aspects of life including providing the substrate for roads and
buildings, recreational fields, filtering of water, recycling of
nutrients and wastes, and preserving archaeological and
historical features. Soils and their associated landscapes
provide the visually outstanding and remarkably variable
landforms throughout the country that inspire New Zealanders and visitors alike.
The soils of New Zealand are diverse, reflecting the wide
range of environmental conditions. The major groupings of
soils (orders) that are identified in global soil classification
systems can all be found in New Zealand. However, like
snowflakes, no two soils are identical and so the study of
soils gives an appreciation of the complexity, as well as the
beauty, of soil.
Humans have impacted on New Zealand soils since the
arrival of Polynesians in about 1280 AD from tropical
eastern Polynesia. The indigenous descendants of those first
settlers, Māori, first cultivated soils using techniques
imported from the Pacific to grow the tropical kumara (sweet
potato), and other crops. The first Polynesian settlers were
confronted with a landscape largely clothed in extensive
forest. About 96% of the North Island and 72% of the South
Island were under forest (*82% forest cover in total). The
early Māori cleared large tracts of forest, using fire, so that
by *1800 AD about half of the South Island and a third of
the North Island forest had been replaced by bracken
fern-land, grassland, and tall scrub.
The arrival of Europeans from the early-mid 1800s
brought considerable changes with further deforestation as
pastoral agriculture was established and new plants and
animals were introduced. The development of exotic grasslands for pasture accelerated from the 1870s when
landowners were required by law to ‘improve’ the land.
Native forest cover today amounts to about one-quarter of
New Zealand. Over the twentieth century, in common with
other parts of the world, there was a greatly increased scale
and rate of change in the New Zealand soil environment due
to rapid changes in technology and marked increase in
population. Key activities, along with pasture establishment,
included use of drainage and fertilisers. About 85% of natural wetlands were drained to develop flat land for highly
productive agriculture. From the late 1940s-early 1950s, the
advent of aerial topdressing of fertiliser helped New Zealand
to greatly increase food production from its soils, which
generally have relatively low natural fertility. Improved
pasture also helped to stem the rate of loss of soils in erosion-prone hill country in the eastern North Island and
elsewhere. The widespread use of fertilisers has led to issues
with water quality in the twenty-first century because of the
increase in nutrients, especially nitrogen and phosphorus, in
the soil-water system. The rate of transformation of the New
Zealand landscape following (relatively recent) human arrival is among the fastest known in the world.
Within this chapter we introduce the environmental factors (called the soil-forming factors)—geology (parent
material), topography, climate, organisms, and time—that
interact to form the diversity of New Zealand’s soils. We
discuss some key attributes of the soil, including study of the
soil profile that represents a soil ‘individual’, provide an
overview of the New Zealand Soil Classification, and
introduce the 15 New Zealand soil orders and their distribution. In following chapters, each soil order is described in
a systematic format that documents its main features, genesis, relationships with landscapes, key properties, classification, and use and management. The book then concludes
with a chapter on soils in the Ross Sea region of Antarctica
and a final chapter that considers New Zealand soils in a
global context, soil formation pathways and soil and land
evaluation. A series of ‘ratings tables’ that define terms such
as ‘low’, ‘medium’, and ‘high’ for a range of soil chemical
and physical properties are included in Appendix A,
Tables A.1 and A.2. The terms in the ratings tables are
followed throughout this book.
1.2 The Environmental (Soil-Forming)
Factors that Influence New Zealand Soil
Development
1.2.1 Geology, Soil Parent Materials,
and Topography of New Zealand
A varied range of geological materials and topographic
features contribute to the diversity of New Zealand soils.
Although New Zealand appears as a series of islands,
geologists have come to recognise the land mass of New
Zealand as the emergent part of a recently identified eighth
continent, named Zealandia, most (94%) of which is currently beneath the sea (Fig. 1.1). New Zealand lies on the
collisional plate boundary between the Pacific and Australian tectonic plates which are moving obliquely towards
each other at a rate of about 40 mm/year. In the North Island
the Pacific Plate is being subducted beneath the Australian
plate resulting in current volcanic activity in the Taupo
Volcanic Zone in central North Island and the Taranaki
region (with the Auckland Volcanic Field also regarded as
active). To the south of the South Island the subduction is in
the opposite direction with the Australian Plate being subducted beneath the Pacific Plate.
Through the central part of New Zealand the boundary of
the two plates is marked by the Alpine Fault, a transform or
strike-slip fault which passes mainly along the western
margin of the Southern Alps, splitting into a number of
sub-faults in the northern South Island that continue
north-eastwards through, and east of, North Island. There
has been substantial uplift of sediments on the Pacific Plate,
2
1 Introduction
buildings, recreational fields, filtering of water, recycling of
nutrients and wastes, and preserving archaeological and
historical features. Soils and their associated landscapes
provide the visually outstanding and remarkably variable
landforms throughout the country that inspire New Zealanders and visitors alike.
The soils of New Zealand are diverse, reflecting the wide
range of environmental conditions. The major groupings of
soils (orders) that are identified in global soil classification
systems can all be found in New Zealand. However, like
snowflakes, no two soils are identical and so the study of
soils gives an appreciation of the complexity, as well as the
beauty, of soil.
Humans have impacted on New Zealand soils since the
arrival of Polynesians in about 1280 AD from tropical
eastern Polynesia. The indigenous descendants of those first
settlers, Māori, first cultivated soils using techniques
imported from the Pacific to grow the tropical kumara (sweet
potato), and other crops. The first Polynesian settlers were
confronted with a landscape largely clothed in extensive
forest. About 96% of the North Island and 72% of the South
Island were under forest (*82% forest cover in total). The
early Māori cleared large tracts of forest, using fire, so that
by *1800 AD about half of the South Island and a third of
the North Island forest had been replaced by bracken
fern-land, grassland, and tall scrub.
The arrival of Europeans from the early-mid 1800s
brought considerable changes with further deforestation as
pastoral agriculture was established and new plants and
animals were introduced. The development of exotic grasslands for pasture accelerated from the 1870s when
landowners were required by law to ‘improve’ the land.
Native forest cover today amounts to about one-quarter of
New Zealand. Over the twentieth century, in common with
other parts of the world, there was a greatly increased scale
and rate of change in the New Zealand soil environment due
to rapid changes in technology and marked increase in
population. Key activities, along with pasture establishment,
included use of drainage and fertilisers. About 85% of natural wetlands were drained to develop flat land for highly
productive agriculture. From the late 1940s-early 1950s, the
advent of aerial topdressing of fertiliser helped New Zealand
to greatly increase food production from its soils, which
generally have relatively low natural fertility. Improved
pasture also helped to stem the rate of loss of soils in erosion-prone hill country in the eastern North Island and
elsewhere. The widespread use of fertilisers has led to issues
with water quality in the twenty-first century because of the
increase in nutrients, especially nitrogen and phosphorus, in
the soil-water system. The rate of transformation of the New
Zealand landscape following (relatively recent) human arrival is among the fastest known in the world.
Within this chapter we introduce the environmental factors (called the soil-forming factors)—geology (parent
material), topography, climate, organisms, and time—that
interact to form the diversity of New Zealand’s soils. We
discuss some key attributes of the soil, including study of the
soil profile that represents a soil ‘individual’, provide an
overview of the New Zealand Soil Classification, and
introduce the 15 New Zealand soil orders and their distribution. In following chapters, each soil order is described in
a systematic format that documents its main features, genesis, relationships with landscapes, key properties, classification, and use and management. The book then concludes
with a chapter on soils in the Ross Sea region of Antarctica
and a final chapter that considers New Zealand soils in a
global context, soil formation pathways and soil and land
evaluation. A series of ‘ratings tables’ that define terms such
as ‘low’, ‘medium’, and ‘high’ for a range of soil chemical
and physical properties are included in Appendix A,
Tables A.1 and A.2. The terms in the ratings tables are
followed throughout this book.
1.2 The Environmental (Soil-Forming)
Factors that Influence New Zealand Soil
Development
1.2.1 Geology, Soil Parent Materials,
and Topography of New Zealand
A varied range of geological materials and topographic
features contribute to the diversity of New Zealand soils.
Although New Zealand appears as a series of islands,
geologists have come to recognise the land mass of New
Zealand as the emergent part of a recently identified eighth
continent, named Zealandia, most (94%) of which is currently beneath the sea (Fig. 1.1). New Zealand lies on the
collisional plate boundary between the Pacific and Australian tectonic plates which are moving obliquely towards
each other at a rate of about 40 mm/year. In the North Island
the Pacific Plate is being subducted beneath the Australian
plate resulting in current volcanic activity in the Taupo
Volcanic Zone in central North Island and the Taranaki
region (with the Auckland Volcanic Field also regarded as
active). To the south of the South Island the subduction is in
the opposite direction with the Australian Plate being subducted beneath the Pacific Plate.
Through the central part of New Zealand the boundary of
the two plates is marked by the Alpine Fault, a transform or
strike-slip fault which passes mainly along the western
margin of the Southern Alps, splitting into a number of
sub-faults in the northern South Island that continue
north-eastwards through, and east of, North Island. There
has been substantial uplift of sediments on the Pacific Plate,
2
1 Introduction