By Kim Stonehouse, PAg, Crops Extension Specialist, Tisdale
There are a number of factors that contribute to how well and how long grain can be stored before it is delivered to the buyer. For the most part, the combination of moisture content and grain temperature at the time the bin is filled and during storage, are the key factors for grain safety.
In most years, uncured/green kernels and the physical size of the storage container have the potential to impact how well grain stores. This year, due to the late regrowth in fields, the addition of immature plant material was unavoidable in many places. This material could cause some significant problems down the road. Monitoring closely and addressing signs of spoilage promptly will be the only way to preserve grain quality.
It was not that long ago that the average bin size was 3,000 bushels or smaller. Today, bins larger than 5,000 bushels are common, with some as large as 50,000 bushels. With larger bins comes larger diameters. Bins with a smaller diameter tend to cool rapidly and have reduced potential for moisture migration to occur. While larger diameter bins can have a larger temperature differential that can remain unchanged for months, even though outside air temperatures have dropped significantly.
Even in bins where the grain has recorded an average safe storage moisture content, there can be pockets of higher moisture due to immature kernels and plant material or simply a variation in conditions during harvest. The combination of large temperature differentials and high-moisture pockets can lead to increased moisture migration creating problems with insects and moulds. For more information, check out Insects and Mould in Stored Grain.
To avoid moisture migration, it is best to cool grain down to within 5 C of the outside air temperature as quickly as possible. This equalizes the temperature in the bin and can be accomplished through operation of aeration systems or moving grain. As outside temperatures decrease you may wish to cool the grain again until the entire mass is close to 0 C for storage through the winter. The approximate temperature when insect activity stops is 10 C and cooler.
The key, of course, is monitoring. When grain temperatures are above 10 C, monitor on weekly basis for changes in grain temperature. Pay particular attention to the larger bins or bins with marginally dry grain. Once the grain gets close to 0 C, monitoring can be reduced to monthly.
It is important to note the relationship between moisture levels and temperature for every crop being stored. As either moisture or temperature rise, the length of time that grain can safely be stored is reduced, but the actual relationships are slightly different for different crops.
For more information on grain storage, contact your local crops extension specialist or the Agriculture Knowledge Centre at 1-866-457-2377.
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