Comparative Loss Study of Four Different Sprinkler Packages on Center Pivot Systems under South Georgia Conditions

Abstract

The efficiency of water use from irrigation systems is influenced by temperature, wind,humidity, and solar radiation. Accepted values for water loss efficiency are the results ofyears of tests; however, most of these values do not take areas of high relative humidityinto account. The actual losses of water under different conditions are a critical componentof proposed cost share programs for water conservation with agricultural irrigation. Thepotential benefits of these different sprinkler packages require real world results underactual field conditions. This information can be passed on to farmers so they can obtainbetter use of the water they are pumping.<br><br>Since center pivot irrigation represents a large percentage of the irrigation systems in thestate of Georgia [over 344 000 ha (850,000 ac)], the potential water conservation benefitsfrom changing to more efficient sprinkler packages is one aspect of the conservationinitiative. The main objective of this research was to determine and compare water losses incenter pivot systems due to the evaporation and wind interference. In order to determine anappropriate location along the center pivot boom where the tests should be run, uniformitytests were developed and conducted for two months. After this process, the loss tests wereconducted during different times of the day in varying weather conditions.<br><br>This paper includes the procedures used and the initial results from the first season of theloss evaluations. Results show the variability on the average water catch among sprinklerpackages as well as the difference of average collections for atmospheric conditions. Initialresults indicate a 10% increase in losses when the relative humidity is low (40 to 70%) ascompared to a relative humidity between 71 and 99%. Using spray nozzles on top of thepivot boom resulted in the lowest losses within the relative humidity tests, followed byspray nozzles on drops (an additional 6% loss), high angle impact sprinklers (additional16% loss) and low angle impact sprinklers (additional 22% loss). Additional data isrequired to determine if the added cost for drops with spray nozzles on center pivotirrigation systems are justified for water conservation in humid areas.