In recent years our idea of “optimal” soybean planting dates in Illinois has shifted earlier. Researchers and farmers pushing the envelope looking for higher soybean yields have observed early planted soybeans have more yield potential. Greater yield potential comes as a result of more main stem nodes and a more fully developed canopy capable of capturing more sunlight in June and early July. So, you may be asking… What is early? How early is too early? What are the risks vs. rewards of early planting? Can I afford to be equipped to plant corn and soybeans at the same time? If I am planting earlier, should I be planting fuller season varieties?
As with most topics in agronomy you will get different opinions to these questions based on who you ask. In most situations I would define “early” as anything planted before May 5th and “too early” as anything planted before April 15th. In our planting date studies the highest yields typically come from planting dates between April 20th and May 5th. You may be thinking… “hey, that’s a pretty good time to plant corn too” and you would be correct.
Unless you get a very early start to corn planting and it goes very quickly it may be hard to hit this early soybean planting window consistently unless you have the manpower and equipment to plant both crops at the same time. Depending on the number of acres you farm and the availability of labor and capital it may or may not make sense to be capable of planting corn and soybeans at the same time. Agronomically it makes a lot of sense but financially it may not, and especially now with low commodity prices.
Earlier planting often means you are planting into cooler soils and your potential for some diseases and stand establishment issues increase. These risks can be reduced by the use of seed treatments, variety selection and good ol’ common sense. Only plant early when you have good soil conditions. Soil temperatures above 55°F and a favorable weather forecast for the next 5-7 days after planting help as well.
Good soil conditions at planting are important. It can be hard to pass up perfect soil conditions that present themselves when you know it is still too early to plant. In many parts of Illinois this year soil conditions were better in mid-March than they often are in April and May. Passing up these ultra-early windows when they present themselves is hard but very frequently the right thing to do.
When you decided what soybeans you were going to plant this year you probably had a planting date target in mind but you really had no idea when you would be able to plant. Planting early can enable you to plant later relative maturities that tend to have more yield potential. This can be hard to manage given when we order seed and apply seed treatments. Generally speaking, you should be able to plant fuller season soybeans without significant harvest delays if you plant early.
In summary my standard recommendation is to plant a range of maturities skewed towards fuller season. Plant your earliest maturity products first as early as soil, weather, equipment and labor limitations will allow.
Lance Tarochione is a technical agronomist with Asgrow/DEKALB in west central Illinois. His work has focused on crop production, research and product development, and through his role at Monsanto® he currently supports the Asgrow® and DEKALB® brands in seven counties in western Illinois.