This year, June-planted crops seem unavoidable. We’ve learned that early planted soybeans offer numerous benefits that ultimately lead to increased yield potential — an earlier canopy shades out weeds, increases light interception and conserves soil moisture. Plus, more vegetative growth/nodes on the main stem support more pods. With wet spring conditions, we know we likely won’t have these opportunities, but we can tweak management now to preserve yield potential.
First, let’s get realistic about yield expectations. According to Michigan State University, you can expect to lose 0.3 to 0.6 bu./A each day planting is delayed after the first week of May, with losses reaching 1 bu./A every day by July 1. This yield loss is a result of fewer nodes developed prior to flowering and slower canopy closure. The good news: August rains can do a lot for a soybean crop, and we’ve seen the positive effect a timely rain can have during seed fill by increasing seed size. Therefore, favorable conditions late in the season may allow us to still achieve respectable yield.
One thing we talk a lot about is canopy closure. Reducing row width (if possible) and increasing planting population (within reason) can allow for faster canopy closure to help us with weeds and light interception. Most land-grant universities agree that populations should be boosted by 10% to 20% in the first three weeks of June. For example, if you generally plant at 140K, consider bumping your population to 155K. Boosting population also provides the benefit of increasing plant height and, therefore, pod height. This is an important consideration since soybeans are photoperiod sensitive — the reason they begin flowering around summer solstice, June 21.
Although specific dates vary across regions, the consensus is to continue to plant full-season varieties until June 15. It may then be appropriate to swap for a half maturity group earlier for the remainder of the month if prevented planting provisions do not pencil out.
For more information, check out the following articles: https://www.canr.msu.edu/news/late_planted_soybean_recommendations