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