Purdue agronomists offer post-harvest corn research updates

WEST LAFAYETTE, Ind. - Purdue Extension agronomists have published research updates regarding corn plant populations and nitrogen management guidelines for Indiana growers.

Plant populations and nitrogen rates are hot topics in agriculture as input costs continue to be high and growers seek to optimize yields.

"These two variable crop inputs are the most expensive that farmers deal with," said Bob Nielsen, corn specialist. "The better we can understand them, the better we can ensure they are being used as efficiently as possible."

Nielsen and other Purdue agronomists have conducted a series of field-scale corn plant population trials around Indiana since 2001. They also have conducted a series of statewide, field-scale nitrogen management trials for the last eight years.

Their findings are updated annually once harvest is complete and data is analyzed. The updated information is available through the agronomy department's Chat 'n Chew Café website at http://www.agry.purdue.edu/ext/corn/café.

The first update, Yield Response to Plant Population for Corn in Indiana (http://www.agry.purdue.edu/ext/corn/news/timeless/SeedingRateGuidelines.html) was authored by Nielsen and soil fertility specialist Jim Camberato. It includes information about how and why the trials are conducted and results, including those for normal vs. stressed growing conditions, hybrid differences and more.

"There seems to be a fairly common optimum seeding rate that is applicable to most situations in the state," Nielsen said. "Basically, it's a final plant population of roughly 31,000 plants per acre, which would translate to a seeding rate of maybe 32,000 or 33,000 for most people."

The second update is titled Nitrogen Management Guidelines for Corn in Indiana (http://www.agry.purdue.edu/ext/corn/news/timeless/NitrogenMgmt.html). Nielsen, Camberato and nutrient management planning specialist Brad Joern are the authors.

The updated article focuses optimum nitrogen application rates, including regional and soil differences. It includes charts and graphs that help growers make economically sound decisions about application rates depending on grain prices, nitrogen costs and yield response data.

"We've not seen an optimum nitrogen rate that is applicable to such a wide range of conditions in the state," Nielsen said. "There seem to be more regional differences showing up, and they appear to be related to soil types relative to their drainage characteristics.

"Poorly drained soils have a greater risk of nitrogen loss due to denitrification, so sometimes nitrogen fertilizer rates need to be higher on those soils in order to have enough nitrogen left over for the crop."

Source: Purdue University