The Daily Evergreen, Washington State University’s daily newspaper, interviewed John Reganold, a WSU regents professor of crop and soil sciences, and Richard Finch, the compost manager at the WSU Compost Facility, regarding their opinions on the safety of composted manure:
“If people are using properly composted materials, they should be completely safe in organic farm applications or growing food crops,” said Richard Finch, the compost manager at the WSU Compost Facility.
At the WSU Compost Facility, manure is placed in long, symmetric rows where it begins a 10-week process of transforming into compost. The manure is mixed with straw and wood to increase the amount of oxygen mixing with the manure. In a week, the manure rises to a temperature of 130 degrees. Eventually, the manure will rise to as high as 170 degrees.
Department of Ecology regulations state the manure must remain between 130 and 170 degrees for a minimum of 15 days. The warm temperatures eliminate potential bacteria such as E. coli. To avoid runoff from unfavorable weather conditions, the compost rows are never more than 10 feet tall, Finch said. The rain and excess compost is also funneled into a pond to prevent it from contaminating irrigation water.