Managing stored grain
In the third of a four part series, Milling and Grain take a closer look at the management of stored grain by Kirk Nelson, Director of Marketing and Sales, Behlen Mfg. Co. USA
ven with proper aeration, grain can only be stored for a limited time. It will deteriorate faster as temperature and moisture content increase. The allowable storage time is based on the length of time corn can be stored before losing 0.5 percent of dry matter. With this amount of dry matter decomposition, it is assumed that the
corn loses some quality. For each 10째 F (5째 C) increase in temperature, storage time is cut roughly in half when held at a given moisture content. Grain moisture content will change with relative humidity of the surrounding air and the grain temperature. Contact your local extension office for detailed information on stored grains. Under certain conditions, no matter how long the fan is operated, grain may not reach the desired moisture content that will allow it to be stored without spoilage. Keep in mind that air temperature and relative humidity are not constant. Use the daily average for determining final moisture content. It is recommended to use aeration when storing grain for short periods in a wet holding tank at various moisture contents. If no aeration is provided, grain may deteriorate much faster due to regions of higher temperatures that may begin to develop, producing heat and moisture that accelerate deterioration. The purpose of aeration is to reduce high temperature areas and to keep all grain at a constant temperature.
Grain spoilage can occur due to improper storage and management. One very common problem is that the grain moisture content is too high for the storage period. Or it may 66 | Milling and Grain
have been held too long without adequate aeration prior to drying. Alternatively it may not have been allowed to cool properly after drying. It must be dry and cool before storing. Even after this, aeration continues to be vital to control grain temperature. Another fundamental problem may simply be poor initial grain quality, including pockets of fines (broken kernels, weed seeds and trash) which restrict airflow and provide food for mould and insects. And of course, it is essential to properly control the insects themselves. Whatever else you do, grain must be checked on a periodic basis during storage.
The moisture content of grain storage
The length of time grain can be stored without aeration and the moisture content at which it is stored determines whether there will be significant deterioration. Short-term storage generally refers to winter storage. Long-term storage spans more seasons. You should contact your local extension office for recommended moisture contents and storage times. Grain should be dried to the moisture content required for the intended storage period and the type of grain stored. For best results, an accurate moisture test is needed to determine if the grain is dry enough.
An aeration system is necessary for controlling grain temperature in order to prevent grain loss. But aeration is not drying. A drying fan can be used for cooling if grain is stored in the bin in which it is dried. But if grain is to be placed into a different bin, it should be equipped with an aeration system to control the grain temperature during storage. It is imperative that the grain be cooled during storage to control insects and