Submitted to: International Conference on Water Resources Engineering Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 9, 1999
Publication Date: N/A
Technical Abstract: Interest in site-specific management of crop inputs such as water and fertilizers has increased during the past few years, primarily because of the availability of yield monitors, which permit farmers to directly observe the effect of varying inputs on crop yield. A commercial center pivot irrigation system was modified in 1995 to provide site-specific water rand fertilizer applications to areas as small as 100 m**2. The modified system was used to manage applications during 1995-1998 while the reliability of the control system was improved. A second center pivot, located on a site with widely variable soils, was modified in a similar manner in 1998. In 1999, both modified systems were used to determine the effects of a range of water and N-fertilizer application rates on corn growth and yield. Measured soil water values indicate good spatial accuracy in irrigation delivery, good uniformity within the management zones, and a distinct range of soil water contents caused by various irrigation application rates. Once crop production effects of variable inputs, soils, and economic factors have been determined, site-specific irrigation and N-fertilizer combinations can be developed for soil management zones.