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Published May 12, 2014, 09:28 AM

Corn 'N' calculator released

Dave Franzen, a North Dakota State University Extension Service soil scientist, in late April completed a major recalculation of nitrogen recommendations for corn and posted it on his website.

By: Mikkel Pates, Agweek

FARGO, N.D. — Dave Franzen, a North Dakota State University Extension Service soil scientist, in late April completed a major recalculation of nitrogen recommendations for corn and posted it on his website: www.ndsu.edu/pubweb/soils/corn.

The North Dakota Corn Council paid for research to update nitrogen recommendations that had been on the books for a number of years in North Dakota, says Tom Lilja, executive director for the council.

“He did a good job of breaking out different soil classifications, different climate zones,” Lilja says of Franzen.

The old, outdated recommendations were more “across-the-board,” and based solely on yield, minus the credits from a carryover.

“That never really worked,” Franzen says. Generally, the new formula could adjust recommendations downward for the region’s irrigators. Others could use more or the same, but will be side-dressing in light-textured soils or high-clay soils.

The new pre-plant recommendations are based on choices, starting with whether you farm west of the Missouri River, or to the east.

For east come three choices: no-till for more than six years; irrigated corn; or conventional till and no till. There are choices for high- and low-clay soils, and historic yields of less than 160 bushels per acre or high yields at 160 or more.

To come up with a pounds-per-acre recommendation, the farmer plugs in the expected price of corn and the nearest nitrogen costs, and the soil test analysis in pounds per acre to a 2-foot depth. The recommendation adjusts downward with organic matter above 6 percent. It also includes a choice for the previous crop — either a crop that doesn’t supply nitrogen or one that does — soybeans, sugar beets, harvested alfalfa or unharvest- ed sweet clover, with various nuances.

The calculator is based on five years of research and 115 site years of data including input from the North Dakota Corn Council, the International Plant Nutrition Institute, Pioneer Hi-Bred, the University of Minnesota, Manitoba Agriculture and South Dakota State University.

If the soil is less productive, Franzen recommends using a lower rate than the formula recommends and he “strongly, strongly” recommends side-dressing. In high-clay or low-productivity fields, he suggests cutting the pre-plant recom- mendation in half and coming back with side-dressing when the corn is at the “V-6” or “V-8” rates, referring to the standard vegetative index. He says computer science colleagues are also working on ways farmers can input their own data to allow the formula to fit their situation.

Franzen says the system is based on an “economic production function,” developed first in Iowa and Illinois and expanded to other corn states. Most states don’t offer a choice based on soil types, as North Dakota does. The formula is based on the “law of diminishing returns” — an economic principle that says the first increment of input gives the most response.

“The whole purpose of the recommendation is to maximize profit,” Franzen says. “The plus or minus … Farmers will customize the formula based on their history or personal goals.”

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