Warm spring temperatures can cause the temperature of stored grain to increase, which in turn can lead to rapid increases in mold growth and insect activity. To limit mold and insect activity, you need to keep grain dry and cool. Make sure corn is less than 15% moisture, small grains less than 14% moisture, and soybeans less than 13% moisture for spring and summer storage, and try to hold the grain temperature at less than about 50°F.
If grain is not dry enough for safe storage, the first step is to either dry the grain or remove it from the bin. With adequate fan power on the bin (about 1 horsepower per 1000 bushels), you might be able to use unheated air to push a drying front through the bin before significant spoilage occurs. It's best if you can finish unheated air drying before May, or the grain is likely to get too warm and grain at the bottom of the bin is likely to get too dry. If you don't have large enough fans for drying, remove wet grain from the bin and feed it, sell it, or dry it quickly in a heated-air dryer.
For grain that is dry enough for safe storage, measure the grain temperature at several points in the bin. If you find temperature differences of more than 20°F between different parts of the bin, or if you find grain colder than 20°F, it is probably best to start the fan and run a temperature front completely through the bin. Make sure you leave the fan on long enough to complete the task; aeration time varies from a day or two for large drying fans to a week or more for small aeration fans. Continue to monitor grain temperatures while the fan is running and stop the fan as soon as the temperature front has moved through the entire grain depth. If you run fans in the spring, it is important to do it early&emdash;before average temperatures climb above 50°F.
Many grain managers do not run aeration fans in the spring and have no problems with grain going out of condition. This strategy works if stored grain temperatures are fairly uniform and if the grain is not too cold. But if there is a wide temperature range within the bin, moisture will migrate from warm grain to cold grain, resulting in condensation and possible spoilage. And any warm, humid, spring air that moves into the bin will condense on cold grain and again, spoilage could occur. Also, moving cold grain out of a bin on a warm day will result in condensation on the cold kernels, which could lead to handling problems, erroneous moisture meter readings, and possibly spoilage.
After you've made sure that stored grain is at the appropriate moisture and temperature, keep a close watch on it during warm weather (check bins at least once a week) and be prepared to take action if grain condition starts to deteriorate.
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