Irrigation Scheduling to Optimize Tree Performance

Tacy Callies Irrigation, Tip of the Week

By Davie Kadyampakeni

irrigation scheduling

Proper irrigation scheduling applies an appropriate volume of water to a citrus grove at the appropriate time based on tree need, soil properties and weather conditions. Applying water in the right amount, right quantity and at the right time is very important for getting the best out of citrus trees. Several tools are available for determining when to irrigate, how much to irrigate and where to irrigate. These tools include soil moisture sensors, weather stations and microirrigation controllers, among others.

Use of soil moisture sensors that measure the amount of water in the soil and amount of salts in the soil can help a grower or irrigation manager make sure to water the trees at just the right level without pushing salts beyond the root zone. The goal is to irrigate the trees so that they are not “thirsty” when they need water to manufacture food in the leaves and start forming fruit that will eventually produce juice. Irrigating with the right amount of water is critical, especially on Florida sandy soils where fertilizer leaching is always a problem.

Use of the Florida Automated Weather Network, or other weather stations commercially available and installed in groves, can help a grove manager make the right call on how much water to apply or to shut off irrigation on days when the grove receives ample rainfall. Having a weather station in a grove can also serve a grower well during cold months to be able to turn on irrigation for the right duration to protect citrus trees from freeze damage.

Finally, for growers interested in synchronizing water and liquid fertilizer injections, having a robust microirrigation controller is always important for effective and optimal delivery of water and nutrients in the root zone. Microirrigation controllers are known to increase water-use efficiency due to improved water availability in the root zone.

In conclusion, citrus production managers should accurately determine when and for how long to irrigate. With proper irrigation scheduling, yield will not be limited by water stress. Any degree of water stress or imbalance can produce a deleterious change in physiological activity of growth and production of citrus trees. The number of fruit, fruit size and tree canopy are reduced, and premature fruit drop is increased with water stress. Extension growth in shoots and roots and leaf expansion are all negatively impacted by water stress.

Other benefits of proper irrigation scheduling include reduced loss of nutrients from leaching as a result of excess water applications and reduced pollu­tion of groundwater or surface water from the leaching of nutrients and other chemicals.

Davie Kadyampakeni is an assistant professor at the University of Florida Institute of Food and Agricultural Sciences Citrus Research and Education Center in Lake Alfred.