A grain dryer, as its name would suggest, is a machine manufactured simply to dry grain. In the United States, this is commonly used for two main crops: corn and soybeans. The grain dryer is an expensive piece of equipment and not one many farmers have. Rather, they may use the services of a farming cooperative or rent one in some situations.
Most farmers try to avoid having to use a grain dryer, or at least try to use it very little, whenever possible. This is because of the added expense the additional step will involve. This is why farmers will leave the crops out in the field as long as they possibly dare in the fall. The dead plants will naturally dry out the corn and beans. However, harvest must be done before the plants start dropping the valuable crop.
However, a grain dryer can also be a valuable tool for large-scale farming operations. This is because it allows for earlier harvesting of at least some of the crop. Without advancements in grain dryer technology, that prolonged harvesting season, created by starting earlier, may not have been possible. In the long run, this can be a financial benefit to the farming operation.
A grain dryer is needed simply because of the moisture content inherent in both corn and soybeans in most cases. These crops, if not turned into dry grain, would rot or mold. Either way, the effects for both humans and animals who consumed such grain could be very detrimental, up to and including being fatal. Therefore, using a grain dryer becomes a food safety issue.
The crop is loaded into the grain dryer usually with the help of a grain auger. Once in the dryer, it is subjected to a high level of wind produced by fans and heat, produced by powerful heaters. The temperature of an activated dryer can approach the boiling point. The more air and heat passing through the dryer, the faster the grain will be dried. After that, the grain may be stored in a grain bin or grain silo until ready for further transport.
In some cases, grain may be dry enough to transport without needing a grain dryer to further dry it out. In other cases, the moisture content may be so low that simply allowing it to sit and air dry for a certain period of time will be sufficient enough to make it dry grain. In the end, the use of a dryer depends greatly upon the circumstances.