More than 10,000 miles of underground pipeline have been installed within the High Plains Underground Water Conservation District No. 1 service area to reduce water losses caused by deep percolation and evaporation from open, unlined earthen ditches. Studies by the Water District indicated water losses of 10 to 30 % per each 1,000 feet of ditch. The total water loss per foot of ditch in a 2,000 hour irrigation season averages about 5,000 gallons of water.
CENTER PIVOT SYSTEMS
High-pressure above-line discharge center pivot sprinkler systems had an irrigation application efficiency of about 60 %. Wind drift and evaporation losses equaled about 40 %. The High Plains Water District has worked with agricultural researchers, producers, and manufacturers to convert these systems to partial dropline or full dropline LEPA center pivot systems. As a result, very few of the high-pressure systems are in operation today.
The partial dropline center pivot discharges water between the top of the pivot and the ground. The irrigation application efficiency of this type of system is about 80 %. Wind drift and evaporation losses are about 20 % of the water pumped.
LEPA CENTER PIVOT SYSTEMS
A center pivot system, equipped with full drops, is known as a Low Energy Precision Application (LEPA) system. This system can achieve irrigation application efficiencies of up to 95 %. Since water is applied at low pressure in the furrow, wind drift and evaporation losses are virtually eliminated. As a result, only five % of the water pumped through the system is lost. Most irrigators use furrow dikes and/or chiseling in the furrow beneath the LEPA system to maximize the uniform water application.
When added to a conventional furrow irrigation system, a time-controlled surge valve can eliminate irrigation tailwater losses, minimize deep percolation losses, and reduce the length of time that water in the furrow is exposed to evaporation. Water savings from 10 to 40 % have been measured after the addition of surge valves to conventional furrow irrigation systems.
In drip irrigation, buried lines and emitters are used to apply slow, frequent applications of water to the soil directly surrounding plant roots. Water losses caused by evaporation, deep percolation, and runoff are virtually eliminated. Drip irrigation can save as much as 30 to 40 % of the water required by some other types of irrigation to provide the plants with an equal amount of water.
In response to producer interest in the latest irrigation technology, the High Plains Water District has installed a drip irrigation demonstration plot in Deaf Smith County, Texas. These demonstration plots are installed to give area producers the opportunity to learn more about drip irrigation and how to use it in crop production. Previous sites have been installed in Hockley, Lubbock, and Lynn Counties.
SOIL MOISTURE MONITORING
Soil moisture monitoring is a simple, cost-effective technique producers can use to improve their irrigation water management. Soil moisture monitoring devices, such as gypsum blocks and resistance meters, and tensiometers, help producers determine how much water they need to apply during an irrigation to fill the root zone soil profile. This reduces the likelihood of applying too much or too little water.
The formation of small earthen dams in the furrow helps conserve precipitation or irrigation water that would otherwise run off the field. Water collected in the furrow dikes is held in place until it can soak into the soil.