US Soil Taxonomy Structure
The US Soil Taxonomy has an Hierarchical Structure with Four primary levels:
Orders: US Taxonmic Orders distinguish eleven fundamental types of mineral soils and one organic soil. Each Order has a distinct horizon configuration.
Suborders: The Orders are divided into soil 64 Suborders (with over 30 in NZ) primarily on the basis of properties that influence soil formation and/or are important to plant growth.
Great groups: The soil Suborders are divided into Great groups on the basis of similarities in horizons present, soil moisture or temperature regimes, or other significant soil properties. Great groups provide more detail about the range of soils included in each soil Suborder. There are over 500 Great groups.
Subgroup: The soil Great groups are divided into Subgroups, which provide more detail about the range of soils included in each soil Great group. There are over 2500 Subgroups.
Family: Families are established within a subgroup on the basis of physical and chemical properties along with other characteristics that affect management.
Series: The series consists of soils within a family that have horizons similar in color, texture, structure, reaction, consistence, mineral and chemical composition, and arrangement in the profile.