Low-elevation spray application (LESA) is modified from the typical sprinkler head configuration (mid-elevation spray application, MESA) on pivot irrigation systems. As its name implies, LESA places nozzles close to the ground. The lower elevation of nozzles in LESA reduces water losses to wind drift and evaporation, especially in windy areas such as Rexburg, Idaho. The decreased elevation also reduces the sprinkler drop energy on the ground and thus the occurrence of runoff in fields.
Due to the reduced elevation, system operating pressure is reduced in LESA, which could reduce pumping costs per season compared with MESA. LESA systems have been successfully adapted in crops such as timothy hay, alfalfa, grass seed, beans, mint, silage corn, barley and wheat.
In the 2017growing season, adjacent spans of LESA and conventional MESA sprinkler mounting were tested on two potato fields in Rexburg and Rupert, Idaho. Tuber yield under LESA was 453 and 554 hundredweight per acre in Rexburg and Rupert, respectively; 451 and 423 hundredweight per acre under MESA. However, tuber yield was not statistically different between LESA and MESA in either location. Tuber-specific gravity was not affected by irrigation methods either. Soil water tension under the two irrigation systems exhibited similar trends during the season. A LESA system may be comparative to MESA in tuber yield and soil moisture, but long-term research is need to confirm the benefits of LESA in potato production.
Comparisons between MESA and LESA in Rexburg and Rexburg, Idaho
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MESA
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LESA
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Nozzle height above ground
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6 feet
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1 foot
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Wind drift and evaporation
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High
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Low
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Irrigation uniformity
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Medium to low
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Medium to high
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Irrigation efficiency
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85%*
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92%
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System operating pressure
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40 to 60 PSI
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25 to 35 PSI
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Outlet spacing
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10 to 20 feet
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4 to 5 feet
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*Under no-wind or low-wind conditions. Measured values under wind speeds typical of southern Idaho would typically be in the 65 to 75 percent range.
Xi Liang and Rui Yang are researchers at the University of Idaho Aberdeen Research and Extension Center. Howard Neibling is an associate professor at the UI Kimberly R&E Center. Yi Wang, formerly stationed at the Kimberly R&E Center, is currently with the Department of Horticulture at the University of Wisconsin-Madison. Xin Qiao is an assistant professor of irrigation and engineering at the University of Nebraska’s Panhandle R&E Center.