Why does turning over a compost heap make the material decay more quickly?

Turning (aerating) your pile may mean all the difference between getting compost within 4-8 weeks or 3-8 months. Every pile needs a periodic influx of oxygen. If not, your compost heap may just sit there with the bacteria feeling rather sluggish. This anaerobic condition (meaning without air) means slower decomposition, lower temperatures, and possible odor, a potential problem with the Add-as-You-Go pile.