SABI Magazine Volume 9 Issue 3 | Page 14

Centre pivots – case study

Close Spacing LEPA Applicators

Improve Irrigation Efficiency

By John Maurer and Dan Schueler *
Summary
Close Spacing irrigation with LEPA( Low Energy Precision Application) applicators can save water, reduce energy consumption, and increase yields by providing more available water to plants at lower pressures. Following successful results in 2015 on the Triple D Ranch in Dyer, Nevada USA, comparison testing was initiated to obtain more information.
In 2016, testing was initiated on alternating spans of moving deflector sprinklers and Senninger LDNs with LEPA pads and Shrouds in order monitor the effects of both sprinklers. Moving deflector sprinklers were installed at 120-inch spacing. LEPA applicators were installed at 30 to 40 inch( 76 to 101.6 cm) spacing.
The LEPA applicators provided more water to the plants. This could be attributed to the reduced energy of the water making it more resistant to wind drift and evaporation. Low pressure operation provided additional savings in the form of reduced energy required to pump the water. In addition, the close spacing of the LEPA sprinkler heads greatly diminished burrowing varmint damage to fields by creating an undesirable habitat.
Background
Triple D Ranch is located in Dyer, Nevada USA( Longitude: 118.01, Latitude: 37.615) in Esmeralda County. Elevation is 4898 feet( 1492.9 metres) and the climate is windy with little to no rainfall and very low humidity. The primary soil type is heavy silt clay loam. The ranch encompasses 4,600 overall
acres( 1861.5 overall hectares) with 52 centre pivots over alfalfa. Thirty-seven centre pivots irrigate with LEPA applicators excluding two test machines.
Area water table levels are declining in this area, which led farm managers to investigating ways to reduce water use and still retain successful yield levels.
Exposure to Close Spacing LEPA irrigation practices at the World Ag Expo led farm managers to additional independent research. This included information about the success of LEPA in Texas dating back to the 80’ s and renewed interest in the practice, as well as recent university studies.
The managers of Triple D Ranch
investigated different product options recommended by the Texas Senninger Irrigation District Manager, secured product samples and tested several combinations. After this investigation, they settled on the Senninger LDN with a single pad equipped with the CM1 insert and Shroud at 10 psi( 0.69 bar). They converted two machines in
Image 1. Triple D Ranch is located in Dyer Nevada( Longitude: 118.01, Latitude: 37.615) in Esmeralda County.
Image 2. LEPA applicators were at close spacing of 30-inches, 18-inch height, with 10-psi pressure regulators.
Image 3. LEPA applicators demonstrated increased irrigation efficiency by making more water available for plants.
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SABI | FEBRUARY / MARCH 2017