Effect of Deficit Irrigation on Soybean (Glycine max L.) Under Conventional, Fixed and Alternate Furrow Irrigation Systems at Jimma, Ethiopia

Irrigation water supplies are decreasing in many areas of the Ethiopian regions, which is requiring many farmers to consider deficit-irrigating soybean (Glycine max L.). This study investigated the response of soybean (Glycine max L.) to moisture deficit under conventional, alternate and fixed furrow irrigation system over a three years period. A field experiment was conducted at Jimma Agricultural Research. A randomized complete block design (RCBD) with three replications was used. nine treatments which combined and imposed at all growth stages were used. The three years combined result indicated that there were a highly significant (P<0.01) variation among treatments for grain yield, above ground dry biomass yield and water productivity. The grain yield of soybean was significantly (P<0.01) affected due to moisture stress imposed at different growth stages. Accordingly, the highest grain yield was obtained from conventional furrow 100% ETc irrigating all growth stage treatment followed by conventional furrow 75% ETc and alternate furrow 100% ETc. The highest water productivity of 1.23 kg m-3 was obtained from alternate irrigation system at 50 ETc but the yield loss is not tolerable. Alternate furrow 100% ETc and conventional furrow 50% ETc gave a better yield with high water productivity. Therefore, for better water productivity without a significant yield loss, it is recommended to use alternate furrow irrigation with 100% ETc and conventional furrow irrigation 50% ETc. In addition, if the water resource is not scarce in the area, it is recommended to use conventional furrow irrigation with 100% ETc throughout the whole growth stage to obtain optimum yield. Keywords: Water productivity, Deficit irrigation, ETc, Furrow irrigation system, Soybea