Most people are familiar with the Linnean classification system used to identify living things. We use scientific names to describe and categorise living things precisely. For example, New Zealand has several subspecies of robins. By using the scientific name Petroica australis longipes, we know that this bird is the North Island robin or toutouwai in Māori.
New Zealand soils also have special naming systems. The various soils have a scientific name, a common name and, in some cases, a Māori name.
New Zealand Soil Classification System
Soil scientists use the New Zealand Soil Classification System to identify specific soils. Soils are classified according to their physical, chemical and morphological characteristics (which refer to the soils’ appearance). Like the Linnean system for living things, soil classification also has a hierarchy. This level of detail allows for accurate communication among scientists.
All soil classification begins with a soil order. Soil orders are subdivided into soil groups, and these groups are divided even further into subgroups. For example, one soil order is Gley. Gley soils drain quite slowly after rain and are strongly affected by waterlogging. They occur throughout New Zealand in low-lying parts of the landscape. The Gley soil order has six soil groups – one of which is Orthic Gley. The Orthic Gley group has eight subgroups. This level of detail is often important to landowners to help them manage their land for optimal production.
The New Zealand Soil Classification System has a fourth category – soil family – which uses parent material, particle size and permeability to further identify and classify the soil.
Common New Zealand soil names
New Zealand soils also have common names. The name usually has the location in which the soil was first discovered and describes the soil’s texture – Pakipaki silt loam, Taupō sand and Waikare clay are just a few examples. Scientists and farmers often use the common soil names because they are meaningful to a particular location. A dark greyish-brown silt loam found in the Waikato has the scientific classification Typic Orthic Gley, but locals are more likely to refer to its common name – Te Kōwhai silt loam.
Māori soil names
The Māori word for soil is oneone. Before Europeans arrived in New Zealand, Māori had already identified at least 30 types of soil.
There are general soil names such as keretū (clay), parakiwai (silt), kenepuru (silt), onetai (sandy soil), oneparaumu (very dark fertile soil) and onenui (a rich soil made of clay, sand and decayed organic matter). Māori also classified soils by more specific characteristics. Keretū (clay) is broken up into several categories: kerewhenua (yellow clay), kerematua (stiff clay), kōtore (white clay), taioma (pipe clay), matapaia (baked hard and used as a stone for cooking) and uku (soft white or bluish clay).
Just as the current common soil names are associated with a particular location, Māori place names may indicate the local soil type. For example, Kereone (in the Waikato) has sandy silt, and Onetea (in the Far North) has a light sandy soil.
Nature of science
Throughout history, humans have developed detailed knowledge of how soils differ from one another and used their local languages to name or describe these soils. These names and descriptions are meaningful on a local level, but scientific classification allows scientists to discuss soil characteristics on a global basis.