Most people think of composting as a very "green" thing to do,
but few realize that composting actually generates a significant
amount of the potent greenhouse gases (GHG), methane and nitrous
oxide. Yes, composting is better than putting organic wastes
into a landfill, but it is not the ideal way to handle large
volume, organic waste-streams like animal manure. The better
option is anaerobic digestion which I will describe at the end
of this post. These Emissions Are Not A Scientific Surprise To a
microbiologist, it is not surprising that these gases would be
generated during composting. Methane and nitrous oxide are
formed by certain microbes when there is not enough oxygen
available (anaerobic conditions). In the middle of a large-scale
compost pile there are micro-sites without oxygen. This occurs
even in a pile turned frequently for aeration. This is
particularly true during the "hot" phase of the composting
process which kills pathogens and weed seeds. During the period
of very high oxygen demand, some