A second catchment system will provide water samples to facilitate evaporation estimates using Method 2 and will consist of cylindrical glass jars containing a small quantity of mineral oil. Collected water will accumulate in the tube during the irrigation event and will be transferred to plastic collection bottles at the conclusion of the event. A total of ten equally spaced 8 cm diameter holes will be drilled on one side of the tube and will serve as the ports to collect irrigation water. The first system will consist of 1.5 m lengths of 10 cm diameter PVC pipe that are sealed on both ends with end caps. Two forms of catchment systems will be deployed to collect irrigation water reaching the surface-one for each estimation method. Method 2 will use a volumetric approach wherein evaporation is estimated as the difference between the volume of water dispensed by the irrigation system (Vi) and the volume of water collected in catch cans(Vs). Evaporation (E) is estimated using: E=(ECs-ECi)/ECi. Method 1 will estimate evaporation by making measurements of the electrical conductivity of the water entering the irrigation system (at meter ECi) and water that reaches collection systems placed on the ground (ECs). Project Methods Evaporation during irrigation events (E) will be assessed using two methods. The research outlined in this proposal will establish field studies that 1) quantify these spray evaporation and drift losses from pressurized turf irrigation systems and 2) develop meteorological models to predict the magnitude of these losses. Two components of irrigation efficiency - evaporation of water while in transit from the irrigation head to the ground (spray evaporation) and drift of liquid water off target (to non-turfed areas) will play a critical role in determining whether Arizona's water duties provide adequate water for the proper culture of turfgrass. A recent evaluation of the Arizona turf water duties suggests the duties may force turf facilities in the Phoenix and Tucson areas to utilize deficit irrigation regimes that could eventually lead to problems with soil salinity. In Arizona, turf facilities that irrigate with groundwater and maintain more than 4 ha of turfgrass must comply with water duties that restrict the amount of water that can be used for irrigation. Many DSW states are now limiting the amount of water that can be used to irrigate turf in an effort to encourage conservation.
Irrigation is required to sustain the turf areas of the DSW because the bulk of the region is classified as arid or semi-arid. Non Technical Summary The amount of land area planted to turfgrass is growing rapidly in the Desert Southwest (DSW) as population growth and tourism increase the demand for more golf courses, parks and schools.