USDA. Natural Resources Conservation Service.
Soil Quality and Testing
National Center for Appropriate Technology. ATTRA - National Sustainable Agriculture Information Service.
Provides information about soil testing laboratories and supplies that meet the special needs of farmers using organic or sustainable production practices.
Virginia Cooperative Extension Service.
A guide for measuring, assessing and comparing laboratory and field test kit indicators of soil quality attributes.
Iowa State University. Cooperative Extension Service.
Provides information about soil quality topics including crop rotations, soil amendments, soil health, carbon sequestration and organic agriculture philosophies.
Purdue University. Conservation Technology Information Center.
Reviews soil quality in terms of organic matter and the use of no-till crop production to improve water infiltration.
Cornell University. School of Integrative Plant Science.
"Describes soil constraints and soil quality issues common to soils in New York and the Northeast, provides guidelines on how to conduct in-field qualitative and quantitative soil health assessment and background on Cornell soil health testing, and identifies management strategies for improving soil health based based on the test."