HBRC > What We Do > Land > Soils of Hawke's Bay

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.
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.
Rooting depth	Excellent, soils are consistently deeper than 60cm. Allows trees to tap the nutrient reserves and moisture zones.

Beautiful, deep topsoil on loess, Patoka Soil
Source: Simon Stokes

Allophanic