By Zachary Larson
Cooler weather means it’s time to monitor your grain bins to ensure that grain quality is kept throughout the storage period.
For many farms across the state, harvest has dragged into December and as of today some may still be filling their bins. But before calling this year a wrap and planning for 2019, it’s time to ensure that this year’s crop is properly stored. Regular monitoring of grain bins will ensure that you still have good quality grain when it comes time to fill a truck and send it off to market.
Storage problems often occur in grain bins due to inadequate cooling, resulting in condensation and crusted grain layers. Mold can result from high moisture content, excessive fines and damaged grain from high drying temperatures. Broken kernels can also be especially susceptible to insect feeding. When grain moisture increases, bacteria and fungi can decompose grain resulting in caking near the surface of the pile. Once grain is caked, bins can’t be effectively aerated without breaking up or removing the encrusted grain.
Grain is typically 15 to 30 percent moisture when placed in a bin. A dryer must then bring the moisture content down to 13% or less to minimize the impacts of insects, fungi, and bacteria. Temperature also influences the development of these organisms, with most insect reproduction and fungal growth halted below 50°F. Good targets for grain temperatures range from 40°F in the winter to 60°F in the summer. Aeration should begin when the average of the daily high and low temperatures is 10 to 15 degrees lower than the grain temperature. Final grain temperatures should be checked by sampling one foot into the upper surface of the grain. For aeration fans designed for typical cooling rates of 1/10 cfm/bu., this final cooling cycle may be up to 200 hours.
Monitoring of grain bins is essential to ensure that proper moisture and temperature is maintained. Grain bins are dynamic systems, and both can change throughout the storage period. Grain temperatures can be as high as 100°F, even in the winter. A grain bin should be monitored once a month during the winter and twice a month during warmer periods to measure grain temperature, moisture content, and insect and fungus activity. One should have on hand a grain temperature probe, a moisture probe and a tierer for checking for mold and insects.
After the grain is binned and leveled, a surface dressing can be applied to prevent insects from entering the grain surface. DDVP resin strips should also be hung in the head space to control Indian meal moth. Hot spots in the grain mass may indicate that insect populations are developing. If these are found, aeration should be initiated at once to lower the grain temperature and moisture content. Do not aerate on warm and/or moist days, as it can increase the two. If an infestation occurs despite these precautions, fumigation of the grain will be necessary. Due to the high toxicity and restricted classification of registered fumigants, a special applicator certification is needed for their proper and legal use. After grain is removed from the bin and it is properly cleaned, a residual spray can be applied to the bin walls and floor to prepare for next year’s crop. This practice is especially important if the grain will be stored for 9 months or more.