Re: What are the effects of the presence of air in compost?

The majority of the transformation of the organic matter, i.e. leaves, 
branches, grass clippings, will be the result of bacteria, mold, and 
fungi. Basically, they operate w/ oxygen (aerobic) and w/o oxygen 
(anaerobic). Anaerobic respiration/metabolism is less efficient than 
aerobic respiration and results in acidic by-products thereby raising the 
pH of the compost mixture. For this reason, I would think that the compost 
mixture held w/o oxygen would decompose quicker due to the acidic nature 
of the decomposition products. Also, due to the high acidity, bleaching of 
the colors would occur and I would venture that the compost pile held w/o 
oxygen would have significantly less color than the pile held in an oxygen-
rich environment. Moreover, the by-products of anaerobic respiration, would 
produce an acidic, possibly vinegar-like smell while the pile held in 
oxygen would produce a musty, somewhat rotten smell. Hope this helps. Try 
www.asmusa.org for additional information on bacteria, yeasts, molds, and 
fungi.