Pallic Soils [P]
A cubic metre of some subsoils can weigh more than 1.8 tonnes
Pallic Soils have pale coloured subsoils, due to low contents of iron oxides. The soils have weak structure and high density in subsurface horizons. Pallic Soils are dry in summer and wet in winter
Pallic Soils occur predominantly in the seasonally dry eastern part of the North and South Islands, and in the Manawatu. Parent materials are commonly loess derived from schist or greywacke. They cover 12% of New Zealand.
Soils have slow permeability with limited rooting depth, and medium to high bulk density. They are susceptible to erosion because of high potential for slaking and dispersion.
Soils have medium to high nutrient content ( except for sulphur), high base saturation, low concentrations of secondary oxides, and low organic matter contents.
Soils are strongly worm-mixed, at the boundary of the A and B horizons.
Soil orders are divided into soil groups based on variation in factors such as drainage status, parent material, chemical and physical properties:
- [PP] Perch-Gley Pallic — periodic wetness caused by a perched water table
- [PU] Duric Pallic — Silica-cemented pan in the subsoil
- [PX] Fragic Pallic — a compact pan in the subsoil
- [PL] Laminar Pallic — clay accumulation as thin subsoil bands
- [PJ] Argillic Pallic — clay accumulation as thin coatings on peds or in pores
- [PI] Immature Pallic — weakly expressed Pallic soil features