INTEGRATION OF SUBSURFACE IRRIGATION AND ORGANIC MULCHING WITH DEFICIT IRRIGATION TO INCREASE WATER USE EFFICIENCY OF DRIP IRRIGATION

Abstract

This study aimed to integrate the ability of organic mulching (rice straw) and subsurface irrigation with deficit irrigation to save soil moisture content (SMC) and increase water use efficiency (WUE). A field experiment was carried out during 2019 on tomato crop in sandy soil. The variables included four levels of irrigation namely 70, 80, 90, and 100% of crop evapotranspiration (ETc) with three irrigation techniques which were subsurface drip irrigation (SSD), mulched surface drip irrigation (MD), and mulched subsurface drip irrigation (MSSD). The treatments of MSSD showed earlier maturity of tomato crop and longer picking period if compared to MD and SSD treatments. MSSD showed higher ability to save (SMC) than other irrigation techniques. Reduction of applied water from 100 to 70% ETc led to a decrease in tomato yield by 23.32% at MSSD compared to 28.47%, and 26.23% for MD, and SSD respectively. The highest WUE was at MSSD70 with 5.92 kg/m3 while the least was 4.21 kg/m3 with SSD100. The highest benefit/cost ratio was 9.03 with the treatment SSD70 while the highest profit of water unit was 2.19 US$/m3 with MSSD70. MSSD can be used with 90% of ETc without any significant difference in tomato crop while it can be used with 70% ETc to obtain higher WUE. The study recommended integrating rice straw mulching and subsurface drip irrigation with deficit irrigation as a strategy to save irrigation water and obtain the maximum possible benefits of water unit whether related to tomato yield or its revenue.