Safety in Silage Making and Storage
A well-managed silage operation will normally avoid the circumstances that can set the stage for an accident to occur. Always take time to anticipate injury and life-threatening situations.
- Silage cutters and blowers have parts that continue to rotate after the power-take off has stopped. Only when the tractor power is shut off and the machinery has stopped rotating can the operator check the sharpness of cutter knives or clear plugged material.
- In horizontal silos the surface of silage being packed by a tractor is soft and unstable. The silage next to a bunker wall and the sides of silage stacks are particularly prone to giving way under a tractor's weight. Steep slopes, or digging the drive wheels into silage, can lead to backward overturn. The packing tractor should have a rollover protection cab, and the operator should wear a seatbelt.
- When nitrates are degraded in the ensiling process, nitrogen oxides are formed as products of microbial metabolism. The NO2 which results when nitrogen monoxide contacts air is often called "silo gas" and is highly toxic to humans and animals when present in concentrations greater than 10 to 25 ppm. Always assume that both CO2 (carbon dioxide), which can asphyxiate a human, and NO2 (nitrogen dioxide), which is poisonous, are present in a tower silo. Pulmonary edema occurs when the gas combines with water in the lining of the respiratory tract, causing pneumonia-like symptoms and death. Even if exposure is not fatal, respiratory tract damage can occur. Relapses are common after apparent recovery.
Since NO2 is heavier than air, the brown gas is sometimes clearly visible inside silos or around silo openings. Most of the NO2 is evolved from the silage in the first week of fermentation, with production peaking at two to three days after ensiling. Production of NO2 essentially stops after the material has been in the silo for more than 10 days.
In one survey, 42 per cent of all silos tested contained NO2 concentrations high enough to be considered hazardous to human health. Silo gas, therefore, must be expected in silos. Precautions, such as never entering an upright silo without running the blower for at least 10 minutes to circulate the air and only entering with an approved breathing apparatus, should always be taken.