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 |
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| 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 |
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| 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 |
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| 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 |
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