Minnesota Crop News > 2001-2008 Archives
Grain Drying Rates
Agronomy and Plant Genetics
University of Minnesota
Drying costs will be higher this fall because LPGas prices
have and are rising quickly during the past few weeks.
Corn growers may want to delay harvest to allow for more
field drying which could reduce drying costs. How much
field drying can be expected?
Field drying is an evaporative process of moisture moving
out of kernels through the husks. High temperature and
low humidity are the primary factors, which drive the rate
of field drying. Husk looseness is an important plant characteristic
that helps to speed kernel moisture loss. Other factors
are wind speed and sunshine hours that contribute to field
On average for the state, corn is physiologically mature
September 19 when grain is about 32 percent moisture. During
the last half of September, grain can lose 3/4 to 1- percent
moisture per day, depending upon the conditions, primarily
air temperature. Using 3/4% per day for the last 10 days
of September, grain should drop about 7.5 points or dry
to 24.5% moisture by the end of September.
During the first half of October, grain usually loses
1/2 to 3/4% per day. Using 1/2% per day, grain should drop
another 7.5 points during the first half of October, getting
the moisture content down to about 17%.
During the last half of October, the moisture loss can
be 1/4 to 1/2% per day. Kernel moisture content rarely
drops during November because air temperatures are so low.
For corn that reaches maturity before September 19, there
will be more days with the higher rate of kernel moisture
loss and more time for field drying. For corn that matures
later, there is less opportunity for field drying because
drying rates are lower and there are fewer calendar days
for drying and harvesting.
The tradeoff of delaying harvest to allow for more field
drying could be 1) increased preharvest losses due to dropped
ears (corn borer tunneling in the shank), 2) the weather
risk due to less calendar time to harvest, and 3) less
time after harvest for other field operations such as fertilizer
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