Thursday, 10 November 2005 - 9:15 AM
323-4

Evaluation of an Integrated Wireless Irrigation Control System for Variable Rate Water Application.

Jose Chavez, Francis Pierce, Gary Matthews, and Todd Elliott. Washington State University, WA St.Univ-Irr Ag Res. & ExCtr, 24106 N. Bunn Rd, Prosser, WA 99350-8694

By design, a precision irrigation system offers precise monitoring and control of irrigation water application but may be subject to inherent errors that affect performance. Our objective was to evaluate the performance of a new integrated wireless system to monitor and control all aspects of a sprinkler irrigation system remotely and in real time. Briefly, the system varies water application rate by pulsing nozzles controlled by solenoids connected via relays to a single board computer. The system monitors all aspects of the irrigation system and any sensors installed in the soil or crop. The system was installed on two spans of a linear move irrigation system at the WSU Irrigated Agriculture Research and Extension Center in Central Washington. The field was planted to spring barley. Four irrigation patterns were imposed on 30m x 36 m blocks including uniform, linear increasing, linear decreasing, and quadratic with irrigation rates applied as a percentage of nozzle nominal application rate at 10 psi. Nozzles were spaced 3.0 m apart and each nozzle controlled separately and pulsed to create the intended irrigation patterns. Standard catch can studies were performed during the growing season and after harvest. Soil water content was measured either with sensors reporting 15 minute data or gravimetrically periodically. The system performance was evaluated in terms of on-time maps, application uniformity relative to the application design, and spatial variation in soil water content. The coefficient of uniformity of the linear move system was accounted for in the catch can data analysis. Pre-harvest catch can studies showed application errors to be within 5%.

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