Everyone assumed the spreader pattern was 35 feet. Fields at the Southeastern Purdue Agricultural Center were spread with chicken manure based on visual observations that the spreader would cover a 35-foot swath. As it turns out, what everyone assumed about the spread pattern wasn’t true after all.

“It only gets the full spread pattern out about 30 feet, but we probably wouldn’t have picked that up if we hadn’t flown the field with a UAV and picked up an obvious pattern across the field,” says Alex Helms, who works with technology at SEPAC.

The pattern was 30 feet of greener, healthier cover crop followed by 5 feet of lighter-colored cover crop, followed by another 30 feet of greener crop. “We really confirmed one thing and learned another,” Helms says. “Chicken manure obviously made the crop greener and provided more vegetation. We will have to determine if that translated into yield.

“What we learned was that the effective spread pattern of our spreader is only 30 feet, not 35. We’ve been driving too wide and leaving a small strip where enough chicken litter wasn’t applied,” he says.

A lot has been said about whether money invested in unmanned aerial vehicles and associated expenses results in payback. “In this case, we won’t see payback this year, but it could result in a healthy payback starting in 2018,” Helms says. “We will adjust for the spreader not throwing completely as far as we thought, and drive so we have 30-foot swaths instead of 35-foot swaths. If what we apply makes a yield difference, then the payback for figuring this out should add up rather quickly.”

Looking at a UAV image was the only way to solve this riddle, Helms believes. “Because of the width of the combine head, it likely wouldn’t show up on a yield map,” he concludes.