Illinois Soil Testing Association (ISTA) P.O. Box 42 , Charleston , 61920 About Solutions industries services Home Companies Illinois Soil Testing Association ... Locations Illinois Soil Testing Association (ISTA) Show or hide locations in map Headquarters Office locations Locations served Distributors Manufacturer Illinois Soil Testing Association (ISTA) Headquarters P.O. Box 42 Charleston Illinois 61920 Phone/Fax Number