Soil Orders

Question 1

Pallic Soils

Answer 1

Pale coloured subsoils, due to low contents of iron oxides. The soils have weak structure and frequently high density in subsurface horizons. Pallic Soils are dry in summer and wet in winter.

Occurrence : 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.

12% of New Zealand.

Question 2

Brown Soils

Answer 2

have a brown or yellow-brown subsoil below a dark grey- brown topsoil. The brown colour is caused by thin coatings of iron oxides weathered from the parent material.

Occurrence : Brown Soils occur in places where summer drought is uncommon and which are not waterlogged in winter. Our most extensive soils covering 43% of New Zealand.

Question 3

Podzol soils

Answer 3

Strongly acid soils that usually have a bleached horizon immediately beneath the topsoil. This horizon is the source of aluminium and iron oxides that have accumulated, in association with organic matter, in an underlying dark or reddish coloured horizon.

Occurrence : Podzol Soils occur in areas of high rainfall and are usually associated with forest trees with an acid litter. The soils occur mainly in materials from silica-rich rocks.

13% of New Zealand.

Question 4

Allophanic Soils

Answer 4

Dominated by the mineral allophane which imparts unique properties. The stiff, jelly-like minerals coat the sand and silt grains and maintain porous, low density structure with weak strength. The soils are identified by a distinctly greasy feel when moistened and rubbed firmly between the fingers. The soil is easy to dig and samples crumble easily when crushed in the hand.

Occurrence : These soils occur predominantly in the North Island volcanic ash, and in the weathering products of other volcanic rocks. They also occur in the weathering products of greywacke and schist in the South Island high country.

5% of New Zealand

Question 5

Recent Soils

Answer 5

Weakly developed, showing limited signs of soil-forming processes. A distinct topsoil is present but a B horizon is either absent or only weakly expressed.

Occurrence: Throughout New Zealand on young land surfaces, including alluvial floodplains, unstable steep slopes, and slopes mantled by young volcanic ash. Their age varies depending on the environment and soil materials, but most are less than 1000 to 2000 years old.

6% of New Zealand