Question: Some years ago I heard discussions about injecting compressed air into compost pile either with a lance or a perforated pipe laid under the pile. Have you heard about doing this, and are there any problems with it?
Answer: Neither forced-air injection nor vacuum-induced aeration is recommended for the home gardener’s composting efforts because of the rigid and exacting requirements of these operations. Air can be introduced into the pile of decomposing material by periodic turning. As air flows through the composting mass it meets resistance: the finer the particles the more difficult it is to maintain proper aeration. Therefore, materials with large particles (like wood chips) should be added to the decomposing material. Oxygen must be available throughout the compost pile, if aerobic composting is to continue to completion.
Consider establishing two compost bins. Begin by layering the materials to be decomposed (plus fertilizer, soil, water, and lime) in the first bin. When it is time to turn the pile, lift the unrotted materials from the top of the first pile and dump them into the adjacent bin. Removing the finished compost from the bottom of the first bin empties it, leaving it ready to receive the top from the second bin when it is time to turn it again.
Working back and forth between the two bins ensures proper aeration, reduces the amount of labor involved, and results in good compost.