The Dual Systems Approach: Optimizing Blueberry Irrigation

dual systems approach to irrigation

Blueberries are a staple crop of the fruit industry in Oregon, especially in the Willamette Valley. Early in the Willamette Valley’s blueberry boom, most farmers were relying on high-volume impact sprinklers as the primary source of irrigation for their blueberry establishment.

While this method was initially effective, the need for water conservation and the requirement to efficiently irrigate larger blocks eventually revealed its limitations. Willamette Valley farmers began shifting away from high-volume impact sprinklers and began adopting primarily drip irrigation. Drip allowed farmers to cover more acres at once while still effectively and efficiently feeding their crop with water and nutrients.

As farmers shifted from overhead irrigation systems, they began to recognize specific situations where overhead sprinklers still had valuable uses (although acknowledging their inefficiency due to excessive water consumption). Farmers became aware of the value in applying water in the crop canopy to help reduce extreme ambient temperatures. In addition, a challenge emerged as drip irrigation particularly struggled in the late irrigation months to adequately saturate the soil profile. The limited lateral movement of water between the drip emitters in the late-season created challenges for the blueberry plants to uniformly access water.

These current challenges are promoting growers to reevaluate overhead irrigation, switching to a “dual systems approach” with drip irrigation in combination with overhead sprinklers. The integration of drip irrigation reduced their reliance on high water volumes and reduced high pump pressure requirements. Although drip irrigation alone brings immense value, a “dual systems approach” is the blueberry irrigation ideal. 

Here at Stettler Supply, we provide improved sprinkler design and technology. We provide systems that operate with approximately 20% to 25% of the overall flow rate compared to the old, high-impact overhead method. We can offer a much softer delivery of the water with much higher uniformities. This technology allows growers to operate a single overhead sprinkler system to add value in evaporative cooling, frost protection, insecticide chemigation, and supplemental irrigation, hence the dual systems approach.

In all of these layered benefits, we can see a theme of risk mitigation and increased management ability. As our markets and economic landscape evolve, the demand for consistent high yields, crop quality, and farm efficiency has never been higher. As growers, it’s important to invest in systems that allow us to have greater influence and control over both anticipated and unexpected variables that fruit producers encounter each year.

Here is a more detailed look at how these irrigation systems work.

Evaporative Cooling for Blueberries

Evaporative cooling is an effective tool to manage and regulate canopy temperatures, keeping blueberries protected from heat damage. When field temperatures reach near critical temperature for blueberries, cooling sprinklers can be turned on, dispersing small droplets of water into the air. This creates a microclimate through the water evaporation and reduces the ambient temperature, saving the crop from extreme heat damage or even total loss. These cooling irrigation systems can be run on automated irrigation programs and can be monitored and operated through irrigation automation and technology.

Frost Protection for Blueberries

Overhead sprinkler irrigation is a commonly used method for frost protection. This technique involves running overhead micro sprinklers during a frost or critical low-temperature event to wet the blueberry plants. As the water freezes, it releases latent heat which helps stabilize and keep the plant temperatures just above freezing. This can protect new growth and fruit buds from below freezing temperatures and potential crop loss. Frost protection irrigation schedules can also be automated from irrigation automation and maintained temperatures based on temperature sensors.

IPM, Chemigation through Overhead Irrigation

Pest management in blueberries is critical especially when the fruit begins to mature and pests, such as spotted wing drosophila, start to become a threat. As the fruit starts to turn from green to purple, it becomes vulnerable to these pests and chemigation through overhead micro irrigation is a very useful tool.

Because of the uniformity and accuracy of the overhead irrigation, insecticides can be injected at a central location and accurately injected into the system. The low-volume sprinklers provide a great level of canopy coverage and distribute the insecticide blended with water. There is great data with proven efficacy using these systems. Chemigation through overhead micro sprinkler systems has grown in popularity because of this efficacy and the ability to treat large acres with minimal labor costs.

Supplemental Irrigation

In late season irrigation, our soils can start to deplete in subsoil moisture. With drip irrigation, we have a single point irrigation method. While drip irrigation is highly valuable and effective, relying solely on drip irrigation during late-season irrigation can sometimes result in dry areas within the root zone.

Blueberries are shallow rooted plants and draw their moisture close to the soil surface. They also have fibrous roots that thrive in a moist, organic-rich environment. Today, the standard practice is to cultivate blueberries either on raised berms with incorporated sawdust or flat-planted with sawdust tilled into the plant’s root zone. The presence of sawdust can reduce the soil’s moisture retention capacity, posing challenges for drip irrigation once the water demand of the plants starts to increase as the crop develops.

Close emitter spacing helps when combatting this problem, but often overhead irrigation is a great solution for periodically replenishing the active root area and enhancing water availability to the plants. Growers across the Willamette Valley have discovered this added benefit from low-volume overhead irrigation systems and have begun to add this tool for supplemental irrigation needs.

In summary, the “dual systems approach” represents significant advancements in blueberry farming and offers a comprehensive solution. We can address multiple challenges while increasing crop protection, quality, and sustainability. Oregon blueberry growers can benefit from these innovative techniques to maximize their operations and mitigate risks associated with weather, pests and mother nature.

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