Emitter uniformity and application efficiency for centre-pivot irrigation systems

Abstract

A significant portion of the intensively cultivated agricultural areas in the Southern Great Plains of the USA is located in the Texas High Plains. Agriculture in this region mainly depends on water from the vast underground Ogallala Aquifer. Due to excess withdrawal and a slow recharge process, groundwater levels are declining in many areas of the aquifer. Recently, regulations have been enacted in the Texas High Plains for restricting the amount of water pumped from the Ogallala Aquifer. In addition to pumping restrictions, conserving water by promoting irrigation systems with high application efficiency is also a priority. We investigated the emitted uniformity and application efficiency of 14 centre-pivot irrigation systems in the Texas High Plains. Application efficiencies were in the range of 60-70% for mid-elevation spray application (MESA) systems, 70-80% for low-elevation spray application (LESA) systems, and greater than 90% for low-energy precision application (LEPA) systems. Correction of the small number of defective emitters per system would not realize significant water savings. However, water savings could be realized by switching from MESA or LESA to LEPA, assuming the choice of crop allowed it.