Abstract

This study evaluated the wetting patterns around drip and subsurface irrigation systems (DI and SI), respectively with three irrigation scheduling techniques. The drip and subsurface irrigation systems were used to irrigate a tomato crop. The wetting patterns for each irrigation system and each irrigation scheduling technique was evaluated below the soil surface at different distances and depths from the emitter 24 and 48 h after irrigation. The soil moisture distribution patterns showed that the vertical movement of soil moisture was higher than the horizontal movement under both DI and SI systems. The overall wetted area, delimited by the wetting front was largest for the manually controlled irrigation scheduling with both DI and SI, and smallest for the Smart controller irrigation scheduling under both DI and SI systems. The effect of irrigation scheduling techniques on the water distribution pattern varied at different soil depths. Average coefficients of uniformity values for the DI and SI systems were 84.32 and 88.72%, respectively. The coefficients of uniformity for SI were higher by approximately 4.40% than for DI for all irrigation scheduling techniques, although there was variation in Cus values between the DI and SI systems with all three techniques. It can be concluded that a parameter related to the soil water content is an important consideration in estimation of soil wetting patterns with both DI and SI systems. The results of this research can be used in the design, operation, and management of DI and SI systems.

Key words: Drip irrigation; subsurface irrigation; Soil water; Wetting pattern; coefficient of uniformity, Irrigation scheduling techniques.