By Stacia Conger

LSU AgCenter Irrigation Specialist

Every July, Smart Irrigation Month celebrates the benefits of efficient irrigation products, highlighting their positive economic and environmental impacts. One major component of gardening is providing sufficient water for plants. Irrigation systems offer home gardeners and landscapers the benefit of consistent and efficient water delivery, ensuring healthier plants while conserving water without all the extra work.

Applying irrigation based on plant water needs is important to maintaining a healthy and vibrant landscape in Louisiana’s hot, humid climate. With average annual rainfall totaling more than 53 inches statewide, irrigation schedules must be dynamic and ever-changing throughout the year. Efficient irrigation must be responsive to the water needs of each unique landscape. Irrigating too much or too often can result in leached nutrients, erosion, runoff, diseases and, ultimately, wasted money.

Smart technologies entered the market in the early 2000s; since then, these technologies have revolutionized irrigation scheduling across many water-restrictive states. These devices were designed to schedule irrigation automatically based on changing plant water needs. Current smart technologies include weather-based irrigation controller (WBIC) and soil moisture sensor (SMS) systems.

WBICs rely on estimates of evapotranspiration (ET) and rainfall. They range significantly in complexity and function across product lines. Typically, ET is used to represent the amount of water that must be replaced by irrigation when rainfall is not sufficient. In most cases, the WBIC replaces the current irrigation timer. Most require user-programmed site conditions so the technology can accurately schedule irrigation based on maintaining well-watered conditions. The most recent WBICs connect to home Wi-Fi so they may access weather forecasts in addition to ET and rainfall data from the general area.

While WBICs use weather data, SMSs use a sensor buried in the root zone to estimate the amount of moisture available to the plant. Residential or light commercial SMSs also have a sensor controller that wires into the existing timer and decides if irrigation is necessary based on a wet-dry threshold. Larger applications typically include the sensor controller functionality within the irrigation controller itself. Sensors act as shutoff devices, resulting in no irrigation if the soil is too wet. If the soil moisture reads less than the threshold, then irrigation occurs based on the programmed schedule. It’s advisable to break up one longer irrigation into multiple shorter irrigations to allow time for infiltration and provide the opportunity for the sensor to bypass some of them when only a portion is needed.

Choosing between WBICs and SMSs can be a consumer preference. SMSs are generally small, cost-effective solutions, but the need for burying additional wires within the landscape may restrict installation options or limit design changes to established landscapes. Costs increase with increasing sophistication (for example, wireless sensors). WBICs may be preferable when direct measurements from the landscape are not necessary.

Research by the University of Florida — also located in a rain-dominated, hot, humid climate — showed that SMSs produced water savings as high as 92% during wet seasons and 55% during dry seasons. The WBICs averaged annual water savings of 43% in a portion of the state with year-round irrigation needs. These savings were achieved by comparing to the monthly irrigation schedule suggested by UF Institute of Food and Agricultural Sciences Extension for the locations of the studies.

It is important for smart technologies to be installed and programmed by someone who is knowledgeable about plant water needs as well as the features of the technology. You can find a list of licensed and insured landscape irrigation contractors on the Louisiana Department of Agriculture and Forestry’s website. These contractors participate in continuing education on a regular basis, and many have the knowledge and resources to help with upgrading your system. Consider reaching out now to find out more about being smart during Smart Irrigation Month.

Irrigation can be controlled by smart technologies, which include weather-based irrigation controller (WBIC) and soil moisture sensor (SMS) systems. Photo by Heather Kirk-Ballard/LSU AgCenter