• Soil Conditioner - The number one role of compost is as a soil conditioner. Clay soils tend to be poorly drained and have few pores for oxygen. Sandy soils have overly large pores which move water and nutrients rapidly away from the root zone of the plants.
  
  Adding large amounts of compost to garden soils will improve both clay and sand. In clays, compost will help form larger clumps which provide larger pore space. This will help to keep the soil aerated and help improve drainage. Also, it will encourage organisms such as earthworms that will tunnel through the soil.
  
  In sandy soils, large amounts of compost will effectively "clog" some of the pore space and provide a water absorbent element. Another problem with clay soils is that they have a poor electrical charge that does not bond with nutrients so they tend to leach away. The organic matter in compost has an excellent ability to hold onto nutrients and make them available to plant roots.

• Nutrient Source - Compost is not a fertilizer. Although there are some nutrients in compost, they are generally at very, very low levels. In fact, if the compost is not thoroughly decomposed at the time of application, it may actually use some of the nitrogen from the surrounding soil.

• Mulch - In some cases, compost, especially in a coarse textured form, may be used as a surface mulch. This is probably more commonly done in the vegetable garden rather than in decorative beds and borders. In a sense, the wood chips, shredded bark, cocoa bean hulls and other materials commonly used for decorative mulches are also on their way to becoming compost (passive composting).
  
  Regardless of what you use for mulch, it will have these properties:
   

  • Aesthetics - mulches will add a common look and feeling to the beds and borders
     

  • Water Conservation - a layer of mulch minimizes surface evaporation of water
     

  • Weed Control - mulch will make it difficult for annual weeds to emerge fully
     

  • Soil Temperature - some plants benefit from having their root systems cooler and mulch will help reduce soil temperatures.

• Intro to Composting
• Types of Composting
• Organisms
• Carbon:Nitrogen Ratio
• Site Selection
• Composting Bins
• Equipment
• Starting the Pile

• Maintaining the Pile
• Aeration
• Watering
• Finished Compost
• Using Compost
• Troubleshooting Problems
• Composting Terminology

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.