Testing Low Energy Spray Application (LESA) in the Pacific Northwest

Abstract

Abstract. Low Energy Precision Application (LEPA) and Low Energy Spray Application (LESA) involve lowering the elevation of the sprinklers on center pivots or linear move irrigaiton systems. It has been shown that these increase application efficiency and that it significantly decreases the pumping power requirements since they operate at lower pressures. Because of this, LESA saves water, saves energy, and because more of the irrigation water reaches the soil crops can get better yields and quality. Because of several trials in the Pacific Northwest that resulted in excessive runoff, opinions were soured to this technology. One span of an existing pivot was converted to LESA on six different pivots in Nevada, Idaho, and Washington. It was tried in alfalfa, mint, grass seed, beans, wheat, oats, and silage corn. It worked well with no to minimal runoff in every condition. All of the farmers expressed enthusiasm for the technology and plans to convert entire pivots to LESA. The spray heads were placed at 12 inches from the soil surface, and the spacing was less than or equal to 5 ft apart. Soil moisture sensors at multiple depths in both the LESA and MESA portions of the pivot were compared. The data clearly demonstrate that the LESA was much more efficient and more water reached the soil. It worked well with the sprinkler heads below the top of the canopy even in tall crops like corn. Although LESA is not universally applicable to all sites and soils, it conserves significant amounts of water and energy and benefits growers. It is under-utilized in the Pacific Northwest, and throughout many western states.