Pallic Soils

Abstract

Pallic Soils are prominent on the rolling downlands of the lower North Island and eastern South Island. Pallic Soils, the third-most extensive soil order, covering 12% of New Zealand, occur in regions where there is normally a dry summer with a mean annual rainfall of about 500–1000 mm in the South Island and <~800 mm in the North Island. Pallic Soils are often formed in loess, a uniform silt-dominated material that is blown off river floodplains and deposited onto the surrounding landscape. A dense (soil dry bulk density ≥~1.5 t m⁻³) fragipan often forms in the subsoil which can obstruct root penetration and drainage. Thus Pallic Soils often suffer winter wetness, as water perches above the fragipan, and are also prone to summer drought. Subsoils are pale-coloured (“pallic”) because of their low contents of iron oxides and, in some cases, gleying. Pallic Soils are most suitable for pastoral grazing, maize, and other summer crops. Tree crops may be limited by winter saturation and rooting depth. Subsoil drainage can be effective in preventing winter or spring saturation. Some Pallic Soils form in alluvium or slope debris and are friable, without a strong fragipan, hence are deep rooting and versatile.

In regions with a summer drought

the Pallic Soils are about

with dense subsoils formed in loess

the winter wet may make one curse.