Burning piles of a different sort

Burning rangeland offers some unique challenges. Those of you who have conducted prescribed fires in the Great Plains have all been there, stomping out smoldering cow pies along the fireline.  And, many a spot fire has started as the result of a pile of smoldering animal dung.  From a fire safety and behavior standpoint, you may not want the fecal pats to burn, but burning them might provide for parasite control.  Larvae and eggs of undesirable livestock pests hang out in the delectable deposits and burning them up can be advantageous. Someone has finally gone through the trouble to learn what conditions render the piles of poo flammable.

Fecal pat flaming 2 hours after a burn. Photo by Derek Scasta.

Fecal pat flaming 2 hours after a burn. Photo by Derek Scasta.

Smoldering fecal pats. Photo by Derek Scasta.

Smoldering fecal pats. Photo by Derek Scasta.

The research team found that fecal pat condition (fresh and moist/fresh and dry/old and dry), fuel load, and 10-hr dead fuel moisture are strongest predictors of whether a pat will burn.  Roughly if 10-hr fuel moisture is >13% pats are unlikely to burn, but 40% of old dry pats burned at 13% dead fuel moisture.   To avoid combustion, the authors recommend burning in conditions with greater than 16% 10-hr dead fuel moisture.  If you are looking to reduce your parasite load, you may want to pick conditions that include 8-10% 10-hr dead fuel moisture in order to burn up the fecal pats. Greater fuel loads also contributed to greater rates of fecal pat combustion.

Fecal dependent flies (horn flies on the side of the body (Haematobia irritans) and face flies at the corner of the eye and from the forehead to the nose (Musca autumnalis)). Photo by Derek Scasta

Fecal dependent flies (horn flies on the side of the body (Haematobia irritans) and face flies at the corner of the eye and from the forehead to the nose (Musca autumnalis)). Photo by Derek Scasta

 

Scasta, Weir, Engle, and Carlson. 2014. Combustion of cattle fecal pats ignited by prescribed fire. Rangeland Ecology and Management 67:229-233.