Wood Chips

• Woods chips add a source of carbon to the compost fertilizer and help the composting process along. Because they are not prone to compression, wood chips tend to improve the air circulation of compost piles. The oxygen stored in the wood also tends to increase bacterial activity, increasing the rate of decomposition. The wood chips themselves tend to compost slowly, requiring upwards of six months to break down fully. One important consideration when using wood chips is that they do not contain enough nitrogen for the bacteria involved, thus depleting the overall nitrogen content of the soil or compost.
  
  

Wood Ash

• Wood ash and sawdust are useful alternatives to wood chips, especially for short-term composting. The ash and saw dust are still capable of boosting microbial activity and provide the added benefit of containing high concentrations of potassium and other minerals. Ash made from hard woods, such as oak, will contain higher mineral concentration than ash from pine and other soft woods. Although wood ash may also act as a natural pesticide when added to mature compost, the ash will produce lye when wet. Thus, you should add the ash early on so that the high heat of the compost pile neutralizes the acids.
  
  

Other Woods and Wood Byproducts

• Commercially processed woods and cardboard can be composted. Cardboard that is shredded, wet and mixed in with other organic matter will compost over a period of several months. This type of composting is used primarily at the industrial level by cities and large-scale compost producers. Never use these types of products in your garden compost pile. They may contain many different chemicals and pesticides that are harmful to both plants and humans. After processing, this type of compost is primarily used for large-scale land and landfill restoration, rather than agriculture meant for animal or human consumption.
  
  

Dangers to Avoid

• Although wood composting offers many advantages to both the home gardener and city planner, consider several important factors when using wood as compost. Because wood chips can absorb a lot of water, a compost pile can dry out unless you monitor it constantly. Dryness inhibits bacterial growth and slows the composting process. Wood, especially pine, will also raise the pH level of the fertilizer, which can harm more-sensitive plant species. Wood chippers are expensive and may not be cost effective for the home gardener. You should avoid store-bought wood chips because, like other commercial products, they are likely to contain chemicals or other additives.