地下滴灌条件下土壤水能态研究

Distribution of soil water potential energy under subsurface drip irrigation

研究灌水器与土壤界面处的能态是研究地下滴灌土壤水分运动的关键之一。该文通过理论和试验相结合的方法,探讨了地下滴灌土壤水势的分布状况。结果表明:根据灌水器的流量和土壤的导水性之间的关系,将其分为两种情况,在灌水器流量不大于土壤扩散能力时,灌水器出口处的土壤水势等于该处的土壤吸力,为非正压状态;否则,灌水器出口处的土壤水势为正。理论分析和室内试验结果均表明,对同一土壤,影响地下滴灌土壤水势分布的主要因素是灌水器的额定流量和土壤初始含水率,在一定的流量范围内,灌水器出口的稳定正压随灌水器流量的增大而增加,随土壤初始含水率的增大而降低。在此基础上,提出地下滴灌条件下土壤水势分布的近似计算式,并简要分析了这一特殊土壤水分分布对地下滴灌系统的影响。

The research on the state of soil water potential adjacent to emitters（SWPAE）is the key to study soil water movement under subsurface drip irrigation（SDI）.Distribution of soil water potential energy under SDI was studied by theoretical analyses and tests.The results showed that there were two kinds of SWPAE according to the relationship between emitter flow and soil water conductivity.The SWPAE equaled to the soil suction,which was negative,when emitter flow was not larger than the capacity of soil water diffusion.Otherwise,it was positive.Both theoretical analyses and tests showed that SWPAE was mainly decided by emitter rated flow and the initial soil water content in the same soil.Under a certain range of emitter flow,SWPAE increased with the increasing of emitter flow,while it would decrease with the increasing of the initial soil water content.On the basis,formulas were built to calculate the distribution of soil water potential under SDI,and effects of distribution of soil water potential on SDI system were brief analyzed.