Kansas Center Pivot Uniformity Evaluation Overview

Abstract. Center pivot irrigation systems are the most common system type in Kansas for a variety of factors – one of which is the ability to deliver a uniform depth of water application for a variety of crops and field conditions. Uniform applications are dependent on properly designed, installed and operated sprinkler nozzle packages. Uniformity evaluations were conducted as part of the Mobile Irrigation Lab (MIL) project to promote adoption of improved irrigation management practices with an emphasis on ET based irrigation scheduling. Since efficient and uniform water applications are critical to successful irrigation scheduling; MIL assessment included evaluation of sprinkler package performance using a single line catch can test. Catch can data was used to calculate the coefficient of uniformity (CU) and average application depth. The average CU value of the tested systems was 78.7 with a range of from 91.9 to 53.2. Many of the factors affecting pivot uniformity could have been identified and corrected with a visual inspection and/or comparison to the manufacturer‘s sprinkler design specifications. Some of the catch tests indicated poorly designed and/or maintained sprinkler systems with reduced uniformity directly impacting crop performance, water use efficiency and economic results. Initial information was used in extension programs to illustrate the effect of various correctable sprinkler package deficiencies on performance and to encourage irrigation farmers to examine their nozzle packages and operating conditions.