New Compost Definition – Results From USCC Work with AAPFCO

Ron Alexander

Savannah, GA–The American Association of Plant and Food Control Officials has approved a new definition for compost that emphasizes the pathogen-removing thermophilic process, differentiating it from many products often confused as compost.

“This definition more completely defines what our products are so that people out there wanting to call their products compost cannot do that without meeting this definition,” said Ron Alexander of R. Alexander Associates, the USCC’s liaision to the AAFPCO, who has labored for years on the updated definition language. The new definition was adopted at the group’s winter meeting held in Savannah, GA last week.

The official definition is:

Compost – is the product manufactured through the controlled aerobic, biological decomposition of biodegradable materials. The product has undergone mesophilic and thermophilic temperatures, which significantly reduces the viability of pathogens and weed seeds, and stabilizes the carbon such that it is beneficial to plant growth. Compost is typically used as a soil amendment, but may also contribute plant nutrients.

The prior definition was: The biological decomposition of organic matter. It is accomplished by mixing and piling in such a way to promote aerobic and/or anaerobic decay. The process inhibits pathogens, viable weed seeds, and odors. (Official 1997)

“The USCC has been working on quality compost for 25 years, and we don’t want to have the compost industry’s product being confused with other products after all the work we’ve invested in best practices and quality product standards,” said Alexander, who spearheaded the AAPFCO workgroup that has worked for two years on the new definition.

The new definition also helps the makers of other products, from biochar to mulch to dehydrators and anaerobic digestate, to more clearly describe their products, as well.

The AAPFCO registers and regulates the distribution of fertilizer, soil amendments and liming agents. The groups members are made up of members of state agriculture departments. Some states automatically use AAPFCO’s definition in their definitions of compost; others can choose to amend their regulations with the updated definition, Alexander said.

The new definition is especially important because the compost manufacturing industry has worked hard to determine, train and educate producers about management practices such as process that use mesophilic and thermophilic temperature stages to reduce pathogens.