Abstract: A center pivot irrigation system adapted for variable depth application of water under the corner sprinkler arm. The system includes a pivot sprinkler arm with a first set of nozzles, and a first set of control valves each provided on the pivot sprinkler arm upstream of a nozzle. The irrigation system includes a corner sprinkler arm pivotally coupled to an end of the pivot sprinkler arm, and the corner sprinkler arm includes a second set of spaced apart nozzles and a second set of control valves. The irrigation system includes a controller transmitting control signals to the first and second sets of control valves to open and close in a pattern that includes a valve pulsing pattern for the corner sprinkler arm, whereby input water is applied at a variable rate under the corner sprinkler arm to apply different depths to various user-defined zones.

Abstract: A center pivot irrigation system is described that includes a controller that makes use of a particular flow rate of input water to deliver differing or variable depths of irrigation to two or more user-defined areas under a pivot irrigator. The controller operates to pulse control valves for the nozzles/sprinkler heads on and off as the sprinkler arm rotates. The valve pattern along the span of the sprinkler arm is chosen during each operating cycle such that the total water flow through all the open valves matches the flow rate of the input or supply water to the pivot irrigator. To ensure the variable application depth, the speed may be changed during valve duty cycles. A farmer may define an irrigation plan that defines the variable rate irrigation (VRI) zones and also defines exclusion or no spray zones in which no irrigation should occur.