New Zealand Soil Classification (NZSC)

Classification key for soil orders

To find the correct soil class for a soil we examine the soil horizons (or layers) exposed in the side of a freshly dug soil pit, usually to the depth of about 1 m (unless rock is found at a shallower depth). We then assign the soil to the correct soil class, by using the keys to orders, groups, and subgroups in Hewitt (2010) and family and sibling criteria in Webb and Lilburne (2011). The simplified key below provides a guide to the correct soil order. The keys for assigning a soil to the correct soil class use diagnostic horizons and other defined soil features.

Soils dominated by organic material Organic Soils
Grey colours due to reduction of iron caused by waterlogging beneath a high water table Gley Soils
Soils disturbed by people (made by stripping or mixing the original soil material to depth or by addition of fill) Anthropic Soils

Minimal soil development

Soils on young land surfaces where rock material or sediments in which the soil is formed are fresh and little altered
No topsoil or minimal topsoil Raw Soils
With a distinct topsoil Recent Soils

Intermediate soil development

Soils where the rock material or sediments in which they are formed are altered but still recognisable, with a large proportion of unaltered minerals. The soils have well-developed subsoil horizons if not on shallow rock
Dominated by allophane (from volcanic parent materials, weathered sandstone or derivatives) Allophanic Soils
Dominated by pumice or sandy glassy tephra Pumice Soils
Dominated by high calcium or magnesium from lime-rich rocks or dark basic igneous rocks Melanic Soils
Light coloured rocks or sediments - Semi-arid climate, rainfall less than about 500 mm/year Semiarid Soils
- Subhumid climate with seasonal drought Pallic Soils
- Humid climate, rarely dry except if sandy or stony where they may be drier Brown Soils
- Super-humid climate Podzol Soils

Strong soil development

Soils on old land surfaces where the rock material or sediments in which the soil is formed are mostly transformed to clay
Mainly sedimentary rocks Ultic Soils
Mainly volcanic rocks - Well-developed polyhedral structure Granular Soils
- Dominated by iron and aluminium oxides Oxidic Soils