Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2005
Publication Date: 11/1/2005
Citation: King, B.A., Wall, R.W., Kincaid, D.C., Westermann, D.T. 2005. Field testing of a variable rate sprinkler and control system for site-specific water and nutrient application. Applied Engineering in Agriculture. 21(5):847-853. Interpretive Summary: Site-specific irrigation management to apply water according to crop water use and soil properties requires the ability to control amount and rate of water applications across time and space. Center pivot and linear-move irrigation systems provide a platform upon which to test site-specific irrigation management technologies. The objective of this study was test a newly designed variable flow rate sprinkler attached to a linear-move sprinkler irrigation system for water and chemical application uniformity under field conditions. The test showed that water applications over a 40% to 100% application rate range were within 5% of the target rate with uniformities over 90%. Measured nitrogen application rates were within 4% of the targeted rate across the water application rate range. These results show that technologies are available to develop and manufacture sprinkler irrigation equipment capable of applying variable amounts of water and chemicals in precision agricultural production systems.
Technical Abstract: Development and implementation of site-specific sprinkler irrigation management has been limited due to the lack of variable rate sprinklers. Thirty-two prototype variable rate sprinklers were constructed and field tested on a three-span linear-move irrigation system. An algorithm was developed for a distributed control network to allow each sprinkler to be individually controlled in groups of six or seven along the linear-move lateral. Water applications uniformity was monitored over a 36% to 100% range in application rate. Measured application uniformity equaled or exceeded 90%. Variable rate nitrogen application was monitored over a 1.1-ha area. Measured nitrogen application rate was within 4% of the target application rate. Results indicate that the prototype variable rate sprinkler and control system allows water and chemical application to vary over a 36% to 100% range in application rate with minimal effect on water application uniformity.