Management of Stored Grain With Aeration
Aeration is the practice of moving air through stored grain to reduce the rate of grain deterioration and prevent storage losses. Spoilage in stored grain is caused by mold growth and insect activity, which is related to the moisture content and temperature of the stored grain. Aeration greatly improves the “storability” of grain by maintaining a cool, uniform temperature throughout the storage to reduce mold development and insect activity and to prevent moisture migration.
Temperature differences in a bin of stored grain cause moisture to migrate from warmer areas to colder areas. Figure 1 shows moisture migration in a bin when grain temperature differences are created due to colder weather. The warm air rising in the center of the bin cools when it reaches the cold grain near the surface. This results in moisture condensation near the surface and leads to rapid spoilage when the weather turns warmer. Crusting on the surface of stored grain is a common symptom of moisture migration. Moisture can also migrate to colder grain near the bin walls during cold winter weather. It is also possible to get moisture migration inward if the outside temperature is warmer than the grain. This is usually not as serious as the moisture migration upward and outward during cold winter weather.
Temperature differences can be caused by changes in outside temperature while the grain is being delivered to the bin. The temperature of corn delivered to storage from a high-temperature dryer will vary due to temperature changes throughout the day or with weather changes. Aeration is necessary to equalize and maintain uniform temperatures throughout the storage.
Effect of Temperature on Storability
The effect of temperature and moisture content on the allowable storage time of shelled corn is given in table 1.
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