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October
7, 2004
Storing Shelled
Corn in Bags
Despite the warm days
in September, the unseasonably cool temperatures during summer 2004 means
much of the corn crop will not reach harvest maturity, so some North Dakota
farmers will need to store their crop as high-moisture corn.
“Using a plastic
silage bag is one method for temporary storage,” according to J.W.
Schroeder, North Dakota State University Extension dairy specialist. “If
it will work then becomes the question. Research on this topic is not
common, but actual experience is plentiful.”
A reference by B.Wilcke
from the University of Minnesota has these observations:
- If corn is put
into the bag at high moisture (25 percent to 30 percent) and the outdoor
temperature is relatively warm, naturally occurring bacteria cause fermentation
and the corn is ensiled. The bacteria consume oxygen and some corn dry
matter and produce carbon dioxide and organic acids as byproducts. This
low-oxygen, high-carbon dioxide, acidic environment preserves the crop
and protects it from deterioration by fungi (commonly called molds).
But if the bag is opened either intentionally or accidentally, oxygen
will enter the bag and mold will grow on the wet corn.
- If the corn is
damp (16 percent to 20 percent moisture) and the temperature is warm,
bacteria won't grow (it needs high moisture levels), but fungi (molds)
will. Fungi consume oxygen and produce carbon dioxide, but they don't
produce the grain-preserving acids that bacteria produce. Presence of
fungi on corn kernels (called mold damage) reduces the corn's feed and
commercial value. If the bag remains airtight, it is possible that the
molds will eventually stop growing as they reduce oxygen levels and
raise carbon dioxide levels in the bag. We don't have sufficient experience
yet to know whether there will be enough mold damage before the oxygen
is consumed to cause marketing or feeding problems. Experiments with
bagging and wrapping damp hay that is too dry for fermentation indicates
that if you can provide an airtight environment, you can often prevent
mold growth. Any openings in bags of damp corn will lead to mold growth.
- If the corn is
damp, but the temperature is low, neither bacteria nor molds will grow
very fast. This means that you can probably store damp corn in bags
through an Upper Midwest winter without too much mold damage. But because
the bags are long and narrow, they have a high surface area-to-volume
ratio and the corn will quickly warm to outdoor temperature in the spring.
As the corn temperature increases, mold will begin to grow and it will
be necessary to maintain a tight seal to limit oxygen entry and mold
damage. It might be possible to hold damp, bagged corn in warm weather,
but the risk of spoilage will be fairly high.
Based on corn storage
principles, here are some suggestions for producers who are considering
using silage bags for shelled corn storage:
- Dry shelled corn
is preferred, but if you store damp corn, fill bags late in the fall
and empty them by spring.
- The bags are easy
to fill, but difficult to unload. Use of a vacuum-type grain conveyor
is slow and labor intensive, so designing and building a machine that
features a large-diameter auger will make unloading faster and easier.
- Rodents (rats,
mice and squirrels) and birds will create holes in the bags. So check
the bags frequently and reseal holes immediately to prevent entry of
moisture and oxygen. Bags that are placed near rows of trees have more
damage from animals than bags that are stored on open ground. Check
the bags every week.
- Except for some
mold growth near holes in the bag, 19 percent moisture corn can be removed
in late winter and sold without discounts for mold damage.
- There is enough
damage to the plastic bags from rodents and from handling that they
can only be used once. This means you will need to purchase new bags
and find a way to dispose of old bags every year.
- Although storing
corn in bags is an economical, temporary storage solution, recognize
that until we gain more experience and knowledge, storing shelled corn
in bags is a high-risk operation.
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Source:
J.W. Schroeder, (701) 231-7663, jw.schroeder@ndsu.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu
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