Effect of Deficit Irrigation Levels at Different Growth Stages on Onion Yield and Water Productivity Under Furrow Irrigation Method, Silte Zone, Ethiopia

Abstract

Water scarcity is the most severe constraint for agricultural growth in arid and semi-arid areas. To overcome this, there is a need to use the scarce water efficiently and economically which is an important strategy to address present and future water need. This study was conducted for two years in Misrak Azernet Berbere Woreda starting 2017/18 to investigate the effect of defict irrigation levels at different growth stages on yield and water productivity of onion. The experiment has nine deficit irrigation levels as a treatment including control treatment and were laid out in randomized completed block design with three replication. The results indicated that deficit irrigation levels at different growth stages had significantly (p<0.05)) affected the yield and yield water productivity of onion. The highest marketable yield (28.68ton/ha) was obtained from 20% deficit irrigation at late stage whereas lowest yield (14.42 ton/ha) was recorded from 40% deficit irrigation in all growth stages.Treatment 9,2,6 and 8 have no statistically significant difference on yield. The highest water productive (8.77 kg/m³) was obtained from treatment 2 (20% deficit irrigation throughout the season). The lowest marginal rate of return(5.17birr) was obtained from treatment (20% at developmentstage (40% deficit irrigation at mid stage and 20% at late stage). These results confirmed that with deficit irrigation practice it is possible to increase water productivity by saving water and increase income from scarce water. Therefore, it was recommended that applying at 20% deficit irrigation of crop water requirement throughout season in four days irrigation interval is beneficial for obtaining optimum onion yield and increases water productive. The farmers should also use treatment (20% at developmentstage /40% at mid stage and 20% at late stage) deficit irrigation of crop water requirement to save scarce irrigation water and to gained better economic return as optional.