Center Pivot Irrigation System Modification to Provide Variable Water Application Depths

A multiple-segment water application system was developed and attached to a commercial center pivotirrigation system to provide variable application depths within each segment at a given speed. Each segment was 9.15 m(30 ft) long and consisted of three parallel manifolds sized to provide 1x, 2x, and 4x, where x is a minimum applicationdepth. The three manifolds could be operated individually or in various combinations to provide eight application rates(0-7x) at any given tower velocity. Water application depth varied from 0 to 12.4 mm (0 to 0.5 in.) when the center pivotwas moving at 50% of full speed. Water was delivered via industrial, full-cone, and wide angle spray nozzles that were selected to provide the desiredrange of application depths for the entire length of the pivot. The irrigated areas for each angular increment were small atthe pivot end of the system and required nozzles with small discharge rates while at the distal end the areas were largerrequired nozzles with larger discharge rates. Agricultural chemicals, especially nutrients, that can be injected into theirrigation water may also be applied at the same range of rates provided the chemical concentration is constant.