Corn breakage increases with more drying
The 2008 corn crop is wetter and lower in test weight than average corn. Long, cool growing seasons produce high yields but the corn is wet and soft, with more soft white starch. This means lower test weight, and reduced storability as mold can invade the softer textured kernels more rapidly. It also takes more energy to remove water from softer corn.
Many farmers and elevators are taking from eight up to 10 percentage points of moisture out of corn. If done with heat, the corn will inevitably be more sensitive to handling breakage, and create dust or fines. Broken corn is also more susceptible to molding. Reports of nearly 10% broken corn have come in. The long term average is about three to five percent. Taking precautionary actions will reduce loss due to these conditions. Remember to wear a two-strap dust mask in dusty conditions as a personal safety precaution; dust, and potential fire hazards will be increased this year.
Rapid transition from heat to cool aggravates the breakage problem. Each subsequent handling causes more broken grains; it is almost impossible to keep up by cleaning the corn. Cleaning before the dryer will not help very much because most of the breakage happens when the dry corn is handled. Try not to let the corn (not the air) temperature exceed 140 degrees Fahrenheit and cool more slowly in a bin rather than in the dryer column. This will also increase dryer capacity by about one to two percentage points of moisture.
In the last few years, corn quality was good and handling system problems did not show up. Places where grain hits solid surfaces (elbows in piping, misaligned or worn spouts, slide gates not smooth, etc.) are points where breakage happens most. Cushion boxes and dropping grain on grain helps. The breakage in a grain on grain impact is about 50% to 70% of the breakage in the same impact with a solid surface.
Limit drop heights to less than 40 feet. This may mean not emptying bins completely, or using flow retarders that choke the grain flow periodically and take away momentum. A pipe with holes is often used for outdoor piles; the pipe fills up to whatever height is needed to make the flow out of the holes keep up with the loading rate.
Take a careful inspection of handling systems. Worn parts will show up this year. Augers are particularly hard on grain when the flighting wears and becomes sharp. Reduce chain and auger speeds where possible. Be very careful of bends and elbows in pneumatic conveyors; the breakage rate goes up rapidly with grain speed and corners in these systems. In all cases running handling equipment slower but fuller is better than fast and partially full.
If cleaning is necessary to make grade or for storage reasons, 3/16 square mesh screens will remove most of the small pieces. Some rotary cleaners use one-fourth inch screens; this will take out nearly all broken grains and some small kernels as well. If you are feeding the fines directly, then the additional removal may be worthwhile to gain storage quality. Integrate the cleaner into the regular handling path to storage, in order not to create additional handling. The benefits in airflow increase, and storage quality of corn cleaner than the allowable grade limit will likely outweigh the cost of cleaning and the loss of corn weight, if the cleanings can be fed locally.