渗灌管首末端压力与茶树根区土壤水分运移关系

为探明渗灌条件下渗灌管首末端压力与土壤水分运移之间的关系,设置了3个试验小区进行不同灌水流量和灌水持续时间的试验.通过连续定点观测茶树根区(纵向30 cm深,横向30 cm宽)土壤含水率的变化和渗灌管首末端灌水压力,研究了渗灌管不同首末端压力下土壤水分运移的变化规律.研究表明:灌水前土壤含水率不仅影响土壤入渗能力,而且决定着土壤水分运移方向;渗灌管首末端压力累积值与灌水持续时间呈线性关系,当茶树根区土壤含水率达到田间持水量时,累积曲线斜率发生突变,可以利用累积曲线斜率发生突变时的灌水持续时间作为控制充分灌水(100%田间持水量)的临界值,避免土壤水分无效渗漏.该研究为渗灌系统控制灌水持续时间及研发智能化渗灌灌溉系统提供了一种参考方法.

Relationship between subsurface seepage pipe pressure and soil water movement at tea root zone

In order to investigate the relationship between the pressure at both ends of a subsurface seepage pipe and the soil water movement under sinfiltration irrigation, experiments were carried out by testing different irrigation flow rates and irrigation durations. By continuously monitoring the changes in soil moisture content in the root zones of tea trees(30 cm in the vertical direction and 30 cm in the horizontal direction of the soil moisture monitoring profile)and the pressure at both ends of the subsurface seepage pipe, the soil water movement under different pressures at both ends of the subsurface seepage pipe was examined. The results show that soil water content before irrigation influences the infiltration capacity, and impacts the direction of soil water movement. The cumulative pressure at both ends of the subsurface seepage pipe shows a linear relationship with irrigation duration. The slope of the cumulative pressure curve changes suddenly when the soil moisture content reaches the field capacity at the tea root zone. It is found that the duration of irrigation at the time of abrupt change in slope of the cumulative pressure curve can be used as a critical value for controlling the full irrigation(100% field capacity), thereby avoiding the loss of soil water in deep percolation. The study provides a reasonable reference method for rational control of irrigation duration.