Purdue researchers have published a new report with updated guidelines to help farmers use nitrogen more cost effectively.

The amount of nitrogen needed in a particular field varies by region and is determined by the characteristics of the soil, said Jim Camberato, co-author of the report, "Nutrient Management Guidelines for Corn in Indiana."

"At some level, grain yield stops increasing with more nitrogen," Camberato said. "Consequently, applying more nitrogen than the crop requires is dollar wasteful and could be environmentally unsound."

Nitrogen is one of the most expensive nutrients in corn production. If properly applied, nitrogen can help increase yield. But applying too much is costly, Camberato said.

"Unfortunately, the corn plant is unable to use all of the applied nitrogen and some of it inevitably leaves the field, polluting the water and air," Camberato said.

Generally, soil with a higher concentration of organic matter and better drainage requires less nitrogen, Camberato said.

The report, available at http://www.kingcorn.org/news/timeless/NitrogenMgmt.pdf, includes tables listing recommended rates of application for all regions in Indiana.

"The guidelines are about 30-40 pounds per acre less in west-central and southwest Indiana than in the central, east-central and northeast regions of the state," Camberato said. "Other areas fall in between. The recommended rates are for corn in rotation with soybeans and are based on corn and nitrogen prices, which can vary."

The study was based on data collected from field studies throughout the state beginning in 2006. Camberato said he and co-author Bob Nielsen, Extension corn specialist, hope to regularly update and improve the soil-specific guidelines based on additional research.

They are recruiting farmers who would like to participate in the next round of studies. For more information, contact Camberato at jcambera@purdue.edu or 765-496-9338, or Nielsen at rnielsen@purdue.edu or 765-494-4802. Anyone interested in participating in the studies can also contact their local Extension educator.