Variable-rate nitrogen prescriptions By: , In: Article

Despite his work to build a successful variable-rate nitrogen program on his farm over the past five years, Corey Holmes was in for some surprises in 2015 from a new online nitrogen tool that sometimes seemed to know his farms better than he did.

Holmes has prescription-applied nitrogen based on soil organic matter and soil types since 2010. That practice followed a wet 2009 that convinced him he had to make some changes.

“Weather patterns keep getting wilder,” says Holmes, who farms with his father, Rick, near Lincoln, Ill. “We knew we had to do something.”

No more fall nitrogen

He eliminated fall nitrogen applications. Instead, he shifted to a spring preplant urea program, followed by hand-calculated variable-rate sidedress applications of anhydrous ammonia on the operations’ mostly continuous corn operation.

A “binge of studies” over two years showed an average yield increase from variable-rate nitrogen applications of 15 bushels/acre, even as total nitrogen use dropped 10 percent. As he continued to refine his system, Holmes was curious about what new tools could teach him – and whether it would add more bushels to the bin.

He learned plenty from a new variable-rate nitrogen tool from FarmLogs that he and other farmers tested 2015. It added an estimated 5-10 bushels/acre to yields on test fields compared to his standard variable-rate nitrogen program.

“We think we know our farms, so it is tough to believe in a computer telling you what is going to happen on the ground, especially when it’s different than what you think,” he says.

“I was surprised at times,” he says.

Trust computer model?