Research Highlights

Research Highlights
Variable Rate Irrigation Project Springs from KSPB-funded Research

Photo: United Soybean Board

 Kentucky Soybean

It has been said that research often leaves more questions than answers. While that’s not necessarily the case on Trevor Gilkey’s Caldwell County farm, Dr. Ole Wendroth’s research does generate “what ifs” from project to project, with the results building upon themselves. 

In a three-year study (2015-2017) funded by the Kentucky Soybean Board, the Kentucky Corn Growers Association and the Kentucky Small Grain Growers Association, as well as in a Southern Soybean Research Program-funded project including researchers from four states, Dr. Wendroth’s team collected, analyzed and interpreted data obtained from grid sampling taken at Gilkey’s Hillview Farm. The 138-acre field was under pivot irrigation, and the grid sampling measured not only the clay content but also the electrical conductivity of soil. 

The findings of this project indicated that precise soil monitoring was needed in order for the farmers to have improved decision support on when to utilize the irrigation system and how much water to apply. During the third year of this study, a complex monitoring system was installed to monitor soil water changes and water storage. When combined with Landsat data, the researchers sought to better understand the spatial water dynamics and crop yields that differed across the field depending on whether the soil was more or less clayey. 

Photo: Trevor Gilkey

Gilkey said that Dr. Wendroth’s research has helped him to optimize inputs by putting water not only where it’s needed, but also WHEN it’s needed. Fast forward to 2020, when a highly skilled crew from MidValley Irrigation arrived to add controllable nozzles to Gilkey’s pivot. Much like the precision planting technology that farmers use to plant for best results, precision irrigation with nozzle shut-offs placed every 18-feet down the pivot line will allow Gilkey to irrigate the soil with higher clay content differently than he does the portion of the field that is more silty. As we know, clay is more soggy than silty soil. On the other hand, clayey soil dries out much more quickly than a silty soil, which means the clayey soil may need to be irrigated sooner than the silty soil. 

Gilkey uses his pivot not only for irrigation, but also for fertigation (delivery of nutrients by way of a solution run through the pivot), and the installation of controllable nozzles could be a game-changer on input application as well. 

Bill Nace of Mid-Valley Irrigation said that to the best of his knowledge this is the first variable rate irrigation system installed in the state of Kentucky, and he was interested to learn what benefits that Gilkey and Wendroth see. 

Gilkey said, “I have been working with the University (of Kentucky) since 2007. I started out working with Dr. Lloyd Murdock, and now Dr. Wendroth has been doing these irrigation projects out here. I think it’s important for farmers to cooperate with the University folks and let them perform experiments out on the farm. They can do things in the lab and even plot-scale research, but there’s nothing like seeing what happens in an actual working field.”

Gilkey said that he is very interested in water management, and while he knows that the different soil types need different amounts of water, the only way he had available to change the amount of water he was applying was to slow or speed up the pivot. The new system has individual sprinkler controls, which gives him much more flexibility in how much water is applied to what part of the field. 

“I am anxious to see how this works out,” he said. “It’s going to save water and in turn save money, and that will help my operation to be more efficient with our resources.” 

We are also eagerly awaiting the results. 

Published: Feb 15, 2021