The new research updates for yield response to corn plant populations and nitrogen management guidelines for Indiana growers have been posted. The combined cost of seed and nitrogen fertilizer account for nearly half of the total variable cost of Indiana corn production, according to one of the researchers, Bob Nielsen, extension corn specialist at Purdue.
“So these are really important,” he said. “Folks need to make sure they’re using not simply the optimum rates for these two inputs, but also the rates that maximize profitability.”
Nielsen says the research for seeding rates has expanded to 45 large field-scale trials across the state. What they have found is a fairly common optimum seeding rate applicable to most situations in Indiana.
“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. And again it’s a fairly wide range of growing conditions and yield levels as low as roughly 120 bushels to as high as 240-250 bushels, so it’s pretty all-purpose.”
But uniformity across the state is not the rule for nitrogen rates.
“There seem to be more regional differences showing up, and they appear to be related to soil types or soil associations relative to their drainage characteristics, and this ties into the fact that poorly drained soils have a higher 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.”
Nielsen adds, “On the more poorly drained soils of the state, which tend to be northeast, east-central, and central areas of the state, those optimal nitrogen fertilizer rates are in the neighborhood of 215-220 pounds of actual nitrogen per acre.”
Much of the remaining parts of the state have an optimum ranging from 185-195 pounds of nitrogen per acre.
The research is updated annually once harvest is complete and data is analyzed. The updated information is available through the Purdue agronomy department’s Chat ‘n Chew Café website.