By Sandra M. Guzmán and Amir Rezazadeh
During Florida’s rainy and hurricane season, accurate water management becomes even more critical for citrus growers. Soil moisture sensors (SMSs) can be used as a baseline tool for making informed irrigation decisions. But to get reliable readings, it is critical to choose, install and use them correctly.
WHERE TO INSTALL
Proper SMS placement is essential. Choose a spot representing average soil and irrigation conditions, ideally as close to the tree root zone as possible but outside areas with rocks, or at the beginning/end of the irrigation line. For drip irrigation, install the sensor near the wet area of the dripper. For microsprinkler systems, locate a spot that’s consistently wet but not right next to the microsprinkler.
CALIBRATE FOR LOCAL CONDITIONS
While most SMSs come pre-calibrated, field calibration can improve accuracy, especially in Florida’s variable sandy soils. Installing a sensor when the soil has become saturated following a rain event is beneficial. Tracking the readings over a week after installation will allow the identification of high water-availability thresholds. Soil samples for gravimetric measurement can help verify sensor data as well. Contact University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Extension or your sensor manufacturer for necessary calibration support.
AVOID INSTALLATION PITFALLS
Objects such as rocks, large roots and air gaps inside the sensor’s “sensing volume” can disrupt the sensor’s electrical flow. Always check and prepare the site before installation to ensure enough soil coverage around the sensor. For wired telemetry units, plan cable routes and bury cables to avoid damage from farming equipment or animals.
MAKE THE MOST OF REAL-TIME DATA
Modern SMS systems can transmit data to your phone or computer, making it easy to adjust field management in response to storms or changing weather. Regularly reviewing sensor readings, graphical soil moisture trends and weather data makes it possible to track the water status of the field.
Water movement across the soil can be identified using two or more soil moisture sensors, such as when probes are installed (one at 3 to 7 inches and another at 8 to 16 inches deep). The top sensor in Figure 2 (green gauge and line) tracks moisture where most roots absorb water and is the best indicator for daily irrigation needs. The bottom sensor (yellow gauge and line) monitors deeper soil moisture, helping to see if water, after irrigation or rain, is moving too far down where roots can’t reach it. These lower sensor trends can indicate water table elevation during the rainy season.
Growers may effectively manage water during Florida’s rainy season by using site-specific information from the thoughtful selection and installation of soil moisture sensors. Modern systems can integrate projected water requirements, rainfall and other meteorological data.
For further information or practical help managing sensors and data, contact your local UF/IFAS citrus agent.
Sandra M. Guzmán is an assistant professor at the UF/IFAS Indian River Research and Education Center in Fort Pierce. Amir Rezazadeh is the fruit and alternative crops UF/IFAS Extension agent in St. Lucie County.
Share this Post