土壤质地和灌水器材料对负压灌溉出水流量及土壤水运移的影响

负压灌溉法是一种新近提出的节水灌溉技术，灌溉时供水水头为“负值”，即灌溉水源高程低于灌水器高程。不同材料灌水器和土壤质地是影响灌溉系统出水流量及土壤水运移的重要因素。该文研究了在高程差H为-0.5 m情况下两种灌水器及两种质地土壤对两者的影响。结果表明：灌水器相同时，累计入渗量、水平和垂直最大湿润距离随时间呈幂函数关系变化；在历时相同时黏壤土较砂壤土大；湿润体近似为六分之一的竖直椭球体，但黏壤土水平与垂直最大湿润距离之比大于砂壤土。土壤质地相同时，纤维灌水器较陶土灌水器出水流量高。试验结果进一步证明了负压灌溉的可行性，并为确定负压灌溉系统应用范围及规划设计过程中灌水器选择提供了依据。

Effects of soil textures and emitter material on the soil water movement and efficiency of negatively pressurized irrigation system

Negatively pressurized irrigation(NPI) method, a newly irrigation technology, in which the elevation of the emitters is higher than that of the water source, runs under negative hydraulic head. The emitter materials and soil textures are important factors in the water movements in soils and the flux of NPI system. A series laboratory experiments were arranged to study the effects of the two factors on the NPI with emitters 0.5 m above the water source. Fibrous emitters and ceramic emitters were used in the experiments as water application emitters to investigate the water movements in a clay loamy soil and a sandy loam. The results show that the relationships between time and cumulative infiltration, the maximum horizontal and vertical wetted distances are power functions, but the values of the clay loamy soil are bigger than those of the sandy loam during the same period with the same emitter. The wetting fronts are almost ellipsoid-shaped. The ratio of the maximum wetted distance in the horizontal to that in the vertical direction in the clay loamy soil, is bigger than that in the sand loam. The flux of NPI system with fibrous emitters is higher than that with ceramic emitters under the same soil texture. The results are useful for selecting emitters for the design and determining the application range of NPI system.