SMRT-Y Soil Moisture Sensor Kit Turns any controller into a smart controller The Rain Bird SMRT-Y Soil Moisture Sensor kit adds closed-loop feedback to irrigation systems, conserving water through on-off system control based on digital measurement of the soil’s volumetric water content. How It Works: The sensor takes soil moisture readings every 10 minutes. When the sensor detects dry conditions prior to the normal watering cycle, that cycle is allowed. When the soil moisture is above the set threshold, the watering cycle is suspended to avoid wasting water. Operating Principle When soil moisture is above the established threshold, the irrigation cycle is suspended. When moisture falls below that level, the regular watering cycle is allowed.