程开始后该点土壤含水量突然下降1~2个百分点,随后该点土壤含水量随时间延长而减少,前期较快,后期变缓;原湿润锋边缘处各点的土壤含水量在再分布过程前期表现为继续增加,后期则随时间的延长而缓慢减少。土壤水分的再分布运动使得湿润体内的土壤含水量均有不同程度的下降,土壤水分由高含水区向低含水区运移。在试验条件下水平湿润锋增长幅度6%,垂直方向增长幅度为9%,垂直方向大于水平方向;灌溉结束24 h后土壤水分运动达到暂时的平衡,此后土壤含水量变化很小,土壤湿润锋几乎不再扩展。

Investigation on soil water redistribution under drip irrigation condition

The test was carried out on air-dried sandy soil to investigate the course of soil water redistribution under drip irrigation condition. It was discovered that the water content at the spot that was close to the dripping points dropped by 1%-2% suddenly after the course of water redistribution began. Afterwards, the soil water content of this spot reduced along with the time, and it reduced quickly in the earlier period, but slowly in the later period. The water content Of the original wetting front edge continued to increase in the earlier period of soil water redistribution, but reduced slowly along with the time in the later period. The movement of soil water redistribution enabled the soil water content in the wetting region to drop to some extent, and the soil water was shifted from high moisture section to low moisture section. Under the experiment condition, the horizontal wetting distance grew up by 6 %, and the vertical wetting distance grew up by 9 %. The movement of soil water achieved the temporary balance in 24 h after stopping irrigation. Subsequently the change of the soil water content became very small, and the wetting front was kept nearly un-expanded.