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| A 70s vintage ISU extension bulletin I have titled "Profitable Corn Production," says 30 beats 36 or 38 consistently.
On this forum do a search for corn population vs rows. I've not detected a consensus on corn row widths. 20s and 22s tend to be hard to get through for side dressing and spraying but seem to be preferred in regions where beets are in the rotation to save on changing tractor widths and owning separate planters for the two crops. Some have converted from 20 back to 30 after a long time with the narrower rows, others that have compared tend to find advantages either way depending on the corn number and the year. I'm not sure those comparisons have been well replicated to take out local soil condition and weather effects besides corn number sensitivities. I suspect there are corn breeds that thrive in 20" rows and don't do as well in 30" rows and there are corn numbers that do just the opposite. A couple years ago I looked up ISU research on fertilizer rates for corn and found theses in the library that compared big jumps on N applications but never mentioned the corn variety which makes those studies useless in my book.
If the limit on corn yield is plants too close where a high population is needed for that yield, it would appear 30" rows would a limiting factor and 20" rows should be beneficial. I've seen such narrow rows near where I now live, but I haven't learned anything about their yield. They are in an ancient lake basin and have lots of composted turkey manure applied each spring. If plant to plant competition is a limit, then even narrower rows or seed put down in a hexagonal pattern with the seed in the center of a circle of area equal to 43560 / population should be best. It might be, and the differences may be too small to consistently measure and its almost sure to depend on the soil, its fertility, the weather, and the corn number.
In 2007 in 30" rows I planted three numbers at 34K population but with limited N. Two of the numbers were small areas because I ran out the preferred seed. One looked OK, the last one grew pop can ears, shart and half filled. Yet the overall yield was 173.2 bushel corn on 111 units of N (after poor beans) that was split applied.
Gerald J. | |
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36vs 30 vs 20 inch row spacing corn
