Thick Corn Holding Its Own With Rain

Higher populations hanging in there.

Published on: Aug 18, 2008

Walks through the Corn Illustrated plots near Edinburgh, Ind., last week showed that with rain, roughly 25 inches since planting, even 60,000 plants per acre looks good! Or at least it doesn't look too bad, yet. Stalks are smaller and ears shorter, but stalks are still standing, and it appears as if it will make a crop.

The 60,000 plants per acre is part of the narrow row and twin row corn experiment. Other parts of that test are at 30,000 and 40,000 plants per acre. The 60,000 was included as a comparison to show what happens with today's hybrids when you push population too far. Dave Nanda, consultant for Corn Illustrated, believes someday farmers may plant corn that thick. But it likely will be corn bred and developed just for such thick-planted situations.

Nanda checked chlorophyll readings on plots last week. As expected, the thicker plots, beginning at 40,000, generally posted lower chlorophyll readings per plant. That's because there was likely more competition for nitrogen, he notes. Some plants in the thicker plantings were showing signs of nitrogen deficiency. About 175 pounds of actual N were applied on these plots, which followed corn.

There were no apparent differences between chlorophyll readings based just upon row width difference, checked in 30-inch, 15-inch and 5-inch twin row patterns. Nanda will take a closer look at the data, but didn't see anything striking on first glance, he notes. He did see a difference between hybrids, with one of the two hybrids in the plot being visibly greener, and generally scoring higher in most of the combinations than the other hybrid. It's a hybrid that generally is darker green, Nanda says. Whether that corresponds with yield at harvest remains to be seen.

The chlorophyll meter for the testing was provided by Spectrum technologies, Plainfield, ill. It's designed as a measure of chlorophyll in the leaf. The machine produces numbers that are meaningful only when compared to one another. The theory is that if more nitrogen is in the plant, the leaves will be darker and the numbers higher. But there's not proof that plants with more chlorophyll in the leaves in July and August yield more in October, Nanda stresses.

Testing in earlier years seemed to correspond to this year's tests. The major difference detected in the past occurred only when populations varied widely. The higher the population, generally the lower the score, assuming N rates were equal. Again last week, plants that were obviously nitrogen deficient tested lower on the scale.