By Elizabeth Hawkins and Jason Hartschuh
Corn harvest progress in Ohio has been behind pace as field drying has been slower than expected. Currently only 29% of the corn crop has been harvested compared to a 5-year average of 49%. With the recent rainfall and colder temperatures in the forecast, it will become much more difficult to field dry corn creating a need to send high moisture corn to the dryer.
As the weather turns cooler, it can become much more difficult to manage wet grain. It also becomes more difficult to determine moisture since most moisture meters are not accurate when grain temperature falls below 40 F. In order to get an accurate moisture estimate, put a grain sample in a sealed container and let it warm to room temperature, and retest moisture. It is also recommended that you allow the corn coming out of the dryer to cool to room temperature before testing moisture, especially if the tester is kept in a cool area. Also, keep in mind that you may need to adjust harvest logistics to account for longer transport times since corn above 28% moisture may freeze together and corn between 24-27% moisture often binds and will not flow properly from wet storage bins and trucks. Corn at 30% moisture should only be stored for a maximum of 6 days before its quality will degrade at 50ºF.
Now comes the challenge of drying high moisture corn in high temperature dryers. The high moisture corn will spend more time in the dryer which increases chances of browning. Grain exposed to rapid temperature changes during fast drying and cooling is also at risk of stress cracks and broken kernels leading to a lower test weight and increased fines. At many elevators and end users, corn test weight discounts begin for any sample under 53.9 pounds per bushel. Many producers are experiencing stacked discounts for test weight, damage, and heat damage this fall. Most high temperature dryers are run at about 210-230º F. One way to reduce kernel damage in wet grain is to decrease the temperature below 200 F. Unfortunately, lower temperatures are not as efficient at drying. It takes 4,000 BTU to remove a pound of water at 150 F but only 2800 BTU at 200 F. Keeping dryer plenum temperatures as high as possible without damaging grain is ideal. Monitor the grain coming from the dryer for cracks and decrease temperatures until quality is maintained. Cooling grain effectively after drying is also important to quality. When hot grain is cooled rapidly to 30 or 40° F by the dryer, the risk of stress cracks increases. One way to manage grain quality when drying high moisture corn is by making two passes through a continuous flow dryer. The corn does not get as hot each time and cools quicker, but this method increases expense and grain drying logistical challenges. If your bins are large enough, aeration fans can be used to cool grain the rest of the way in bin to help maintain grain quality. By cooling grain in the bin, dryer efficiency can be improved by 15-25%. When cooling grain in the bin, condensation can become an additional concern. As temperatures decrease below 40 F, the chances of condensation forming when hot grain is put into storage bins to cool increases. As the condensation cools during freezing nighttime temperatures, vents may become iced over decreasing efficiency and risking damage to the bin roof. To avoid this, leave all access doors open or close with an elastic strap that can act as a pressure relief valve. The grain coming out of a high temperature dryer should be at 90-100 F to reduce the condensation potential.
For the producers who use natural air drying, managing high moisture corn will be much more complicated as air temperatures fall below 40 F. Once temperatures fall into the 30 to 40 F range, it will take over two months for this corn to dry in the field. In bin drying should not be attempted if corn is over 20% moisture. Below 20% moisture, the grain can be cooled to 20-30 F using aeration and maintained in the bin until spring temperatures are over 40 F. As temperatures warm in spring, further drying will become necessary to avoid spoilage. Grain storage time is highly dependent on grain moisture and temperature. This factsheet provides a table that can help you determine how long you can safely hold corn based on your conditions: https://extension.sdstate.edu/sites/default/files/2019-09/S-0003-53-Corn.pdf.
Another quality issue of concern is high moisture corn often has more fines due to more aggressive shelling and drying. These fines can cause issues in the dryer leading to a greater potential for dryer fires. This can be managed in a couple ways. First, fines produced in the combine can be removed using a grain cleaner before the grain enters the dryer. The dried high moisture corn is often much more fragile after drying so even if combine fines are removed there is still a major concern for in-bin fines. After cooling bins, they should be cored to remove fines that accumulated in the center of the bin. During coring, about half of the peak in the bin should be removed creating a cone. If a cone is not created, the grain is bridging and you should NOT ENTER the bin.
This season’s harvest is shaping up to be a challenging one. Please keep in mind that poor condition grain can pose a safety hazard at all stages of handling, so take caution this fall and winter as we bring this crop in.
Source : osu.edu