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Variable Rate Irrigation Management for Humid Climates Using a Conventional Center Pivot System

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  5th National Decennial Irrigation Conference Proceedings, 5-8 December 2010, Phoenix Convention Center, Phoenix, Arizona USA  IRR10-9849.(doi:10.13031/2013.35858)
Authors:   Allen L Thompson, Kenneth A Sudduth, Joseph C Henggeler, Earl D Vories, Andrew D Rackers
Keywords:   irrigation scheduling, soil texture, variable rate irrigation

This study investigates suitability of a standard commercial center pivot system for variable-rate water application under Mid-South conditions. The objective was to determine if field variability data can be applied to conventional moving sprinkler systems to optimize irrigation management on non-uniform soils. Data have been collected using a three tower pivot with overhead spray nozzles located at the University of Missouri Delta Center. Treatments include rainfed and irrigation sets of 8 to 46 mm in approximately 8 mm increments with total annual irrigation depth less than 190 mm. Irrigation scheduling was based on the Arkansas Scheduler method. Corn yields and IWUE are presented for all treatments for the first year of study. Soil texture varied from less than 20% to greater than 90% sand in the same field. Data were analyzed using Proc-GLM for yield by treatment and texture based on over 2400 averaged yield monitor observations. Although rainfall was timely throughout the growing season, irrigated yields were significantly greater than rainfed (Pr >95%) for all treatments. Average yields were greatest for soils with percent sand between 46 and 62% with lowest average yields for soil textures greater than 74% sand. The greatest average yield over all texture classes was for an application depth per set of 15 mm. Increased irrigation depth per set (31 mm and greater) favored heavier textured soils (i.e. low sand content). Soil textures on either extreme were more problematic for irrigation scheduling, with the highest sand content being the most sensitive.

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