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