April Planting Dates Work for Soybeans in Illinois

April Planting Dates Work for Soybeans in Illinois
Emerson Nafziger, Extension Agronomist - University of Illinois

Farmers are pretty used to not thinking about planting soybeans anywhere in the state of Illinois until May. Todd Gleason reports University of Illinois studies beg to differ.

First things first, the south third of Illinois is…
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First things first, the south third of Illinois is just different than the rest of the state. It’s clear, by the University of Illinois planting date studies, that soybeans sown in April can do well there, it’s just really hard to get a good stand. Yields in the top two-thirds of the state respond the same way to earlier planting dates. The earliest dates, starting around the 10th of April, have the highest yields and things fall off as time paces. University of Illinois Extension Agronomist Emerson Nafziger is a bit cautious about this so, he simply states he’d start when field conditions are good to go.

Nafziger :10 …to the first two weeks of May.

Quote Summary - Our work is showing the best time to plant soybeans is the last week of April to the first two weeks of May.

The average maximum yield for soybeans over the 23 site years of the study, gathered from 2010–2015, is 67 bushels to the acre. There is a two-and-a-half bushel decline from April 10 to April 30th, four bushels by May 10th, seven bushels for a delay to May 20th, 11 bushels to the end of the month, 14 by the 10th of June and 19 by the 20th.

Interestingly, comments Nafziger, the usual halfway point for soybean planting in Illinois is about May 20th. That is, he says, only because of the wet conditions that keep farmers out of the field. Given all of this the U of I agronomist says he wouldn’t wait after planting corn to start planting soybeans.

Nafziger :50 …keep them physiologically below there maximum yield.

Quote Summary - Sure, no problem with that at all. We’ve seen some sizable yield losses with soybeans by planting too early, but by too early I mean the first half of April. The two ways you can get lower yields from planting too early in soybeans are years like 2012, when planting late you picked up moisture later in the season to get better yields. In-other-words, too much dry weather during flowering can really do a number of the crop. The other is if it gets really cool early after soybeans have emerged. It can actually keep them physiologically below their maximum yield.

Pragmatically speaking Emerson Nafziger says, as long as soil conditions are good, he’d begin planting soybeans as soon as corn planting is completed and, after some momentary consideration, says he’d move to a soybean field if soil conditions in the next corn field weren’t up to par.