Illinois Fertilizer & Chemical Association
Supply · Service · Stewardship

How to find the right N rate

Two years ago, Decatur, Ill., farmer Adam Brown began dropping nitrogen rates, from 230 pounds per acre to 200 pounds.
With yield monitor data from two years of harvest, he says he’s confident the decision to reduce N rates on corn isn’t impacting his yields. In 2020, yields are averaging 226 bushels per acre — 10 bushels above his farm’s three-year average production history from 2016-18.
“I think that’s one place where my operation has thrived,” Brown says. “I’m not necessarily the best at any particular practice, but what I try to do is replicate success that I see in trials.” Brown is referencing the dozens of rate trials that provide data for the tool he uses to calculate rates, the Maximum Return to N calculator from the University of Illinois. Data from across the state extends back more than six years, with older data deleted as newer data comes in. Learn more at
Brown says he’ll likely reduce N rates even more in 2021. He’s got room to move, since his current rates are at the top end of the MRTN-recommended rate.
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