Arega Mulu and Dr.Tena Alamirew
The main objective of irrigation is to apply the optimum amount of water to the crop root zone that the crop needs for development and which cannot be provided by rains. When irrigation systems are used to apply fertilizers and pesticides, application uniformity becomes even more critical. Consequently, it is important for center pivot owners and operators to periodically check the uniformity of their systems. Therefore, the main objective of this study was evaluating the coefficient of uniformity for center pivot sprinkler irrigation in order to address the potential of uniform irrigation application using center pivot sprinkler irrigation. The uniformity of water application under a center pivot is determined by setting out 24 catch cans with a 9 cm opening diameter and 11.5 cm height located along a line extending radially from the point 70 meter away from the center of the pivot at 2 m spacing between each can, bringing the irrigation system up to proper operating pressure, and letting the system pass over them. The discharge of the system is measured by using measuring gauges .Record the distance from the center of the pivot and the amount of water collected for each can. This weighing can be done by multiplying the amount of water observed in every catch by either the distance from the center pivot or in number of location. From this information, a coefficient of uniformity can be calculated and usually expressed as a percentage. Results from the field evaluation and calculated using Christiansen Coefficient of Uniformity (CU) was 91.3%, which is very good.