Moderate fall temperatures helping corn quality, and dry-down

Moderate fall temperatures helping corn quality, and dry-down

What a difference warm, dry weather is making on corn grain drying down in fields this fall

A few weeks ago a cool and wet long range forecast meant that large volumes of wet grains would be coming out of the field, at highly variable quality. Well, that did not happen. Warm temperatures and low dewpoints (dry air) since Labor Day have completely changed the crop quality picture. While there are still instances of wet grain and areas with delayed harvest from early September rains, overall the Iowa corn and soybean crops have had a marked reversal from what we anticipated.

GOOD QUALITY CORN: The quality of this year's corn is good. One indicator is test weight. Elevators in Iowa say corn test weight is normal in most cases, from 55 to 57 pounds per bushel. In fields where diseases were an issue in 2015, test weight is a little lower.

That's how Iowa State University grain quality expert Charlie Hurburgh sums up this fall's harvest so far. He is a professor of ag engineering and director of the Iowa Grain Quality Initiative. He says moderate fall temperatures mean this year's corn crop will likely have good storage qualities. "I was skeptical earlier this fall, as harvest began," says Hurburgh. "The weather forecast was for a cool, wet fall in Iowa. But the temperature turned out to be moderate and it's been a dry fall, too, as rainfall has been below normal in most areas of the state."

Rapid dry-down of grain in fields has increased test weight
The rapid drydown of corn grain while still on the stalks standing in the field was driven by low humidity air. "This has also has increased corn test weights, a key measure of future storability," says Hurburgh. Much of the 2015 corn harvest will have to be stored a year or more. Farmers are harvesting a record Iowa corn crop this fall and are determined to store it until the price improves. That may take a while, he notes.

The emphasis now should be on long-term storage preparation, says Hurburgh. The most important action at harvest is to reduce the temperature of the harvested grain as much as possible. "We have had low dewpoints this fall, in the 30s and 40s, which will allow aeration to take grain temperatures down quickly, even if the grain is wet," he says. "Do not hold wet grain without aeration; this will use much of the grain's storage life very quickly."

Very important to reduce temperature of harvested grain
If grain is cold, it is not necessary to over-dry it. Don't take it below 15% moisture content for corn or 13% for soybeans in the fall. "Routine aeration of long-term stored grain may eventually over-dry the grain, but you should leave maximum revenue options open as long as possible," notes Hurburgh.


However, he is concerned about the standability issues of corn this fall. A lot of corn is coming out of the field in the high teens to low 20s for moisture content. But he says farmers will be better off harvesting corn a little wetter if it has stalkrot or other standability problems. You can dry the corn in your bin with these low propane prices, and that will help you avoid harvest losses in the field if you go ahead and harvest the wet corn grain with a combine and dry the corn down in the bin.

Diseases of corn in the 2015 growing season, particularly foliar diseases in August, and the very tall stalks created by this year's growing season, are creating trashier corn than normal this fall. Tall and fragile stalks as the corn is harvested, are putting large amounts of plant material through the combine.

More trash is in combine's grain tank with the corn this year
Trash in this case is likely to be pieces of cobs and plant pieces rather than fines from broken corn. Careful combine adjustments between harvesting fields of different hybrids will help to control these materials and help keep them out of the grain tank of the combine, but even careful combine adjustments may not be capable of complete removal, says Hurburgh.

Fines in the stored grain should be reduced by taking out the center core of corn after filling a bin. Because typical grain cleaners in farm handling systems are designed to remove more fines than cobs, leaves and stalk parts, elevators and users of the corn such as ethanol plants and other processors, will likely have to remove these materials, if that is necessary for their use of the corn. "The grain handling emphasis should now be on protecting the storage life of what has turned out to be a much more storable crop than expected before harvest," sums up Hurburgh.

The protein level in corn looks to be average so far, he says. It might drop a little in the later-harvested corn. "There is usually an inverse relationship between yields and protein levels," he says. "That's good news for ethanol plants as they use the starch content of the kernel. But it's not as good for livestock producers who use corn for feed and for their corn to have a high protein content."

For more information on drying and handling grain for storage, visit the Iowa Grain Quality website at

TAGS: Soybean
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