| New Soil Order classification | ALLOPHANIC
Occur in soils with a strong link to allophane clay - usually volcanic in origin. |
| Old Soil Group classification | Yellow brown loams, some red and brown loams and upland yellow brown earths. | |
| Common names associated with this Soil Order | Patoka, Takapau, Kopua, Dannevirke. |
| Physical characteristics | - Occur in volcanic ash, where weathering has provided a high level of allophane clay.
- Dominated by allophane clay, which causes high to very high P retention.
- Erosion is minimal unless it is disturbed, then severe wind and sheet erosion will occur.
- Low natural fertility.
- Low bulk density, therefore resist compaction, less than 0.8T/m3.
- Fine sandy loam with a strongly developed nutty structure.
- Can be deficient in cobalt, magnesium, or potassium. Respond to lime.
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| Drainage and moisture availability | - Well drained, very high macroporosity allowing for rapid water through-flow (permeability).
- High moisture retention, allowing reasonable available water content of 15-25% of soil volume.
- A well aerated soil.
- Layers can become compacted and drainage may be impeded.
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| Rooting depth | - Excellent, soils are consistently deeper than 60cm. Allows trees to tap the nutrient reserves and moisture zones.
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Beautiful, deep topsoil on loess, Patoka Soil
Source: Simon Stokes