It’s decision-making time again for farmers, and the recent wet weather only complicates these issues. Should I delay planting corn? If I do, how will that decision affect the yield later? Should I consider switching from corn to soybeans?

A new spreadsheet, Planting Decision Model, has been developed on the University of Illinois farmdoc website to provide some answers for farmers, according to Agricultural Economist and Farm Management Specialist Gary Schnitkey.

“The spreadsheet compares corn and soybean returns by planting date,” Schnitkey says. “We’ve built in agronomic functions developed in the U of I Department of Crop Sciences that give an average or a projected yield for different planting dates.  We combine that with the price of corn and soybeans and determine which crop has a higher return on any given planting date.”

Visitors to the U of I farmdoc website can download the spreadsheet. Key factors impacting returns estimates are yield by planting date, harvest-time prices, and non-land costs.

“We’re going to add a couple of other modules as we go through the season. One module will deal with late planting and crop insurance, but right now the returns by planting date are available,” Schnitkey says.

Can farmers switch crops and make money? Schnitkey says probably not.

“Right now those yield functions and very high corn and soybean prices suggest that we wouldn’t want to switch in northern and central Illinois until at least the end of May and early June. In southern Illinois, those decisions to switch from corn to soybeans occur in the last week of May, using yield functions that are defaulted within the model,” he says.

Schnitkey recommends farmers utilize the Returns Estimated by Planting Date sheet in the Planting Decision Model to evaluate whether to switch from corn to soybeans. Switching dates are sensitive to corn and soybean prices.

“Using current commodity prices and costs, switching to more soybeans seems several weeks away,” Schnitkey says. “For northern and central Illinois, corn is projected to be more profitable than soybeans throughout May.  In southern Illinois, corn is projected to be more profitable than soybeans through the last part of May.  Commodity prices play a key role in return differentials.  Current commodity prices favor corn compared to what one would expect with more typical prices.”