A Mobile Sprinkler Test Carriage to Evaluate the Suitability of LEPA and LESA at New Sites

Abstract

Abstract. It has been shown that lowering the elevation of the sprinklers on center pivots increases application efficiency and significantly decreases the pumping power requirements since they operate at lower pressures. Low Elevation Spray Application (LESA) therefore saves both water and energy, and, because more of the irrigation water reaches the soil, crop yield and quality are generally higher. However, several of the early (1980‘s) Low Energy Precision Application (LEPA) trials in the Pacific Northwest resulted in excessive runoff and the trials were abandoned. A light-weight, portable, moving sprinkler infiltrometer was developed to assess the potential for runoff under varying soil texture, slope, surface roughness and crop residue conditions to identify conditions where LESA technology could be used and to develop recommendations for conditions where its use should be avoided. The equipment design allows sprinkler type, spacing and height and ground speed to be easily changed. Since the equipment must be operated to simulate water application under the outer span of a pivot, drop hoses of varying length allow sprinklers with nozzle size found on the outer-most pivot span to be attached. Speed of movement across (or up/down) the test area can be varied by use of an electronic timer controlling a cable winch to best match outer tower speed. Convenient connection of pressure regulator / sprinkler body assemblies allows easy testing of different sprinkler types to assess the impact of sprinkler type on infiltration and runoff.