The warm spring temperatures following a warm winter may lead to stored grain problems, particularly for grain that exceeds the recommended storage moisture content or did not stay cool during the winter.
The storability of grain depends on the grain quality, moisture content and temperature, says Ken Hellevang, the North Dakota State University Extension Service's grain drying expert.
Grain moisture content must decrease as the grain temperature increases to store grain safely. For example, the allowable storage time of 17 percent moisture corn is about 280 days at 40 degrees, 75 days at 60 degrees and only 20 days at 80 degrees. Even 15 percent moisture corn has an allowable storage time of only about 70 days at 80 degrees.
Allowable storage time (AST) is cumulative, so because some of it was used last fall and during the winter, only a portion of the AST still remains. The goal should be to keep the grain as cool as possible, preferably below 40 degrees.
Due to the nice 2011 harvest season, some farmers only relied on field drying, and some corn was placed in the bin at moisture contents slightly above the recommended level for long-term storage. They either used or plan to use natural air-drying rather than drying the corn in a high-temperature dryer.
"This corn should be monitored and kept cool by running aeration fans at night or during times when outdoor temperatures are cooler than 40 degrees until the corn is dried," Hellevang advises. "Because grain spoils faster at warm temperatures, air-drying when average air temperatures exceed 70 degrees may result in spoiled grain before it gets dry. Unfortunately, the rate of spoilage increases faster than the rate of drying at warmer temperatures."
If fans were operated during the abnormally warm temperatures, continue to operate them to cool the grain. Average temperatures in the 50s or 60s are better when air-drying corn in the spring. The required airflow rate increases with warmer temperatures and moisture contents.
Stored grain temperature increases in the spring due to rising outdoor temperatures and solar heat gain on the bin. Solar energy produces more than twice as much heat gain on the south wall of a bin in early spring as it does during the summer. Air temperatures in the bin head space will be much warmer than the outdoor air temperature, which will heat the grain near the top surface.
Grain should be kept cool during spring and summer storage, Hellevang says.
Periodically run aeration fans to keep the grain temperature below 40 degrees during the spring.