Because they reproduce so quickly under ideal conditions, microbes may deplete the available oxygen through their activity. Therefore, it is important to aerate your compost. You can aerate your compost by turning it. This directly incorporates oxygen into the pile. You can aerate by adding bulky items.
Bulky items provide air channels so that oxygen can flow into and through the compost.
Bulky items also keep the pile from settling and compacting, which could restrict oxygen flow. Bulky items include oak leaves, pine needles, chipped twigs, and straw. You can aerate by probing the pile with a piece of rebar or an aeration tool. Simply probe the devise in several places in the pile. This will create passageways for air to enter the pile.