The Dog Days of Composting

For mushers who worry about the mountain of dog manure that looks more like Denali with each daily yard cleaning, Ann Rippy has a suggestion---compost it.

Rippy, an agronomist with the Natural Resources Conservation Service in Fairbanks (formerly the Soil Conservation Service), shares the unique job of composting dog feces in an ongoing study that began in the summer of 1993. Rippy and technicians at the Fairbanks Water and Soil Conservation District received a $17,000 grant from the Environmental Protection Agency to help maintain local water quality, since many dog lots are on or near wetlands.

Rippy and other researchers worked with dog mushers within commuting distance of Fairbanks who were frustrated with dog yard build-up, or who were interested in using the compost as a high-nutrient soil amendment for the garden.

As is often the case with Alaska research, Rippy found little background material dealing with composting dog manure. However, she did find examples of ingenious methods for composting anything from grass clippings to dead chickens.

The stars of the compost show are one-celled organisms that heat up to incredible temperatures as they work. Bacteria, fungi and actinomycetes already living in the raw material feed on its organic content. In doing so, the little guys can heat up to as high as 200 degrees Fahrenheit. The actinomycetes ferment carbohydrates as they work, producing a wonderful, earthy fragrance more reminiscent of a freshly turned garden than a dog yard.

To find the perfect "recipe" for dog manure compost, Rippy and the other researchers had to determine how much carbon (wood chips or shredded straw) was needed to mix with the nitrogen source (dog manure). When an acceptable carbon/nitrogen ratio is used, the composting process goes much faster.

They conducted the experiment as follows: Mushers built their own composters out of hardware cloth, a wire screen with one-inch squares that let in plenty of microorganism-stimulating oxygen. The screen was shaped into a standing cylinder about two-and-one-half feet in diameter, and into that mushers dumped dog manure mixed with wood chips, straw or another carbon source. Rippy's recipe calls for two-parts dog waste, and one part carbon. When these two well-mixed ingredients were united in the screen bin, the microorganisms went to work.

Mushers monitored the temperature of the piles with long-stemmed thermometers; the perfect composting range is between an average of 130 to 170 degrees. When the temperature dropped below this range, the compost was turned to reintroduce oxygen and to assure that the waste on the outside of the pile got a chance to cook.

After about three turns, usually over a couple of weeks, the dog manure and carbon- source mixture looked, felt and smelled like compost, and it took up about half as much space as the raw material sitting in the dog yard or scattered in the woods. If, through further testing this summer, the compost proves it gets hot enough to kill Toxicara canis, or large roundworms (one of the most heat-resistant pathogens found in dog manure), Rippy said it would be approved for use on gardens.

Maybe then mushers can turn those mountains into useful molehills.