COLUMBIA, Mo.– The Useful to Usable (U2U) climate initiative recently launched a new online decision-making tool, Corn Split N, that helps farmers and crop advisers manage the application of in-field nitrogen for maximum crop yields and minimum environmental damage.

The free tool, available for use in Illinois, Iowa, Indiana, Missouri and Kansas, combines historical weather data and fieldwork conditions with economic considerations to determine the feasibility and profitability of post-planting nitrogen application. The product will be available in seven additional north-central states in 2015: Wisconsin, Minnesota, South Dakota, North Dakota, Nebraska, Ohio and Michigan.

Ray Massey, University of Missouri Extension economist and Corn Split N project developer, says, “Traditionally, farmers have applied nitrogen to the soil in a single pass, either in the fall or in the spring before planting.” However, he says, farmers might instead want to split the nitrogen over two intervals—once in the fall or spring when the soil is not saturated and the temperature is 32-50 degrees Fahrenheit, and a second time when plants are in the ground and most in need of nitrogen. “Research has shown that will ultimately lead to better results because less fertilizer will be needed overall and not as much will be lost in runoff.”

Proper timing of nitrogen application varies depending on the weather and soil conditions, Massey says. Corn Split N’s historical climate data helps farmers pinpoint when to apply nitrogen for best results.

Because the post-planting application must be done before the corn gets too tall, the tool also takes into account estimates of corn development states based on location, selected planting date and accumulated corn growing degree days (GDD) for the year. GDD accumulations and associated corn growth beyond the current day are estimated based on the historical 30-year (1981-2010) average GDD accumulation for a location.

Massey noted that the Corn Split N tool helps farmers quantify the costs and benefits under an average, worst-case and best-case scenario when doing a post-planting nitrogen application, even taking into account two passes of ground equipment in the fields.

Farmers get customized results based on their planting and fertilization schedule, local costs and available equipment. A summarized fieldwork table and crop calendar makes it easy for farmers to see how schedule adjustments might affect their ability to fertilize on time.

Corn Split N is part of the U2U suite of tools created to help farmers and agricultural advisers manage increasingly variable weather and climate conditions across the Corn Belt. For more information, go to

Useful to Usable is a USDA-funded research and extension project comprising 50 faculty, staff and students from nine north-central U.S. universities with expertise in applied climatology, crop modeling, agronomy, cybertechnology, and agricultural economics and other social sciences.

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