Later-Planted Corn Yields Could Nose Dive

Plants can't make ears with no water.

Published on: Oct 1, 2007

More plots in the Farm Progress Corn Illustrated plot project were harvested recently. The hand-planted plots on non-irrigated ground were harvest on Sept. 21 by staff manning Beck's Hybrids plot harvest combine. It's a sophisticated machine that can harvest two, two-row plots at once, recording weight, moisture and usually test weight, all at the same time for each plot. Farm Progress offers a hat tip to Beck's Hybrids, Atlanta, Ind., for allowing their crew to bring their specialized machine and harvest hand-planted plots on the Jim Facemire farm near Edinburgh, Ind.

If you've followed progress of the plot, you know extremely dry weather and very warm temperatures, especially in August and early September, plagued the plot. The soil there consists of three feet of medium, loamy soil over gravel. The loam soil is ideal for starting and growing crops, but only if water comes along later once roots use up moisture in the first three feet of soil, and hit the gravel layer. There's a reason why soil judgers consider 'coarse sand and gravel' a limiting layer. There's also a reason why a gravel company owns the field.

In '06, yields were nearly double on the same kind of land. Top yield in the nitrogen-rate plot next to the hand-planted plots this year was roughly 90 bushels per acre, pending final calculations. Last year corn yields there were 150 to 190 bushels per acre. "You can't grow corn without rain- it's that simple," says Dave Nanda, president of Bird Hybrids, LLC., Tiffin, Ohio, and consultant for the Farm Progress Corn Illustrated plots.

One of the tests in the hand-planted area, consisting of about 0.2 acres, was a date of planting study. The same hybrid, a conventional, high-yielding hybrid without traits, sold by Bird Hybrids LLC., was planted at 10 different times, beginning May 1 and continuing until June 1.

Surprisingly, as late as early August, the late-planted corn looked very green and healthy. Nanda suspected that since it was a small area of late-planted corn, it might act as a trap crop, attracting rootworm beetles so well that it might need to be sprayed with an insecticide to prevent silk clipping. For whatever reason, that didn't prove necessary. There were a few rootworm beetles present, but silk clipping short enough to have caused a problem was never an issue. Bob Nielsen, Purdue University Extension corn specialist, suggests that it can become economically feasible to treat corn with an insecticide for silk clipping is silks are clipped back to within one-half inch, and pollination is still underway. That situation never occurred here.

What did occur after early August was a continuation of searing, hot days with no rain. Less than 0.5 inch was recorded at the site during the entire month of August, through Sept. 6.
Weather records provided by Ken Scheeringa of the Indiana state climate office confirm that the location was on the edge of drought all season long. Early in '07, a drought divide set up across Indiana so that the northern half got rain, while the southern half got less. Then mid-season it switched to provide significantly more rain on the western side than the eastern side. Finally, it switched back to north-south, with northern Indiana getting ample rain in many locations in August, but with southern Indiana staying dry,. The plots are on the edge of the area which stayed in drought mode all season long, during both shifts. Couple that with three feet to gravel, and ti was more than even the best of modern hybrids currently on the market could handle.

So while the later-planted corn looked good early, it fell apart later. By harvest day, ears were very small, and there were barren plants. Some corn lodged. While final results aren't in yet, it's nearly a cinch that the latest planting dates, while they still looked good when earlier corn went south, won't out perform earlier plantings.

Stay tuned. Once the data comes in, you'll know if the hunch is right, and if the data confirms that the latest-planted corn that ran out of water simply couldn't find enough moisture to sustain itself and still fill out a decent ear.