Here’s Help With Your Toughest Nitrogen Decisions

By: Gene Johnston

How much nitrogen does your corn crop need each year? That question is one of your toughest, you’ve said in surveys.

Newell Kitchen, a soil scientist with the USDA-Agricultural Research Service in Missouri, is sympathetic to your quandary. The sources of plant-available nitrogen in the soil, coupled with the year-to-year variability of weather, make best nitrogen rates in any given year a very inexact science.

“In the past, the answer for many was to err on the high side,” says Kitchen. He worries that too much of that thinking still lingers. Studies indicate that up to 40% of all corn acres get 30 pounds or more of nitrogen they don’t need. The costs, both economically and environmentally, are too big to ignore, Kitchen says.

For one, he points out, numerous university research trials show the need for fertilizer nitrogen is not very related to corn yield. “Sometimes, when the right combination of weather and soil conditions comes together, you get 230-bushel yields on just 30 pounds of applied nitrogen,” he says.