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
“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
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
The first update, “Yield Response to Plant Population for
Corn in Indiana” —
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 versus 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 “Nitrogen Management Guidelines for
Corn in Indiana” — www.agry.purdue.edu/ext/corn/news/timeless/NitrogenMgmt.html.
Nielsen, Camberato and nutrient management planning specialist Brad Joern are
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.”