Determination of Irrigation Interval and Optimum Water Demand of Wheat at Eastern Hararghe zone of Oromia

Soil moisture based application of irrigation water is crucial for obtaining optimum irrigation scheduling of crop. The objectives of this study were determining optimum irrigation interval, irrigation frequency and optimum water demand of wheat for better production. The result indicates that maximum irrigation frequency and maximum irrigation water was applied by 60% ASMDL. Minimum irrigation frequency and minimum water was applied by 140% ASMDL treatment. A narrow irrigation interval was applied by 60% ASMDL and elongated irrigation interval was applied by 140% ASMDL. The result show that, maximum plant height, number of productive tillers, straw yield and grain yield was obtained by 60% ASMDL treatment. The result indicates that, statistically there is no significance difference between 80% ASMDL and 60% ASMDL treatments in terms of wheat grain yield. The result implies that, as irrigation water is applied more frequently and in short interval the wheat produce more tiller which leads to maximum grain yield. Maximum water productivity (2.078 kg/m3) was obtained by scheduling irrigation at 100% ASMDL. Statistically there is no significance difference between 80% ASMDL and 100% ASMDL in terms of water productivity. Minimum water productivity was obtained by scheduling irrigation at 140% ASMDL. The result show that, optimum grain yield (41.69 qt/ha) and optimum water productivity (2.001 kg/m3) was obtained by scheduling irrigation at 80% ASMDL treatment than others. The lowest grain wheat yield (26.44 qt/ha) and lowest water productivity (1.716 kg/ha) was obtained by scheduling irrigation at 140% ASMDL treatment. Therefore, scheduling irrigation at 80% ASMDL (at p=0.4) has been recommended for wheat with 5 day, 7 day, 5 day and 12 day irrigation interval at initial, development, mid and maturity stage of wheat respectively in the study area and same agro-ecology.