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DuPont Pioneer Safety Alert: Silo Gas Poisoning Risk Higher with Drought

Drought conditions and the resulting buildup of nitrates in barren corn plants heighten the possibility of silo gas. Silo gas, combination of nitrogen dioxide (NO2) and carbon dioxide (CO2), forms within a few hours up to three weeks after filling a silo or silage bag. To help limit excess nitrates when harvesting silage farmers should:

  • Wait 3-5 days after rainfall before harvesting corn plants
  • Have someone with you outside of the silo to go for help if needed
  • Fence off the silage-filling area to keep children and animals at a safe distance
  • Cut the plant higher than normal to avoid excess nitrates stored in the stalk; however, due to the drought chopping at a normal height may be necessary to maintain feed inventory
  • Consider using an inoculant, such as PioneerĀ® brand 11CFT and 11C33, to help reduce nitrate levels
  • Use extreme caution when working around silage within three weeks of harvest until nitrous gas dissipates
  • Ventilate the silo opening the chute door closest to the silage level
  • Ventilate feed rooms with fans and open windows and seal doors between the feed room and barn areas
  • Avoid puncturing silage bags and releasing gas
  • Seek immediate medical attention if you have been exposed to nitrous gas.
Diagram: silo gas formation
Silo gas, a combination of nitrogen dioxide and carbon dioxide, is heavier
than air and hovers close to the ground. Farmers harvesting and storing
silage are advised to use extreme caution and seek immediate medical
attention if exposed to any level of silo gas. More information is available at:
Source: Crawford et al., Cornell Miscellaneous Bulletin 37, Nitrate
in Forage Crops and Silage. Benefits, Hazards, Precautions.

Nitrogen dioxide (NO2) is heavier than air and toxic to humans and animals. The gas may be colorless, yellow, or reddish brown with an acrid, bleach-like smell. Unfortunately, gas odor is not a reliable indicator of the presence of nitrogen oxides. Symptoms of silo gas poisoning range from mild to severe and include severe irritation of the nose and throat, coughing, shortness of breath and vomiting. Exposure may lead to lethal fluid buildup in the lungs. Many victims may suffer relapses with pneumonia-like symptoms up to six weeks after exposure. Anyone exposed to silo gas must seek immediate medical attention.

For more information about nitrous gas danger go to: