Maximum Allowable Storage Time

% Moisture


# of Days

@ 40° F

# of Days

@ 50° F

# of Days

@ 60° F

# of Days

@ 70° F

# of Days

@ 80° F

13% 4,500 2,520 1,410 780 450
14% 1,800 1,020 570 330 180
15% 864 384 225 125 69
16% 763 339 151 85 47
18% 291 130 58 32 18
20% 144 64 29 16 9
22% 85 38 17 10 6
24% 57 26 11 7 4
28% 33 15 7 4 3

A common misconception is that grain can be held above 15% moisture without risking quality or loss of net income. To safely store corn post-harvest through the following spring, moisture content generally should not exceed 15%. To safely store through the fall, it should be no higher than 14%; and to store grain for one year or longer, it should be no more than 13% moisture. Small grains do not drop as much, but they should be targeted at least a point below 13% to hold more than a year.

Besides making sure your grain is dry enough for short- or long-term storage, here are other tips:
1. As grain enters the bin, run aeration fans to equalize kernel grain moisture, which typically takes five to 10 days. This puts the grain in the best shape to store safely.
2. Fines can’t be thrown as far as kernels. Repetitive coring that forms an inverted 10-foot cone for every 10 feet of depth as the bin is filled is a tremendous tool in minimizing fines in the center. It makes a major difference, increasing in value as bins get larger.
3. Soon after harvest, pull the bins with peaked grain down so the center is just below the corn at the wall. The grain will look somewhat like an “M” from the side, promoting air movement in the center. Leveling at this point is also a good practice.
4. Watch the ambient temperature, and use aeration fans to get the grain temperature below 50 degrees F as soon as possible. Nearly all insect and mold activity ceases below this temperature.
5. Don’t completely empty one bin at a time when it comes time to sell the grain. Instead, take partial amounts from multiple bins to form the “M” shape, and move the remaining grain around. That not only promotes air movement, but also reduces the risk of grain plugging the discharge.
6. Check the grain weekly. Climb to the top of the bin, without entering, and observe whether there is a crust or any noticeable smell. An increase in surface moisture usually is the first sign of problems.