Growers’ Perspective on Optimizing Irrigation Methods for Blueberry Crops
Waste not. Want not. It’s a common enough saying, but for Florida’s blueberry farmers, conserving water is a high priority— for reasons including practicing sustainable agriculture for future generations, as well as protecting profits to keep the operation growing. Florida ranks as one of the top 10 blueberry-producing states in the country, but depending on the weather, the earlier-than-average harvest window that Florida lays claim to can be encroached upon by Georgia, California, and Mexico at harvest time. Florida growers need every advantage they can get, and one big advantage is an efficient and optimized irrigation system.
Rabbiteye and southern highbush varieties are the plants of choice for local growers. They thrive on acidic soils with more organic matter than typically found in Florida’s sandy soil. Peat moss or pine bark are the go-to mulches for growers, which increase soil organic matter while helping retain moisture. Of course, it’s a delicate balance. Lack of water can reduce berry yield and quality, while making the plant more at risk for a variety of diseases like blueberry stem blight. On the flip side of that coin, excessive soil moisture will weaken root systems and promote soil-borne diseases. However, Florida’s sandy soil, even when supplemented with organic mulch, is fairly porous and does not retain water like the soil in Georgia, which has a higher clay content. Additionally, southern highbush blueberry varieties have a shallow root system, with most roots just a few inches below the surface, making them susceptible to stress-related symptoms from periodic drought. To combat the native soil’s limitations, seasoned growers have developed a combination of irrigation methods.Ken Patterson is the owner of Island Grove Winery. He has farms near Gainesville and in south Florida. Patterson has been in the business a while and when it comes to irrigation methods, he says, “I’ve seen quite a few changes.”Several factors determine how much irrigation a plant needs, such as the size of the canopy, what stage of growth the plant is at, and the environmental conditions of the area. As with any plant, the larger the blueberry bush, the more water it will require. Florida growers commonly use a combination of drip and overhead irrigation. Overhead is used as freeze protection and is good for young plants establishing their root system. It’s also helpful during drought conditions as a supplemental watering tactic in addition to drip irrigation. Bill Braswell, past president of the Florida Blueberry Growers Association, who grows on his farm in Polk County, suggests an alternative method for freeze control. “I use wind machines for frost and freeze in place of overhead irrigation,” he points out. For normal irrigation, Braswell uses a drip system. Drip systems are a good choice for injecting fertilizers and chemicals into the soil. Drip systems do tend to provide a more vertical dispersion of water, not following the natural horizontal spread of the root system. Dan Kimble, owner of Harplyn Ag, agricultural irrigation specialists, says the solution is simple: “Always do two drip lines,” he suggests to growers, to help increase horizontal coverage of the root system.
One solution is a properly designed micro-sprinkler system. These can provide better lateral coverage for the root system. But so far, this system has not become widely popular in Florida. Thanks to the porous soil and shallow root system, many growers have found that “pulse irrigation” works better for larger plants. This method uses multiple irrigations for a short period of time to help reduce water loss to deep drainage.
A late freeze in March most likely delayed the harvest from Georgia, giving Florida growers a boost with potentially less competition toward the latter part of the spring harvest. “We’ll probably have a good season,” remarks Braswell. As they wrap up this season and look forward to next year, Kimble suggests (if growers haven’t already) that they should automate their systems. “Put in a timer and control your zones with hydraulic valves,” he advises, and make sure to incorporate the best irrigation methods for the crops location and environment. Patterson installed an automated system at his south Florida farm, and is in the process of converting his farm near Gainesville. “It’s the biggest bang for the least amount of water,” he explains. Optimum and efficient use of water with less waste is good for crops and the local ecosystem. As for good weather, we’ll just have to keep our fingers crossed.
By Bonny Johnson