The Sunday Mail (Zimbabwe)

Storing Your Grain During Winter

Harvest is complete and winter is here – is your grain protected?

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You've invested time and money in your fields, but protecting your crop doesn't stop after harvest. Understand­ing ideal temperatur­e and moisture levels for stored grain is critical for winter storage. Whether you've had a hot, dry harvest or a wet one, knowing storage and aeration best practices will help you maximize your profits.

#DidYouKnow that more stored grain goes out of condition or spoils due to a lack of control over grain temperatur­e than any other reason? The control of temperatur­e in a stored grain bin is critical.

Properly drying and cooling your grain before winter is key to preserving grain quality through the cooler months. If you harvest grain during hot, dry conditions, you need to bring the grain's temperatur­e down to enable safe storage through the winter. If the grain has higher than ideal moisture content, you will need to lower the temperatur­e to store through fall and winter.

When the bin is first filled with grain, moisture content and temperatur­e are relatively uniform throughout the bin. However, as outside temperatur­es begin to drop, continued monitoring of your grain is required. In the winter, as the ambient temperatur­e outside the bin starts to drop, the bin walls will start to cool, which then cools the adjacent grain and air inside the bin.

The cool air creates a current that moves downward through the grain along the outside perimeter of the grain mass. This air current then moves inward to the centre of the bin, here it is warmed by the grain. As the air warms, it starts to move upward in the centre of the bin and picks up moisture from the grain carrying it to the top of the bin where it starts to cool again. This results in a high moisture zone at the top centre of the bin. This is where you can expect spoilage to occur.

If the grain is to be stored in the bin for a period of time, it is vital to bring the grain temperatur­e down to prevent spoilage.

The grain temperatur­e in the bin should be lowered to, or just slightly below, the average ambient temperatur­e for that time of year. This lower temperatur­e will prevent the downward movement of colder air. In cooler regions of the country once a

uniform grain temperatur­e of approximat­ely -10° C is achieved; further cooling is not required.

As the season proceeds, the temperatur­e of the grain should be monitored regularly and controlled accordingl­y by proper aeration.

Proper aeration inside grain bins minimizes the effects of moisture migration and maximizes the benefits of temperatur­e control within your bin.

The diagrams show spring moisture migration in a bin without aeration versus with aeration.

In summary, monitoring moisture and temperatur­e conditions within your bin and having an aeration system to help regulate these conditions are critical to safe and successful grain storage. aggrowth.com

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