Late and Very Late Planting in 2019: a Request for Yields from Illinois Fields

The record-late planting of corn and soybeans in Illinois in 2019 provides a unique opportunity to try to get a handle on how planting date affected yields. The idea is to help us know better what to expect, and how to manage, if we have such late planting again.

We can think of the 2019 growing season as a “giant, unplanned, and involuntary experiment conducted by Illinois farmers.” No one wanted or expected this, but with thousands of fields planted late or very late, we can use planting dates and yields—if we get them from enough fields—to estimate how much effect late planting had on yields. We can also see if changing to an earlier-maturing corn hybrid (and maybe soybean variety) for late planting increased yield. It takes a large number of fields because variability among fields is so great that having only a few dozen yields from, say, the third week of June won’t give us a very sound estimate of yield.

We already have a fair amount of data from planned experiments in which we planted the same hybrid or variety in the same field over several dates. But we have not planted corn past early June or soybeans past mid-June in most of these trials, and so had little to go on when more than half of the corn and some 80% of the soybeans couldn’t be planted until after June 1 this year.

To have a chance to make this work, we need yields along with planting date, hybrid/variety maturity rating, and yield, from a lot of fields, representing a range of planting dates from early (April) to very late (late June or even July). Getting ten or more sets of field information from each of a dozen or more producers per county would be great. Getting a hundred or more from a seed dealer, agronomist, or other retailer who works with numbers of farmers would be even better. We’d like to get these by the end of December, but will continue to take them into January.

One easy way to submit information for this is online, using the anonymous form found here. With only eight things to fill in (including county and crop), we think it will take only a minute or so to do this for a field, once planting and harvest dates are on hand. You can also fill in information from a number of fields on the form found here. You fill in the form using a word processor and return it as an electronic file. Or you can fill it out by hand and scan and email it or can send it by U.S. Mail.

We’ve already gotten some data with yield filled in as “variable,” sometimes with a low-to-high range added. We appreciate that yields are variable, but we don’t have a way to use such data. It might be best to leave out fields like this, or to put in yield from a yield map (or an estimate made during harvest) from a uniform part of the field that you think represents the field.

We have no funding at the present for this work, but we believe it’s important enough that we’re willing to put in the effort to make it work. If we ever have another spring like the spring of 2019, having this information will give us a much better idea of how to deal with it and of what to expect.

This season, after the poor start, was a good one in much of Illinois, and yields were higher than many people expected given the late planting. We believe that this reflects the ability of today’s hybrids and varieties to produce high yields under a wide range of conditions, but will be thinking and more about this over the coming months.

Thanks to all who have sent data already and to those who will be sending in data over the next few weeks.