It is called a Low Energy Precision Application (LEPA) center-pivot system. Instead of high-power spray units, this system has small water sprayers hanging down from a large water-carrying pipe above. At the bottom of each pipe, very close to the ground, is a nozzle that gently sprays water onto the crops.
Because the nozzle is so close to the ground, you lose a lot less water to evaporation than you would with a traditional spray-irrigation system. Plus, electricity is saved because it takes less to use these low-powered systems. These systems allow more than 90-percent of the water pumped to be used by the crop — pretty efficient!