不同初始土壤含水率和滴头流量下滴灌土壤湿润体特征及其有效性评价

【目的】研究滴灌条件下土壤湿润体水分分布。【方法】开展单点源入渗试验,探究了不同初始土壤含水率和滴头流量对滴灌土壤湿润体特征及湿润体内含水率分布的影响。【结果】灌溉结束24 h后,湿润体内的含水率达到相对稳定的状态,湿润体体积基本保持稳定;随灌水及再分布时间增加,湿润体宽深比逐渐降低,再分布过程中,宽深比随初始含水率减小而增大,随滴灌流量减小而减小;各处理湿润体体积与入渗时间呈良好的线性函数关系,灌水结束24 h后,各处理实际湿润体积均已超出计划湿润体积;计划湿润体内含水率60%θFC～80%θFC区间占比随初始含水率增大而减小,随滴头流量的增大而增大,其余各区间占比变化规律与之相反,相同滴头流量下,50%θFC初始含水率处理超出计划湿润体的体积最少。【结论】再分布后的湿润体体积主要受灌水量的影响,可以选择较小的初始含水率及较大的滴头流量以提高湿润体内水分有效性。

Effects of Different Initial Water Content and Dripper Discharge on Wetted Body Characteristic of Drip Irrigation

【Objective】The aim is to explore the effect of different initial water content and dripper discharge on the characteristics of wetted body under drip irrigation and moisture distribution in the wetted body.【Method】A single point-source infiltration experiment was conducted to investigate the variations on characteristics value of wetted body during irrigation and water redistribution.【Result】After 24 h of irrigation, the water content in the wetted body reached a relative stable state, and the volume of the wetted body remained stable. As the time of irrigation and water redistribution increase, the width-to-depth ratio of wetted body gradually decreased. During the water redistribution, the width-to-depth ratio of wetted body increased with the decrease of initial water content,and decreased with the decrease of dripper discharge. The volume of wetted body showed a good linear variation with infiltration time, the actual volume of the wetted body was larger than that of planned wetted body after 24 h of irrigation. In the planned wetted body the proportion of water content interval in 60%θFC～80%θFCdecreased as the initial water content increased and increased as the dripper discharge increased, the variations on the remaining intervals was opposite. Under the same dripper discharge, the volume of the 50%θFCinitial water content treatment beyond the planned wetted body was the least.【Conclusion】The volume of the wetted body after redistribution is mainly affected by the irrigation amount, a smaller initial water content and a larger dripper discharge can be selected to improve the moisture effectiveness in the wetted body.