Soil water movement under a drip irrigation double-point source

Particularly in dry regions, the scarcity of high-quality fresh water has heightened the importance of urban runoff water re-use, leading as well to the improvement of water use efficiency through the surface drip irrigation method. Given the limited research on wetting front migration under a surface drip irrigation emitter, soil water movement under a double-point-source irrigation emitter was investigated. An experimental soil bin was designed and filled with silt loam soil, and time domain reflectometry and tensiometers were used to measure soil moisture contents and soil water potential, respectively. The results show that under the conditions of 6 hours of irrigation with two drippers each delivering 1.05 L hr⁻¹ and spaced at 45 cm, the soil moisture content of the 0–30 cm layer increased rapidly and reached 0.29 cm³ cm⁻³, and was greater than that in the 30–60 cm layer as irrigation proceeded. After 6 hours the irrigation was stopped, such that in the redistribution phase, soil moisture of the top layer gradually decreased, while that of the sublayer gradually increased. The results indicate that 6 hours of irrigation under given emitter flow conditions produced adequate soil moisture down to 30 cm for most shallow-rooted crops.