Picking Right Planting Date as Important as Planting Early

Now just find the right date!

Published on: Dec 10, 2007

An exclusive, intensive search for the most profitable day to plant corn in 2007 near Edinburgh, Ind., clearly indicated that the date was May 11. Final yields will be revealed in the February Corn Illustrated section in your Farm Progress publication. But suffice it to say that the May 11 date, under very droughty conditions on a water-challenged soil, far and away produced more corn than the same hybrid planted at any of the other seven planting dates in the study.

This was just one of a number of special, small-plot demonstrations that were planted and monitored during the first season of the Corn Illustrated plots. Jim Facemire is the host farmer. Dave Nanda, long-time plant breeder and president of Bird Hybrids, LLC, Tiffin, Ohio, serves as consultant.

Now, let’s break down what the finding does or doesn’t mean in terms of how you should prepare for the coming corn planting season. First, note this was a demonstration, not a replicated test. Two to four 1/1000th acre rows of the same hybrid were planted at each of eight planting dates, starting May 7 and continuing every three to five days. The objective was to determine the exact best date for planting. Agronomists once considered that yield began to drop after May 15. Now some say yield begins to drop after May 10, then deteriorates at an even more rapid pace for corn planted in late May or even later.

Second, a fair question is ‘Why not plant earlier?’ Actually, the original first two dates were May 1 and May 3. But even though sophisticated equipment was used to harvest the plot, a snafu in technology ‘ate’ the data for those first two plots. Based on other plantings of the same hybrid at the same dates in the same location, it’s likely they would have been similar to the May 7 planting, some two dozen bushels or more behind the May 11 planting. But because populations weren’t always the same in the other tests, Nanda preferred not to include those two dates in the observations here.

Third, note that the opening sentence says ‘most profitable date for 2007.’ This may or may not have any correlation to what might happen in 2008. It’s a snapshot of what happened in 2007, given weather conditions during that season. However, if the demonstration is repeated in enough seasons over enough different weather environments, a pattern may begin to emerge. In this case, past experience indicates there is usually a best time and a worst time to plant, maybe a stretch of two to three days each, in almost any season. The trick is determining when that is before the fact, not after it.

Fourth, note that the opening sentence also specifies the location. Since weather patterns vary, and did so particularly this year, and since latitude across the Corn Belt affects typical planting dates in any given area, these observations apply only to this one location, on this one soil. Again, however, if the trend shows up elsewhere, it may prove to be meaningful.

So why did corn planted May 11 excel? Nanda is still looking for that answer. But he’s convinced it wasn’t a quirk in the data. The May 11 rows got off to a faster start, quickly caught the May 7 planting, and looked healthy all season, at least until tremendous stress took its toll. It’s also possible, he notes, that since harvest population varied, these plots might actually have been favored slightly by less population in a dry year.

What he suspects, though, is that something in the microclimate, either a shower at the right time or more favorable temperatures at the right time vs. other planting dates, or a combination of things, made May 11 the ideal date for last year at Edinburgh, Ind. Stay tuned for more details.