The Comparison of Vertical Soil Water Distribution under Surface-Drip Irrigation and Subsurface-Flood Irrigation

Due to decreasing water resources and increasing irrigation interval in gardens, implementation of modern irrigation systems such as under-pressure irrigation is necessary. But the main concern is the effects of changing traditional irrigation systems to under-pressure irrigation systems from the point of view of supplying water needs of old trees and temporal variations of soil characteristics. In this study, two methods of subsurface-flood irrigation and surface-drip irrigation were implemented in Yazd Agricultural and Natural Resources Research and Education Center. The soil water content was monitored during the experimental period (18 May 2019 to 10 January 2020) by installing TDR probes in three soil depths of 15, 30 and 60 cm for each irrigation method with three replications. The results showed that soil water content at the soil depths of 15 cm and 30 cm were higher for surface-drip irrigation as compared to the subsurface-flood irrigation at the end of the irrigation interval. Two days after irrigation, the effects of subsurface-flood irrigation on soil moisture distribution became apparent at the deep layers of the soil, such a way that soil water content at the soil depth of 60 cm was higher for subsurface-flood than surface-drip irrigation. The measuring of the soil water content at the soil depth of 60 cm in subsurface-flood irrigation showed that the irrigation interval could be increased about 9 days as compared to the surface- drip irrigation. However, because of applying water below the soil surface for the subsurface- flood irrigation, the salinity increment occurred at surface soil.