Storing grain safely
By Alberta Agriculture and Forestry
Oct. 2, 2015 - Safe storage of a crop depends on both the temperature of the grain and the moisture level it is stored at.
"Harvest has been difficult this fall - frequent showers have slowed the harvest and grain quality is suffering," says Harry Brook, crop specialist, Alberta Ag-Info Centre, Stettler. "No one has yet managed to control weather and that is the greatest risk of all. There might be a temptation to harvest damp or wet grain just to get it in the bin. This can work in the short term but the issue of wet grain has to be dealt with fairly quickly. Once it is in the bin is no time forget about it."
Here is a list of crops and the maximum moisture content they are considered to be "dry" at and safe to store.
- barley (feed)-14.8
- barley (malt)-13.5
- domestic mustard seed-10
- triticale -14
"This chart shows approximately how long damp grain can be stored safely in the bin," says Brook. "Be warned that deterioration can start to occur before the time expires. It still has to be either dried or aerated. Aeration requires warmer temperatures and low humidity, which is what we are currently lacking. Going into fall, temperatures will continue to decline, lengthening the time it takes to bring moisture levels down. Even dry, hot grain placed in a bin creates moisture migration. It takes time for grain to stop respiring and moisture to equalize in the bin."
The hot grain or oilseed creates circulation in the bin. Cold air outside will cool the grain against the bin sides and moisture will move down the outside of the bin, and then come up the middle.
"If there is any place for the moisture to accumulate, it will be in the middle of the bin, just below the top," explains Brook. "Green seed or immature seed in the bin may also contain more moisture and add to the problem. This is why it is imperative when harvesting hot grain to cool it quickly. Aeration under hot harvest temperatures is important to get the grain or oilseed temperature down to a safe storage level."
See a diagram of moisture migration in a bin.
In addition to the condition of the crop, hot grain in the bin acts as a beacon to cereal grain insects. Rusty grain beetles are good fliers and they home in on hot grain, infiltrating the bin and starting to breed in the high moisture zone.
"Warm conditions at harvest and multi-staged crops are potential ingredients for storage problems," adds Brook. "You've spent a lot of money and time getting the harvest in the bin. Take the time to monitor the stored grain condition and cool those bins down. Don't get an unpleasant surprise when selling the grain with discounts for heated grain or insect problems."
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