Fines, foreign material, and broken grain can create handling and storage problems. Grain breaks during harvesting and handling. Proper combine adjustment should be the first step to reduce the amount of fines and foreign material. Fine material has an affinity for moisture, molds, and insect infestations. Grain with fines also has a higher resistance to airflow than clean grain. When aerating stored grain or using natural air drying, clean grain makes the difference for uniform airflow and successful drying.
A grain cleaner located at the receiving area of the grain center can be used to improve storability. This is particularly important when storing wet, damaged, or immature grain. Producers should select a grain cleaner that collects and conveys screenings away with little attention from the operator.
Types of cleaners
These are generally simple cleaners which simply pass the grain over a screen during the handling process. Some are stand-alone units that are fed from an auger conveyor. Others are part of a permanent installation such as at the output of a bucket elevator.
A section of the auger housing is perforated and as the grain is conveyed over this section of the auger, the fines are separated. This type of cleaner has limited effectiveness when the auger is operated at 100% capacity. Unfortunately, when operating the auger at less than 100% capacity results in increased grain damage.
These cleaners simply use a rotating screen that tumbles and separates the fines from the grain stream. They can be very effective cleaners if properly sized and operated correctly. Consult the manufacturer for specific operating instructions.
Cleaning is easier and more complete at low flow rates and with dry grain. Cleaning can be accomplished after drying if the grain is to be dried and stored in separate bins. If the grain is not cleaned prior to drying, the operator should be prepared to spend more time cleaning the grain dryer. This maintenance is very important to maintain the capacity of the dryer and to reduce the possibility of fires.
Corn screenings are good feed. Feed wet screenings within a couple of days of collection. Take care when feeding fines from damaged grain. Moldy, soft, partially rotten grain particles are screened with fines and may have toxins harmful to livestock.
It is a good idea to make sure that the grain surface in the grain bin is level. Peaked grain will result in increased airflow resistance in the peaked portion of the bin. Furthermore, fine material in the grain tends to the center of the bin also results in increased airflow resistance.
Grain spreaders are useful to help eliminate this problem. Properly adjusted and operated grain spreaders will leave the top surface of the grain level with the fine material evenly distributed throughout the grain mass. The level surface and evenly distributed fine material results in a uniform airflow resistance throughout the bin.
The down side to using a grain spreader is that most spreaders tend to pack the grain tighter in the bin. At first thought this might seem like a good idea since more grain can be stored in each bin. However, this packing of the grain increases airflow resistance through the grain and the depth of the grain may need to be reduced to maintain airflow.
When storing grain with fine material and a grain spreader is not used, remove the center core of grain from the grain bin. Generally 5' to 8' diameter portion of the center core should be removed. (Consult AED-20, Managing Dry Grain in Storage, for the procedure of removing the core.) This core will contain a higher concentration of fine material and should be re-cleaned before being put back into the bin.