Dr. Dan Talks Agronomy

By Daniel Davidson
DTN Contributing Agronomist

Increasing yields without incurring additional costs is what it’s about in this economic climate. Planting corn earlier guarantees the best yield potential. However, environmental factors and management also enter the picture, but these also tend to take a bigger toll the later you plant.

Generally, I think of early corn planting as pushing the date up by at least 10 days from the traditional planting window. Crop insurance deadlines enter the equation, but the prolonged, wet planting season last spring will have many growers itching to get started earlier in 2016.

A report by economists from the University of Illinois says early planting works, but there’s more to the story. Research conducted by University of Illinois agronomist Emerson Nafziger shows planting before April 25 produced the highest overall yield, but it’s not necessarily a yield bump. Planting between April 25 and May 15 resulted in modest yield penalties as time progressed. Planting after May 15 resulted in the most severe yield penalties. This is not news to growers, and that’s why they make every effort to get planters rolling as early as possible.

In other words, the economists found that the yield penalty is larger for planting later than are the gains for planting early. The point is that early planting guarantees you the best yield potential in a field. As planting is delayed, penalties worsen and often significantly.

The authors agree that timely planting clearly influences corn yield prospects, but they emphasize that other factor probably play a bigger role in final yield. Purdue University agronomist Bob Nielsen is noted for stating: "The statewide (Indiana) statistical data suggest that planting date accounts for less than 25% of the variability in statewide yields from year to year."

Nielsen noted that yield potential declines not just because of the delay in planting, but the introduction of additional stress factors such as a shorter growing season, pollination when it is hotter and drier and possible increases in pest pressure. He points out that growers have to remember that yield loss associated with late planting should be attributed to two things; yield loss due relative to the maximum possible yield at the ideal planting date and yield loss due to additional stresses that are incurred.

In 2015, some corn was planted in April on the early side and easily weathered the heavy spring rainfall events. We also had corn planted far outside the April 20 to May 10 window that suffered more from too much rain in June and early July rather than just an unfortunate delay in planting.

You can read the full article "Early Planting and 2015 Corn Yield Prospects: How Much of an Increase?" authored by Scott Irwin, Darrel Good and John Newton at the University of Illinois here:


As Nielsen told DTN last year, growers also need to understand the consequences of rushing the season. "Adequate moisture and soil temperature and good seed-to-soil contact sound easy, but growers find it hard to wait, especially when they have a lot of acres to cover, especially if the previous season didn’t cooperate," Nielsen said. "I don’t care when you plant, just recognize the risk and consequences of cold soil temperatures."

If you have a question, e-mail Dr. Daniel Davidson at askdrdan@dtn.com