In the case of heavier, denser, and

In the case of heavier, denser, and less porous mixtures such as wet manure and sawdust, aeration can be enhanced by building the piles/windrows on a base of porous material like woodchips at the base, and further enhanced by placing perforated pipes in the base. In this type of system, known as passively aerated composting, the compost is not turned. This requires very thorough initial mixing of the materials. This can be accomplished by passing the mixture through a manure spreader. Some farmers use a feed mixing wagon to mix compost. If the mixture contains manure, either power wash the mixer wagon before using it to mix feed, or dedicate the wagon for just mixing compost. After the mixture has been piled, cover the entire pile/windrow with a layer of finished compost, peat, mulch, or woodchips. This layer acts as insulation, which is needed to ensure uniform heating and decomposition throughout the whole pile/windrow. Using finished compost or peat as a cover is preferable because it can be incorporated with the compost pile/windrow without diminishing quality.Mulch and woodchips are not fully decomposed and would either need to be screened out or, if left in the mixture, the compost would need to be cured for a longer period of time.