Irrigation Rain Sensors Accuracy

In recent years, an increasing number of municipalities throughout the country have implemented mandates, rebates and/or cost-saving programs for the use of rain sensors (RSs). The objectives of this research were to evaluate two expanding disk RS types, Mini-Click (MC) and Wireless Rain-Click (WL), with respect to: a) the accuracy of their set point with respect to rainfall depth, b) the number of times in irrigation bypass mode, and c) the duration in irrigation bypass mode. For the MC treatments, rainfall set points of 3, 6, and 13 mm were established. Rain sensor models were monitored from 1 January 2006 to 31 July 2007, except for MC set at 6 mm which was monitored starting on 13 September 2006. The 576-day experimental period had rainfall frequency and cumulative amount below a historical year. The number of times that replicate units within a treatment switched to bypass mode tended to behave the same through time, for treatments WL and 3-MC, which ranged from 64 to 78 events and from 57 to 68 events, respectively. Treatment 6-MC was the most consistent between replicates, where three units switched to bypass mode on 39 occasions, and one unit did it on 34 times. Replicates from treatment 13-MC showed the most variable behavior, shutting off between 50 to 29 times. On average, treatment WL shut off after 2.8 mm of rain. Because this model does not have a specific set point, accuracy could not be calculated. Accuracies for the other treatments resulted in 73% for 3-MC, 30% for 6-MC, and 58% for 13-MC. Treatments WL, 3-MC, 6-MC, and 13-MC, remained in bypass mode 82, 80, 64, and 83% of the time, respectively, for less than 24 h.