Don't let manure be your cause of death

August 28, 2007|By Jeff Semler

Last week my column dealt with safety at harvest. Today, we will deal with safety in and around the manure pit. Manure applications often follow harvest and prior to planting of fall crops.

In spite of growing efforts to create more awareness in health and safety in the farming community, fatalities due to manure pit accidents are still reported.

The causes seem to be a combination of: needs to enter manure storage; highly varied toxicity levels from manure pits; lack of information on why and when dangerous conditions exist; the need for more effective education; and safety procedures and practical reliable sensors to detect toxic gas conditions.

Manure in storage pits can release gases which can be toxic - hydrogen sulfide, cause irritation - ammonia, or cause oxygen deficient conditions. These gases, especially the toxic ones, can cause human deaths. Ammonia and hydrogen sulfide are some of the gases we are interested in.


Trace release of hydrogen sulfide is common, while rapid release has been reported when manure pits are being emptied. Hydrogen sulfide is also very corrosive; therefore, its production may result in equipment and building corrosion problems.

These confined-space hazards often claim multiple lives before anyone realizes there is a danger of manure gas. Manure pits can be oxygen-deficient, toxic and explosive.

As mentioned above, there are several gases in manure pits that are of primary concern:

· Hydrogen sulfide is a highly toxic gas that is heavier than air. It can cause dizziness, unconsciousness and death. At low concentrations, it may smell like rotten eggs, but at higher concentrations, it deadens the sense of smell so that no odor can be detected.

· Carbon dioxide is an odorless, tasteless gas that is heavier than air. It displaces the oxygen supply in the bloodstream, which can cause unconsciousness and death.

· Ammonia is a gas that is lighter than air. It has a pungent smell and can irritate the eyes and respiratory tract. Ammonia also displaces oxygen in the bloodstream.

· Methane is also a gas that is lighter than air. The primary hazard of methane gas is that it can create an explosive atmosphere. This gas also displaces oxygen.

So now that we know what the dangers are, what should we do?

Avoid entering manure storage areas if at all possible!!

Many deaths have occurred when people entered manure storage areas without proper safety precautions.

If you must enter a manure storage area, the following entry procedures as outlined by University of Illinois Extension Specialists will minimize, but not eliminate, the risks!

Recognize that conditions are of greatest risk when manure is agitated or moved. Movement and agitation increase the release of dangerous gases, sometimes several fold.

When agitating, pumping, or moving manure, take precautions to be sure that extra ventilation is provided to nearby areas (e.g., buildings over or near the manure storage).

Remove all people and all animals from buildings over pits before pit agitation.

If you must enter a pit, test before entering. Test the oxygen level to make sure that adequate oxygen is available. Also test for hydrogen sulfide, a particularly toxic gas, to be sure that concentrations are safe (less than 10 ppm).

Provide additional forced ventilation. Additional ventilation will increase oxygen and decrease hydrogen sulfide and other toxic gases.

Monitor conditions. Oxygen will be consumed while working in a manure storage area, and additional agitation from working can increase the toxic gas levels.

Monitor conditions while working.

Use a safety line. A worker in a confined space or manure storage area should wear a body harness with a safety line. The safety line should be held by enough people and/or a winch so that the worker can be pulled out of the area if a problem develops.

Wear a self-contained breathing apparatus. If oxygen levels are below the safe concentration or gases are present at toxic levels, use of a self-contained breathing apparatus is a must. The person using a respirator should be trained on the use of the mask. It is particularly important that the mask form a tight seal around the face.

Provide a clear escape path. Make it as easy as possible for the worker to exit the manure storage area quickly. Don't block the path with tools or objects.

Keep fire away. Methane gas is a byproduct of manure degradation, and it is flammable. Keep fire and other ignition sources such as electrical tools away from the manure storage area. Test the methane level with an explosion meter.

Know first aid. Someone on the site should be trained in CPR and first aid measures.

While many of us don't mind the smell of manure, the manure pit can present significant dangers.

Please practice the above safety rules and follow the guidelines below to warn others. Restrict pit access with fences and grates or metal grills. Additionally, post warning signs.

I trust you will implement and practice these procedures. As always, safety bulletins are available from the Extension office.

Jeff Semler is an Extension educator, specializing in agriculture and natural resources, for the University of Maryland Cooperative Extension. He is based in Washington County. He can be reached weekdays by telephone at 301-791-1404, ext. 25, or by e-mail at

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