Water-saving irrigation can be achieved by using smart irrigation technology. Intelligent irrigation controllers and sensors have been developed to irrigate plants according to their water needs, reducing irrigation water use compared to traditional automated system timers, which irrigate according to a fixed schedule determined by the user. The technology exists as a complete controller or sensor that can be added to existing irrigation timers to create an intelligent controller. Smart irrigation technology uses weather data or soil moisture data to determine the irrigation needs of a landscape.

These products maximize irrigation efficiency by reducing water waste, while maintaining plant health and quality. Incorporating smart irrigation technology in the landscape can potentially reduce outdoor water consumption. This technology is appropriate for small, residential landscapes as well as large, managed landscapes. The following sections describe how each product functions and the advantages and disadvantages of each product. Irrigation managers and homeowners should be aware that smart irrigation technology will need to be periodically adjusted and maintained for maximum water savings.

Soil Moisture Sensor Controllers

The type of smart irrigation controllers includes soil moisture sensor controllers. Instead of using weather data, soil moisture sensor controllers utilize a soil moisture sensor placed belowground in the root zone of lawns to determine water need. The soil moisture sensor estimates the soil volumetric water content. Volumetric water content represents the portion of the total volume of soil occupied by water. The controllers can be adjusted to open the valves and start irrigation once the volumetric water content reaches a user-defined threshold. The appropriate threshold value depends on soil and vegetation type and usually ranges from about 10 percent to 40 percent. Soil moisture sensors must be installed in a representative area of the turf; far enough from sprinkler heads, tree roots, sidewalks and walls.

Similar to ET controllers, soil moisture controllers have been shown to reduce irrigation, while maintaining turfgrass quality. Compared to homeowner irrigation schedules, soil moisture controllers had an average 72 percent irrigation savings and a 34 percent water savings during drought conditions. In some cases, studies have shown smart controllers will increase water use at sites that typically use less than the theoretical irrigation requirement. Typically, soil moisture sensor controllers range from $280 to $1,800. Difference in pricing depends on product manufacturer and end user, either residential or commercial customers.

Smart Irrigation Technology: Add-on Sensors

In many cases, a scheduling irrigation controller is already in use on a property and upgrading to a smart controller is impractical. To increase efficiency of automatic irrigation systems a soil moisture, rain, wind or freeze sensor can be added to upgrade the existing system. Some manufacturers produce devices capable of measuring multiple environmental elements using one apparatus. Many sensors are compatible with existing systems, easy to install and produce similar results to smart irrigation controllers. The add-on sensors are generally more affordable than smart irrigation controllers, assuming a compatible irrigation timer is already installed on site.