Cold Composting vs Hot Comosting

Cold Composts vs Hot Composts

We made up the term "cold composting" but that's what happens if the temperature in the composting pile doesn't reach 165F. Why are temperatures above 160F desired?

Hot composting produces heat. On a cold day this heat may appear as steam coming from the composting pile like a warm indoor swimming pool when the outside door is open. Yes, compost temps can reach 165F or more but it only takes a little bit of heat and water to make this "steam" come from a compost pile. Think of your warm breath on a cold winter day.

Nearly all the bad pathogens are killed if temperatures are high enough for a long enough time. Thats part of the composting process to make them safe to handle. Temperatures above 160F for 30 minutes or longer kill all the pathogens living in manures added to compost. Including human manure.

How are composts biologically active?

By turning the piles or mixing them. This mixing spreads the beneficial microbes throughout the compost. Only the center of a compost pile gets hot. The outer edges are cool. The outer edges are where the good pathogens hang out. By turning the compost pile or mixing it, the previously hot compost that is now sterile gets reinfected with good pathogens where they repopulate it very quickly if their environment is warm and moist.

A good compost will be "biologically active". A good compost will be dark brown, crumbly and rich when you touch or smell it. Sometimes you can smell nitrogen rich ammonia coming from a rich compost. The smell of ammonia means the compost is so rich that it can't hold anymore nitrogen and so it "leaks" out of the compost into the air as ammonia.