This monograph covers the criteria that need to be used for evaluating soil quality including differences in emphasis from east to west of the country. It covers both mineral and organic soils, both extremely sensitive to mistreatment in their own ways. A proposed classification scheme is presented as a rather important component for ordering our knowledge. The special role of organic matter in soils is discussed from basic principles and description of basic components through to the various effects on the practical attributes of soils use for agriculture.