While standard advice about fall fertilizer applications hasn’t changed too much, technology has improved the efficiency with which farmers can control inputs. That results in better risk management.
"As we’ve gotten into the world of precision, we can do a lot better job," says George Rehm, soil scientist, University of Minnesota Extension.
For nitrogen, that means planning a split application. Historically, fall nitrogen application has been confined to the western half of the Corn Belt. With advances in precision application, it’s possible to pare back nitrogen use even further to cut input losses.
"We reduce the risk by using the soil sample procedure, and then with variable rate and precision sampling, and grid sampling, and sampling by zones … this becomes more important," Rehm says.
It’s also a good idea to use nitrogen stabilizers, Rehm says, the most reliable being N-Serve and Instinct. Carefully verify the claims of any additives on the market with a fertilizer dealer, crop consultant or land-grant university expert before making a purchase, he adds.
With phosphorus and potassium, use a banded application in conjunction with GPS.
"From a risk-management standpoint, that’s the least risky when it comes to P and K," Rehm says. "I know where I’m going to put the row, I know where that band of fertilizer is, and when I band, I reduce the contact between fertilizer and soil. If I reduce the contact between fertilizer and soil, I increase the nutrient use efficiency for P and K."
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