Soil Foodweb Incorporated
Soil Foodweb measures the quality and quantity of vital organisms in the soil and provides guidance in how to build your soil so your soil can build your plants.

Soil Quality Institute
The Soil Quality Institute identifies soil quality research findings and practical technologies that help conserve and improve soil, and enhance farming, ranching, forestry, and gardening enterprises. The Institute works with researchers, conservationists, and land managers to develop these technologies and make them readily available.

U.S. Composting Council 
The USCC is a not-for-profit organization dedicated to the development, expansion and promotion of the composting industry based upon science, principles of sustainability, and economic viability.

Compost Guide
This site provides a wealth of informatin about composting, with discreet links to commercial sites offering composting products.