University of Missouri Extension

G1908, Reviewed October 1993

Fires in Agricultural Chemicals

David E. Baker
Department of Agricultural Engineering

With increased agricultural production, farmers are using more fertilizers and chemicals. This has caused new problems for firefighters due to the numerous types of chemicals used and the increase in chemical storage by farmers and suppliers.

Chemicals used by farmers and commercial applicators include: fertilizers and soil conditioners, soil fumigants, herbicides, pesticides, rodenticides, insecticides, fungicides, explosives, etc. Many of these chemicals release toxic fumes with little or no warning when exposed to fire. Most serious are the organic phosphates, such as parathion and malathion, and chlorinated hydrocarbons.

When fighting chemical fires, wear protective clothing, use a self-contained breathing apparatus (air paks) and have sufficient air available to complete the job. For additional protection, work on the upwind side of the fire.

Firefighters should spend more time with farmers and suppliers to plan in case of a fire. Trade names and formulations number in the thousands. Many of these are chemicals that are poisonous both for their intended to humans. Proper storage, hazard identification, established emergency procedures and firefighter training are extremely important.

Fighting fires involving agricultural chemicals

Firefighters responding to fires involving agricultural chemicals should follow these steps:


Although most fertilizers are quite stable, there have been problems of fires and explosions with materials such as ammonium nitrate.

Ammonium nitrate
Like other inorganic nitrates, ammonium nitrate is an oxidizing agent and will increase the intensity of fire. All grades of ammonium nitrate can be detonated if they are in the proper crystalline form, if the initiating source is sufficiently large or if they are heated under sufficient confinement. The degree of confinement necessary usually is greatest for the purest material.

Storage recommendations for bagged and bulk ammonium nitrate are published in NFPA number 490, "Code for the Storage of Ammonium Nitrate." The standard covers building construction, pile sizes, spacing and separation of ammonium nitrate from contaminating material that could increase its sensitivity during a fire. Also covered are flow, cleanliness of the storage area and precautions against ignition sources.

Fire fighting procedures for ammonium nitrate should include:

Anhydrous ammonia
Anhydrous ammonia can cause severe burns upon contact. Contact with the liquid ammonia also can cause loss of sight, severe injury of the respiratory membranes and varying degrees of irritation of skin, eyes and mucous membranes. For these reasons, use adequate body protection — a self-contained breathing apparatus with full face shields (air paks) and full protective clothing. If working around the shut-off valves, also wear rubber gloves and a rubber apron to protect your body from contact with liquid.

If you are exposed to liquid anhydrous ammonia, wash the exposed area with water for at least 15 minutes or until you receive medical attention.

Anhydrous ammonia fire fighting procedures should include:

Urea is classified as a non-flammable material by the Interstate Commerce Commission. Urea will not support combustion by itself but melts at a temperature of 534.2 degrees Fahrenheit. At temperatures higher than 534.2 degrees Fahrenheit, it begins to decompose, giving off mildly toxic fumes. For this reason, the toxicity hazard of urea is given as slightly dangerous.

Urea fire fighting procedures should include:

Phosphate fertilizer materials
Phosphate fertilizers commonly used and stored in blending plants (triple super phosphate, diammonium phosphate) will not support combustion and have a melting point in excess of 1500 degrees Celsius. Both of these are rated as slightly dangerous in toxicity.

Fire fighting procedures should include:

Potash fertilizer materials
Muriate of potash is the principal potassium-containing fertilizer used as a bulk blending ingredient. It is rated slightly dangerous as a fire and toxicity hazard.

Fire fighting procedures for muriate of potash is the same as for phosphate fertilizer.

Chemical fires

Fire in a warehouse or farm storage area where agricultural chemicals are stored may create a great hazard to fire fighters, inhabitants and livestock, because the possibility of poisoning is added to the usual fire hazards. In addition, if proper fire fighting procedure is not followed, water or chemicals used to fight the fire could easily spread contamination over a wide area. For this reason, planning and training for chemical fires are very important.


Fire planning and inspection for local fire departments

Post-fire clean-up

Personal precautions

Fire site


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