Alabama Corn: Yield Gain Potential from Harvesting High Moisture Grain

“Phantom yield gain” is a popular term for yield gains from harvesting high moisture corn (25-30% moisture) compared to letting the corn dry in the field (about 15-17% moisture) then harvesting it. Several studies in the Midwest Corn Belt show there is nothing phantom about these yield gains; they are real.

Dr. Bob Nielsen, Purdue University Professor of Agronomy, conducted an excellent four-year study of “Kernel Dry Weight Loss During Post-Maturity Drydown Intervals in Corn” in 1991-94. His conclusions in this study showed the physiological maturity of the corn kernels, defined as the point of maximum kernel dry weight, occurred at an average grain moisture content of 28.4%, and ranged from 25-35% during the course of the study.

His data suggests that the potential rate of yield loss averages nearly 1% per point decrease in grain moisture content. His example of mature grain allowed to dry down ten percentage points in the field (say, from 28% to 18% grain moisture content), the potential yield loss would be 10%.

The data reinforces the long-held concept by many high yield producers that the optimum grain content for harvest is near 25%. Corn harvested at higher moisture often results in damaged kernels while harvesting corn at moistures less than 25% often results in increased mechanical harvest yield losses (ear droppage, kernel shattering).

Dr. Nielsen also notes that seed respiration is another possible source of yield loss. Corn seed respires and uses its stored energy as it dries down. Corn seed respires at a higher rate with high temperature and humidity (the conditions we harvest corn under in the South). These “phantom yields losses” are greater if corn is subject to rewetting due rain and humid conditions during drydown.

The Alabama Corn Commission was gracious enough to fund an on-farm high moisture corn trial with Central Alabama Regional Extension Agent John Vanderford and myself on Stanley Walters’ farm in the Blackbelt. We wanted to see if not only if there was a yield gain from harvesting high moisture corn but was it economical for the grower to do it.

The trial was irrigated and replicated four times. The March 26 planted corn was harvested on August 5 at 24.92% moisture and the average yield was 210.74 bushels per acre. Thirteen days later (August 18) the corn was harvested at 16.95% (the corn averaged drying down 0.61% per day or about 8% total) and averaged 198.68 bushels per acre.

Both harvest weights were adjusted for moisture and yields are based on 15.5% moisture. The yield increase after adjusting for moisture was about 12 bushels per acre or 6%.

AgFax Weed Solutions

It takes 0.02 gallons of propane to remove one point of moisture per bushel of corn. I received three prices from farmers for propane, those that could buy it in bulk ranged from 80-90 cents per gallon and a price of $1.24 per gallon if propane is delivered to the farm not in bulk.

Stanley sold his corn for $4.00 per bushel or $48.24 more per acre when harvesting at 25% moisture compared to 17%. The drying costs ranged from $26.87-41.65 per acre so a grower with his own dryer would have averaged $6.59-21.37 more per acre depending on the price he or she would have paid for propane.

It would not have been economical for Stanley to have it dried by the grain buyer as the buyer charged 6 cents per bushel for every half of point of moisture removed below 20% and 8 cents per bushel for every half a point above 20%.

I did not consider two factors in my analysis. First, the capital expense of owning a dryer as I assumed ownership. Secondly, the value of getting the corn harvested two weeks early and minimizing the risks from bad weather and corn being blown down.

Those growers who have harvested lodged or down corn due to wind can attest to the value of harvesting early. Corn harvested at high moisture and getting started earlier is an excellent insurance policy.

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