Effects of soil initial water content on line-source infiltration characteristic in moistube irrigation
Zhang Jun1,2,3, Niu Wenquan1,3, Zhang Linlin3, Shi Liyan1, Wu Zeguang1
1.Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China; 2.Shaanxi Land Construction Group, Xi′an, Shaanxi 710075, China; 3.Institute of Soil and Water Conservation, CAS & MWR, Yangling, Shaanxi 712100, China)〓〓〓〓
In order to identify effects of soil initial water content on line-source infiltration characteristics in moistube irrigation, the wetting front advance distance and soil moisture variation feature were investigated through indoor simulation experiments for isotropic soil under four initial water contents: 2.1%, 5.6%, 8.0% and 10.1%. The experimental results revealed that soil initial water content had a great effect on line-source infiltration, the advance speed of wetting front and surface wetting time were raised and extended with increasing initial water content, and could be presented by a power function of irrigation time. Meanwhile, the shape of wetting soil was slightly affected by initial water content and its cross-section shape was kept to be nearly circular. During an irrigation event, the cumulative infiltration and average infiltration rate were positively correlated with initial water content, but the time for a stable infiltration rate was negatively related to the content. The water content inside a wetting soil body was distributed concentrically, and the moisture gradient was decreased with increasing initial water content, however, the uniformity coefficient of moistube-irrigation was increased with the content.Those results may be useful for application of moistube-irrigation.
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