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Have you ever considered planting soybeans at the same time as corn? What about before corn? Most farmers don’t consider these options because it costs more to plant an acre of corn than it does soybeans, and the risk of lower yield from delayed corn planting is always higher.

Each year, Beck’s PFR Practical Farm Research® (PFR™) team conducts a planting date study of both corn and soybeans to determine the optimal window for planting. The data has consistently shown that the optimum planting date window for soybeans is from late April to early May, as shown below.

Several general trends can be noted from this data. One of the most important trends at most Beck’s PFR sites is that the optimum planting date for soybeans is the same or earlier than that of corn. 

Although Beck’s hasn’t conducted planting date research at a PFR site in northern Illinois, most of the data from adjacent areas suggest an optimum planting date window of April 15 to April 30.

Beck’s five-year, multi-location replicated research shows a $146.49/A advantage from planting soybeans April 16 to May 15 versus May 16 to June 15. Earlier flowering is one reason for the higher yields and increased return with earlier planted soybeans. This allows the plant to accumulate more GDUs between flowering and harvest.

Considering these yield results, a recommended best practice is to plant soybeans immediately after planting corn. Or, if your farming operation allows, plant corn and soybeans at the same time. Data proves that earlier soybean planting will put money in your pocket.

Planting soybeans earlier in the season can result in earlier canopy closure, which leads to cooler soil temperatures throughout the season. For example, in Ohio in July there is a 7- to 14-degree Fahrenheit difference in soil temperature when comparing the earliest and latest planting dates. These temperatures taken within the canopy demonstrate how early canopy closure maintains a lower soil temperature.

With nodules performing optimally at 72 degrees Fahrenheit, cooler soil temperatures provide an agronomic advantage. More efficient nodules can supply a greater amount of nitrogen (N), which is critical as soybeans require 5 pounds of N to produce each bushel. The graph below demonstrates how closely yield and N availability align based on planting date. The earlier planting dates led to greater N content in the tissue and, thus, greater yields.

Planting early can make a big difference in your net return. This research not only illustrates that the optimum planting date for soybeans continues to trend earlier, but also that significant losses can occur when planting soybeans just one month later than the optimum planting window.

In summary, early planting pays. Be sure to consult your trusted advisor to determine what planting date is right for your operation.

The original content of this article was authored by Alexandra Knight, Beck’s PFR Agronomist in Ohio. Additional content and edits were provided by Chad Kalaher, Beck’s Field Agronomist in East-Central Illinois. PFR Practical Farm Research® is a registered trademark and PFR™ is a trademark of Beck’s Superior Hybrids, Inc.

For regional data on this study, check out the links below to Beck’s 2016 Practical Farm Research Book.
2016 Indiana Results 
2016 Kentucky Results
2016 Central Illinois Results
2016 Southern Illinois Results 
2016 Ohio Results 
2016 Iowa Results

Chad Kalaher is an agronomist in East-Central Illinois at Beck’s Hybrids and a Farm Management Advisor in the Midwest. He is a 2017 Illinois Soybean Association CCA Soy Envoy.