SOIL MOISTURE SENSOR IRRIGATION CONTROLLERS AND RECLAIMED WATER; PART II: RESIDENTIAL EVALUATION

Water savings potential of soil moisture sensor irrigation control technologies have not been reported in homes irrigating with reclaimed water (RW). The main objective of this research was to evaluate the performance and water conservation potential of a soil moisture sensor system (SMS) in homes that used RW as their source for irrigation, as compared to homes with irrigation timers only, or to homes with educational materials and/or rain sensors. Secondary objectives were to: a) estimate the water depth applied by the different technologies compared to a theoretical requirement (calculated using a daily soil water balance), and b) estimate the effects of local watering restrictions on the amount of RW used by homeowners. In the vicinity of Palm Harbor, Florida, a total of 64 homes supplied with reclaimed water for irrigation (with an average salinity of 0.7 dS/m) were selected for this study. Dedicated irrigation flowmeters were installed in every home. The 64 homes were divided in 4 treatments with 16 homes each. Treatments were: MO (monitored only), SMS, rain sensor, and rain sensor plus educational materials. The SMS treatment was the only group of homes significantly different to MO, reducing the average number of irrigation events per week (1.7 vs. 2.7 events/week, respectively), decreasing the depth of the weekly irrigation (22 vs. 42 mm, respectively), and applying 44% less water, over the 32 months of data collection. These results indicate that the tested SMS can save a significant amount of RW, compared to the other methods/technologies investigated. Even when all treatments over-irrigated most of the time, SMS irrigated most properly, compared to a theoretical requirement. Finally, under severe dry weather conditions, the local watering restrictions promoted a more efficient use of the RW.