Drought-stressed corn silage ensiled in upright silos can present a safety concern. Faith Cullens, dairy extension educator with Michigan State University, reminds producers to use extra caution because of the nitrogen dioxide produced during silage fermentation.

This deadly gas is produced within two hours of ensiling and will be present for at least two to three weeks afterward. Concentrations as low as 25 parts per million are invisible, odorless and toxic to humans. At higher concentrations, the gas is yellowish-brown and smells like bleach. If it is necessary to enter a silo before three weeks of fermentation, run the blower fan for at least 30 minutes before entry, and leave it running while inside. It also is highly recommended to use a self-contained breathing apparatus.