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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #329799

Title: Automated support tool for variable rate irrigation prescriptions

item NGUYEN, ANH - University Of Missouri
item THOMPSON, ALLEN - University Of Missouri
item Sudduth, Kenneth - Ken
item Vories, Earl

Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/3/2016
Publication Date: 7/31/2016
Citation: Nguyen, A.T., Thompson, A.L., Sudduth, K.A., Vories, E.D. 2016. Automated support tool for variable rate irrigation prescriptions. In: International Conference on Precision Agriculture Proceedings, July 31-August 3, 2016, St. Louis, Missouri. Available:

Interpretive Summary: Variable rate irrigation (VRI) technology allows changing the prescribed amount of water as an irrigation machine moves across a field. As with other variable rate applications such as fertilizer, physical limitations of the machine mean that the actual application rate changes will differ from prescribed rate changes, and that the physical characteristics of the irrigation machine (e.g., center pivot) need to be considered in developing an application plan. In previous research, we developed a computer program that could automate creation of such application plans. In this study, the previously developed program was updated with new capabilities. It was enhanced by removing the need to look up certain parameter values from tables. It was also modified to handle fertigation, or the application of fertilizer through the irrigation machine. The results from this study will provide irrigation engineers with an improved tool to optimize VRI prescriptions with respect to system operating characteristics.

Technical Abstract: Variable rate irrigation (VRI) enables center pivot management to better meet non-uniform water and fertility needs. This is accomplished through correctly matching system water application with spatial and temporal variability within the field. A computer program was modified to accommodate GIS data layers of grid-based field soil texture properties and fertility needs in making management decisions. The program can automatically develop a variable rate application prescription along the lateral for the entire field based on soil texture, slope, water, and crop chemigation needs, with the goal to improve production while making better use of water and fertilizer. Prescriptions could be developed for VRI using individual sprinkler control, defined sprinkler zones, or system rotation speed changes. Results are presented for a specific field showing: 1) automatic determination of the maximum application depth based on each respective application rate along the lateral matched to the soil intake rate at each position; and 2) the corresponding prescription maps for variable rate chemigation for three types of VRI control. The program outputs management prescriptions in both text format and graphically to enable growers to visually assess the results. Future work will be directed at converting management prescriptions into a format directly usable by pivot control panels.