Variable Rate Fertigation increases value and efficiency of irrigation

Precision agriculture powered by GPS technology—at first a novelty—has now become the norm, driven in part by economic necessity. Putting fertilizer where it is most needed, in the precise amounts required, improves both input utilization and final yields.

That variable-rate technology, first applied to dry fertilizer application, is now beginning to revolutionize the irrigation industry. A new world where a network of sensors constantly monitors soil moisture conditions and directs systems capable of variable-rate irrigation is rapidly becoming a reality.

This next-generation approach to irrigation is also creating opportunities for more precise and effective application of liquid fertilizer and crop protection products through those systems. Retailers specializing in fluid injection technology, like Agri-Inject of Yuma, Colorado, believe the timing is perfect for this precision revolution.

“Water is an increasingly precious resource,” notes Agri-Inject CEO Erik Tribelhorn. “Couple that with the growing regulatory focus on minimizing nutrient leaching and runoff, and the stage is set for systems that manage both water and nutrients with greater precision.”

Close to home

The engineers at Agri-Inject don’t have to look far to find a real-world scenario in which to develop their variable-rate fluid injection control systems. Farmers in the irrigated western U.S. are increasingly facing regulatory pumping restrictions which limit the amount of water that can be drawn from high-capacity wells each year. Consequently, farmers in their area are very interested in ways to use water more efficiently.

One answer is variable-rate irrigation, which uses sprinklers that can be turned on and off to match the water needs of a growing crop. That also makes the system a perfect vehicle for variable-rate chemigation/fertigation. The challenge—developing a system that can monitor water flow in the irrigation system and adjust fertilizer or chemical rates on the fly.

“That’s exactly what our reflex® proportional injection system was designed to do,” says Tribelhorn. “Irrigation applications now vary based on crop, soil type, moisture probe input, sprinkler speed and other variables. The reflex system senses changing water flows and immediately adjusts injection rates to ensure consistent coverage.”

Putting it together

All the elements—variable-rate irrigation systems, fluid injection controllers and soil moisture sensors—take irrigation, fertigation and chemigation where they have never gone before. What does it look like when all these tools come together? Look no further than the Irrigation Research Foundation farm north of Yuma.

There, researchers bring together all these components and field test systems to gather real-world data. A full-size pivot utilizes variable-rate sprinkler heads, in-ground moisture sensors and an Agri-Inject fluid injection system and reflex control panel that enable system users to receive real-time data and make application adjustments on the fly. In fact, the prescription for a given field can be changed every 15 minutes if necessary.

“By taking advantage of the advancements in equipment and technology, irrigation, chemigation and fertigation have achieved new levels of efficiency and precision,” Tribelhorn says. “The more precise irrigation becomes, the more valuable of a tool an irrigation system becomes—especially when production margins are as tight as they are today.”