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Abstract The study aim to evaluate subsurface trickle irrigation system as related to emitter discharge and infiltration soil when the discharge of a subsurface emitter becomes larger than the soil infiltration intake creating back pressure from soil on emitter flow. One goal of the study is to assess the performance of subsurface trickle irrigation SSDI comparing with surface trickle irrigation SDI. To achieve this objectives 1- Measured emitter flow rates and their correspondent pressure head along trickle lateral at selected emitter outlets of both SSDI and SDI for 2, 4, 8 and 16 l/h emitter flow rate at 100 and 150 kPa inlet pressures 2- Tested the emitters in terms of manufacturing and hydraulic variations for SSDI and SDI. A field experiment was conducted for 50 m of lateral length (φ13.6 mm inner diameter), and with 100 turbulent flow path emitters which connected to lateral by connector between them micro-tube φ4 mm inner diameter in zero slope level. In addition, emitter spacing was 0.5 m, and the inlet pressures head were 100 and 150 kPa. Several points were taken into consideration, such as emitter characteristic friction loss, manufacturing variation, flow rate and hydraulic variation. A comparison study between the flow rates of emitters in surface trickle irrigation (SDI) and other subsurface trickle irrigation (SSDI) in which emitters were buried at 20 cm from soil surface. For given initial soil moisture content and emitter flow rate, soil wetted area under the emitter for clay and sandy clay loam soils with two different hydraulic properties were plotted. Results showed that pressure head and flow variation along lateral decreased by increasing both emitter flow rate and inlet pressure. A higher soil back pressure is developed where the emitter flow is high. The values of irrigation uniformity of subsurface trickle irrigation were greater than it’s values in the case of surface trickle. Flow variation along lateral increased in surface trickle lateral than subsurface trickle lateral. Also field results showed that horizontal and vertical water movements were related to both emitter flow rate and soil intake rates. Soil moisture content was contoured directly after irrigation and soil-water redistribution. |