Validation of irrigation scheduling for cultivation of irrigated wheat in semi-arid climatic condition of Ethiopia

ABSTRACTThis study was conducted for three years (2014-2016) to validate irrigation scheduling of irrigated wheat cultivation to determine appropriate irrigation regime. The experiments were irrigation scheduling based on CROPWAT Model 8.0 and validation on field trial. The treatments were arranged in randomized complete block design with three replications. The field trial was involving three irrigation regime treatments were used for comparison. The treatments were Treatment 1 (T1): Optimal irrigation regime as determined by Cowpat for windows that provides irrigation water of D1=50mm at an interval of I1=7 days, Treatment 2(T2): Optimal irrigation regime as determined by Cowpat for windows that provides irrigation water of D2=67mm at an interval of I2=10 days. Treatment 3(T3): Optimal irrigation regime as determined by Cowpat for windows that provides irrigation water of D3=108.3mm at an interval of I3=15 days. Treatment 4(T4): An irrigation regime that provides irrigation water at critical soil moisture depletion and an amount that would refill the soil moisture depletion to field capacity. Result indicated that grain yield was significantly affected by irrigation levels. Irrigation regime of Treatment 4 produced higher grain yield 2400 kg/ha and 20.0q/ha in 2015 and 2016 cropping season. The highest mean yield of wheat (2200 kg/ha) was obtained from critical moisture refill field capacity irrigation application. Whereas, the lowest mean yield (1778 kg/ha) was obtained from T3, 7 days irrigation interval and 50mm irrigation application. This indicates that yield of wheat decrease with decreasing water amount and short interval frequency. Irrigation scheduling based on cowpat model with irrigation regime that provides irrigation water at critical soil moisture depletion and an amount that would refill the soil moisture depletion to field capacity found promising optimum wheat scheduling under Werer and similar areas.