Final Rows Planted at Corn Illustrated Plots

Range of one month in planting dates.

How much difference does it make if you plant corn on June 1 instead of May 1? When does the magic break occur where yield actually starts to occur? Is it a date you can pinpoint on the calendar? If so, how many bushels do you give up per day of delay? Some agronomists say yield potential begins to slip after May 10, others say after May 15. Some say it starts out as a bushel of lost potential per day, then escalates to 1.5 bushels per acre per day.

Indiana Prairie Farmer's Tom J. Bechman, consultant Dave Nanda and Jim Facemire, the farmer hosting the Corn Illustrated plots near Edinburgh, Ind., hope to answer these questions more fully than was possible in the past. Corn Illustrated is a new section that will appear in all Farm Progress magazines across the Midwest four times per year. The first edition debuted in May. The next section will appear in the August issue. Content will be strongly tied to what's learned in these exclusive plots in the field.

To try to pinpoint answers to these original questions, Bechman and Nanda began hand-planting 1/1000th acre plots May 1. Then Bechman continued planting the same hybrid, a control for the test supplied by Bird Hybrids LLC, Tiffin, Ohio, for a full month. He planted at 10 different planting dates, including May 1, May 3, May 7, May 11, May 15, May 17, May 21, May 24, May 29 and June 1. A minimum of two 1/1000th acre rows were planted at each time.

Planting was done with a hand planter once used widely by plant breeders, Nanda notes. Facemire marked the rows with his corn planter by driving through the area with the planter down, but with row units shut off. Then Nanda and Bechman, and Bechman's son, Daniel, used the hand planters to place seeds at a uniform depth, approximately 6-inches apart.

Organizers are hoping to find the point at which yield actually begins to tail off. They also want to notice how plant characteristics change. The same hybrid planted later usually makes adjustments so that it can mature 200 heat units faster than normal. Sometimes that's accomplished by producing one fewer leaf, Nanda notes. The team of Corn Illustrated workers will watch closely for changes in plant characteristics, such as number of leaves, height of plants, and the like to see how planting date might affect expression of certain traits.

But the real test will be yield. The intention is to take this trial to yield to discover where a yield dip actually occurs.

Last Friday, June 1, when the last three rows were planted, the earliest-planted corn was already at about the six-leaf stage. In fact, Nanda checked plants planted on the earliest date last week and determined that growing points were already above the ground. Normally, conventional wisdom says growing points come aboveground around the five to six leaf stage. These seemed to be developing just slightly faster than usual.

Facemire, the farmer, makes a valid point, however. "This will tell me where the yield break was for this field in this year, in this weather pattern," he says. "But next year might be different.

While Nanda acknowledges that's true, he still sees value in trying to pinpoint when yield potential begins to fade. If you can get a couple good years of data from it, you can start to see trends," he concludes.

All plots were photographed on June 1. Going from the six-leaf May 1 corn to the rows just planted, with nothing but a dandelion or two showing in the plot, presented a stark contrast. Stay tuned for later updates.

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