Oxidic Soils

The first grape vines in New Zealand were probably planted on these soils by an associate of Samuel Marsden at Kerikeri in 1817

Oxidic Soils are clayey soils that have formed as a result of weathering over extensive periods of time in volcanic ash or dark volcanic rock. Despite high clay contents the soils are friable, with low plasticity and fine structure. They contain appreciable amounts of iron and aluminium oxides.

Oxidic Soil. zoom icon

Occurrence

Oxidic Soils are only known in the Auckland and Northland regions. Parent materials are derived from strongly weathered andesite, dolerite or basalt rock or ash. They cover < 1% of New Zealand.

Physical properties

Soils have limited rooting depth, well-developed and relatively stable structure, slow permeability, and moderate or rapid infiltration rates. Clay contents are high, ranging from 50 to 90%. Soil water deficits are common in summer.

Chemical properties

Oxidic soils are strongly weathered with low reserves of potassium, magnesium, calcium and phosphorus. Clays have low cation exchange capacity at the natural pH of the soil, and phosphate retention is high.

View map of Oxidic Soils

Soil groups

Soil orders are divided into soil groups based on variation in factors such as drainage status, parent material, chemical and physical properties:

  • [XP] Perch-gley Oxidic Soils — periodic wetness caused by a perched water table
  • [XN] Nodular Oxidic Soils — prominent accumulations of iron oxide
  • [XO] Orthic Oxidic Soils — other Oxidic Soils

Distribution maps

Distribution of Perch-Gley Oxidic Soil
Distribution of Nodular Oxidic Soil
Distribution of Orthic Oxidic Soil

Find related content

Soil classification NZSC
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