Soil Moisture Sensors Can Help Boost Florida Blueberry Production

by Diego Cabezas

In Florida production systems, blueberries are commonly established in sandy soils amended with milled pine bark or in beds solely made up of pine bark. These substrates are characterized by shallow effective rooting depth and low water-holding capacity, making plants highly susceptible to rapid fluctuations in soil moisture and drought stress. The adoption of soil moisture sensors offers growers a quantitative framework for optimizing irrigation scheduling. When sensor data are integrated with localized weather information and systematic field monitoring, irrigation decisions can be fine-tuned to improve both water- and nutrient-use efficiency. Precision irrigation reduces leaching losses, enhances nutrient uptake, and has the potential to lower production costs while increasing economic returns.

Why Soil Moisture Sensors Matter

• Florida blueberries are commonly grown in sandy soils, amended with pine bark, which drain rapidly and dry out quickly. Precise irrigation timing is essential: overwatering in poor drained soils could lead to Phytophthora root rot problems, reduce yields, and increase production costs, while also causing fertilizer leaching that limits nutrient uptake. Equally, underwatering stresses plants and reduces growth and fruit quality, highlighting the need for careful water management.

• Highbush blueberries have shallow root systems, with the majority of roots concentrated in the top 12 inches of amended soil. Soil moisture sensors enable growers to monitor conditions at multiple depths, aligning irrigation with actual plant water uptake. This improves efficiency in the use of resources such as water, fertilizer, electricity/diesel cost.

Choosing the Right Sensor

• Soil moisture sensors are generally categorized as volumetric (measuring water content) or tensiometric (measuring soil suction). In Florida’s sandy, bark-amended soils, volumetric sensors are more reliable. Tensiometers often lose suction in these conditions, leading to inaccurate readings and potentially poor irrigation decisions. Sensor reading should always be interpreted alongside direct field observations.

• Among volumetric options, time domain reflectometry (TDR) and time domain transmission (TDT) sensors are recommended for their accuracy, low maintenance, and minimal calibration requirements.

Best Practices for Moisture Sensor Installation and Use

1. Position sensors in the active root zone (6″–12″ deep). Additional sensors at 18–20″ can help evaluate leaching below the root zone.

2. Select representative locations in the field, avoiding edges or atypical sites, which could lead to misreadings. 

3. For solar- or battery-powered units, ensure adequate light exposure and protect cables from physical damage.

4. Use field calibration—such as saturated soil baselines and gravimetric sampling—to improve accuracy under variable sandy soil conditions.

5. Interpret long-term data trends rather than isolated readings to avoid over- or under-irrigation.

Pulse Irrigation: Insights for Florida Growers

Research by Dr. David Bryla (USDA-ARS, Corvallis, OR) in eastern Washington has shown that pulse irrigation—applying smaller volumes of water multiple times per day instead of a single large irrigation—can improve blueberry water status, root activity, and nutrient uptake.

While Florida soils and climate differ from eastern Washington, the underlying principle applies dividing irrigation into smaller, frequent applications can help maintain more stable soil moisture in shallow root zones, especially in sandy, pine-bark–amended soils common in Florida.

Potential benefits for Florida growers include:

• Reduced midday plant stress and more consistent soil moisture.

• Improved root health and activity by avoiding cycles of saturation and drying.

• Enhanced fertilizer use efficiency by minimizing leaching below the root zone.

When combined with soil moisture sensors, pulse irrigation may help growers apply water only when and where it’s needed, improving both resource efficiency and plant performance. Research to confirm its effectiveness in Florida blueberry fields needs to be conducted.

Benefits of Moisture Sensor for Florida Blueberry Growers

• Optimized irrigation scheduling maintains soil moisture within a target range, replenishing only what is lost to evapotranspiration.

• Reduced water use and improved plant performance by avoiding both drought stress and excess moisture.

• Greater understanding of root-zone dynamics, allowing for more effective responses during periods of peak water demand.

Citations

• Dourte, D. R., Migliaccio, K. W., & Fraisse, C. W. (2017). Soil Moisture Sensor Use in Irrigation Scheduling. UF/IFAS Extension, EDIS HS1432. https://edis.ifas.ufl.edu/publication/HS1432

• Zotarelli, L., Dukes, M. D., & Morgan, K. T. (2010). Irrigation Scheduling for Agriculture. UF/IFAS Extension, EDIS AE266.

• Florida Blueberry Growers Association. (2019). Summer Irrigation of Florida Blueberries. https://www.floridablueberrygrowers.org

• Obreza, T. A., & Zekri, M. (2022). Soil Moisture Monitoring for Citrus and Other Crops. UF/IFAS Citrus Research and Education Center.

• Fruit Growers News. (2023). Southeast growers turning to soil moisture sensors. https://fruitgrowersnews.com

• Bryla, D. R., & Strik, B. C. (2007). Effects of irrigation method and nitrogen fertigation on growth and yield of highbush blueberry. HortScience, 42(6), 1463–1467.

• Bryla, D. R. (2011). Crop evapotranspiration and irrigation scheduling in northern highbush blueberry. Acta Horticulturae, 922, 301–318.

• Carroll, J. L., Orr, S. T., Retano, A., Gregory, A., Benedict, C. A., Bryla, D. R. (2024). Weather-based Scheduling and Pulse Drip Irrigation Increase Growth and Production of Northern Highbush Blueberry. HortScience, 59(5), 571–577. https://doi.org/10.21273/HORTSCI17527-23