Wallace's Farmer, IA
09-10-07
Tips for Storing and Handling This Year's Crop
Rod Swoboda rswoboda@farmprogress.com
Heavy rains and flooding in a number of fields late in the growing season have
had numerous impacts on crop production this year. Many effects will not be
completely clear until harvest starts; late season flooding is quite rare. Among the
management issues created by waterlogged fields late in the growing season will
be challenges in grain handling, storage and use.
"Fortunately, you have some choices in how you manage your grain after you
harvest it, and that can help," says Charles Hurburgh, director of the Iowa
Grain Quality Initiative and a professor of ag engineering at Iowa State
University. He offers the following advice on handling soybeans and corn.
Beans may be higher in moisture
Soybeans are likely to be higher in moisture content and they'll dry down more
slowly than in normal years. Any insect or other seed coat damage will magnify
the invasion of mold. The southern U.S. has this kind of weather more often than
the Midwest does, and you can see what's happened there in past years.
Tropical storms in the South generally have caused discoloration of soybeans
and mold activity, which in turn leads to further storage problems.
Expect to aerate your soybeans that come from flooded fields. Do not put them
into an unaerated structure with no possibility for temperature or moisture control.
Remember that the first grain harvested could be quite warm. Warm grain needs
to be cooled quickly.
Typically soybeans lose moisture rapidly even with low airflows, but these beans
will retain more moisture longer. If development is slowed, then there will be a
larger percentage of the wet elongated beans early in harvest. These beans will
store "wetter" than they test in electric moisture meters. A general rule for
storage management is to add 2 percentage points to readings if green or
elongated wet yellow beans are present in a sample. Aerate them down to at
least 12% moisture, especially if storage into spring is expected.
What if you get an early frost?
It is too early to anticipate frost, but an early frost would magnify the water
retention properties as well as add green color to any gray or brown mold
discoloration. Soybeans that are discolored enough to create discounts for the
total damage factor can be aerated for two to four weeks, and sometimes the
discolorations will partially subside.
Beans may be small if plant development is slowed. Small seeds aren't inherently
a problem for either storage or use. Expect variation in oil and protein however,
depending on the development stage at the time of the heavy rain. "On average,
I would expect 1% to 2% lower oil content than the average 19%. This is what
happened in 1993, the last year we had late season heavy rains," says Hurburgh.
Corn storage considerations
Post harvest quality of flooded corn is more uncertain than soybeans. The key
will be the degree to which grain fill and development is retarded by the excess
moisture. Generally, retardation in development before black layer will cause
higher sugar contents, softer kernels, lower test weights and poor drying/storage
properties. This will probably vary by field, which means the first grain harvest will
be your way to determine what happened.
Test weight will be the simplest indicator of overall quality. The best measure of
test weight is after drying; dry test weights that are below 54 lb. per bu. should be
considered higher storage risk. Sell or use this corn first, and be sure it is stored
in a structure with adequate aeration (0.2 cfm/bu or more).
Corn intended for spring and summer marketing should be at least 54 lb. per bu.
and preferably more. Progressively lower test weights are indicators of
progressively less mature and more stressed corn. Low test weight grain is more
prone to blue eye mold, which grows slowly in corn down to 14% moisture, at
warm temperatures.
Test weight increases about 0.25 lb. per bu. for each percentage point of
moisture removed if the corn is mature. Immature corn will have progressively
less test weight increase. Some lots in 1993 had test weights in the 40's when
wet, and still in the 40's when dry. For this reason, test weight discounts in wet
grain, rarely done in normal years, should be validated with actual dryer samples.
Frost date will be important in determining the extent to which floods create
immature corn. In 1993, there was an early frost as well as excess rain.
Decision making at harvest is crucial
At harvest, decision making is always crucial to preserve future storage life of
grain. Holding wet corn without aeration for a day or two before drying can
shorten the storage life by two to three months later on. Likewise failure to cool
grain immediately will reduce storage life.
This situation will be magnified in stressed corn. That's why you should assign
bins or other storage structures based on expected storage time and quality
assessment at harvest. Never mix old and new crop corn in the same storage
bin. Clean bins completely before harvest. If corn begins to heat or spoil, plan to
move it soon. Storage life can never be recovered; future problems will occur.
Immature corn will probably perform differently in ethanol plants, requiring
changes to enzyme mix and fermentation time. From an ethanol perspective, it
will be important not to compound the processing challenges with mold
deterioration. Decisions made at or just after harvest will make great differences
in the overall use of the 2007 corn crop.