Bases for Soil Classification in Soil TaxonomyThe physical, chemical and mineralogical, and biological properties of soils as they are today, are the basis for classifying soils in the Soil Taxonomy.
E.g. moisture, temperature, color, texture, structure, organic matter, pH, % base saturation, soil depth, etc. are important criteria for classification.
Some of these properties are observed in the field, but others require precise measurements in the lab.
These precise measurements are used to define certain diagnostic soil horizons, the presence or absence of which determine the place of a soil in the classification system.