Grain Storage: Considerations to Maintain Quality: Part 1 - Introduction, What Is Aeration?
Mark A. Myers
The primary tools used to manage grain in bulk storage are Grain Temperature Detection Systems, and Aeration. A temperature detection system is an electronic reading device that is attached to special cables, suspended from the roof of the grain storage. A storage structure may have one, or many cables, depending on the structure diameter. The cables contain temperature sensors at approximately two-meter vertical intervals. Grain temperatures change relatively slowly, and are normally read and recorded once per week. Variations in grain temperature across the grain mass, or localized rising temperatures, can be indications of grain spoilage and the need for managers to take action. But since grain temperature detection is another complete presentation, we will not focus on it today. More importantly, we will focus on Aeration, the process of making changes within a grain mass.
Grain aeration basic principles are divided into four subjects: 1) What is aeration; 2) Why do you aerate grain; 3) When do you aerate grain; and 4) How do you aerate grain. An understanding of these four principles will significantly improve your ability to successfully store grain for an extended period of time.
What Is Aeration?
Aeration is the process of passing large volumes of ambient air through a grain mass, using a fan designed for that purpose, and an air delivery system. There are many designs on the air delivery systems. Most are designed into the concrete foundation of a grain storage structure, using a tunnel and a steel cover perforated with many small holes. Air is forced into the tunnel, through the perforated steel floor, and into the grain. The shape of an aeration system can take many forms, some of which are illustrated here a double, a "four system, or two rectangular pads. Aeration fans outside are connected to the aeration system inside. The type of system is not as important as the skill and experience of the designer, and the reputation of the manufacturer. Most are designed by the provider of the grain storage system, and meet critical design standards. Each system must be designed to provide adequate volumes and pressures of air for the quantity and depth of the stored grain. The size and type of aeration fan is also critical to successful performance of the system. Why Do You Aerate Grain?
Grain has enemies, including insects, mold and fungi, heat and moisture. Insects eat and breed in grain, creating damaged grain that will spoil and decay. Mold and fungi create heat and decay. Heat and decay nourish more mold and fungi. Moisture creates spoilage and decay, which creates more heat, spoilage and decay.
The purpose of aeration is to condition dry grain. It is not for the purpose of drying grain, as air volumes are too low to dry. Aerated, conditioned grain will decrease mold and fungi growth, decrease insect activity, equalize moisture deposits, and equalize heat distribution within the grain mass. Properly managed, aeration will improve your chances of successful storage.
Grain quality and condition can never be improved it can only be maintained. If spoiled grain is placed in storage, it cannot be retrieved or removed from storage in better condition. It is critically important that only grain in good condition be placed in storage. With good management, good quality grain can be retrieved from storage processing and used.
Consider the food in your home. Many fruits will spoil slowly if left out on the table. If placed in refrigeration, the decay is slowed. If cut open, the decay is accelerated. Grain is the same. In nature, grain has some natural protection. If broken, it decays faster. If kept cool and dry, it decays slower. Why aerate grain? Consider that grain is alive. If it is planted in the ground, it will grow. Like all living organisms, live grain breathes air and releases moisture. When contained in bag or bulk storage, the moisture can accumulate. Changes in temperature can create condensation. Moisture on the surface of grain will start decay and spoilage, which in turn will create heat and accelerate decay. The process of aeration a) equalizes moisture within the grain mass; and b) equalizes heat within the grain mass. Mold and fungi are present in the air and on surfaces wherever you are right now inside or outside of a building. Mold, fungi, heat, and moisture create spoilage and decay in grain. The process of aeration will equalize heat and moisture, and restrict the opportunity for growth of mold and fungi. The process of aeration will also limit the life cycle activity of insects that require moisture and comfortable temperatures.
Grain Storage: Considerations to Maintain Quality: Part 3 - When To Aerate Grain?, Aeration Rates, How To Aerate Grain, Aeration Front
Grain Storage: Considerations to Maintain Quality: Part 4 - Aeration Problems And Solutions
Grain Storage: Considerations to Maintain Quality: Part 5 - Conclusion