The microorganisms in the compost pile function best when the materials are as damp as a wrung-out sponge and have many air passages. Extremes of sun or rain can adversely affect the balance of air and moisture in your pile. The air in the pile is usually used up faster than the moisture, so the materials must be turned or mixed up occasionallly to add air that will sustain high temperatures and control odor. Materials can be turned with a pitchfork, rake, or other garden tool.