Irrigation water planning for crops in the central highlands of Ethiopia, aided by FAO CROP WAT MODEL

Information on crop water requirement of crops is vital for irrigation water planning. In the central parts of Ethiopia, agriculture has solely been dependent on rain-fed until recent time that irrigation for vegetable production is becoming one activity for crop production. However, irrigation practice in terms of the amount of water to be used and frequency of application has lacked proper knowledge. The purpose of this study is therefore to deliver the preliminary information on seasonal water requirement of different crops based on the widely used FAO crop wat model. The lowest values of reference evapotranspiration were observed for Akaki, followed by Debere Zeit, Alemtena and Modjo. Accordingly, the results showed Onion requires frequent application of irrigation followed by tomato while wheat needs longer interval that in all the sites. The seasonal net irrigation application for Onion (60%field efficiency) is 2890, 2920, 3870, 3840 m3 for Debre Zeit, Akaki, Modjo, and Alem-Tena with their respective orders. Tomato requires net application of irrigation amount, 4650, 4030, and 5560, 4720 m3/ha for the sites, Debre Zeit, Akaki, Modjo and Alemtena respectively. Similarly, at Debre Zeit, Chickpea needs 3000 cubic meter per hectare while wheat requires 3670 m3 of irrigation water. Key words: Crop water requirement, field efficiency, irrigation frequency, FAO CROP WAT 8.1