Compost is full of living things (microorganisms, 
earthworms, insects, and other creatures) that need air, 
water, and nutrients to function. A compost pile needs to 
be fluffy so that there are plenty of spaces (what 
scientists call pores) for air to move about. Occasionally 
turning your pile refluffs the material, moves new material 
into the center, and helps improve airflow into the pile 
Compost microbes also need the right amount of water. Too 
much moisture reduces airflow, causes temperatures to fall, 
and can make the pile smell bad; too little water slows 
decomposition and prevents the pile from heating.