Soiltest is the Northwest's only STA approved compost testing laboratory. We do DOT compost testing as well. See our new price list and request form on our website.
USDA Practice Standard 590 for Washington State has been updated. Testing done to comply with manure management plans as part of USDA Farm Bill Programs will be required to use a laboratory that is successfully meeting the performance standards of the North American Proficiency Testing-Performance Assessment Program (NAPT-PAP). The Phosphorus Index calculations can be made from only Bray-P (western Washington) and Olsen-P (eastern Washington).