Soil in New Zealand

by Dr J Floor Anthoni (2000)
New Zealand is a very young country with few inhabitants. Only since 1910 did it have over one million people, and today just less than 4 million. Although it does not have the pressures of overpopulation, it nonetheless suffers the ill effects of it. NZ farm produce provides over half the value of exports, contributing largely to the people's standard of living. Its economy is based largely on the energy from the soil, thus being sustainable in principle. But erosion of the land and nutrient runoff from livestock farming is its main problem.

About New Zealand, its history relating to agriculture and its dependence on agricultural exports.
New Zealand's tectonic drift over 200 million years, geology, climate, soils and land cover.
New Zealand's most fertile soils were once covered in native forests of slow growing podocarp trees. Deep subsoils with shallow topsoils formed, which are susceptible to erosion.
The Minister for the Environment has made a strategy for sustainable land management, which consists of forming local care groups, education and voluntary action. Farmers are adopting a voluntary code of practice for handling and applying fertilisers. But will it help?
don't miss out reading why NZ is so special due to its location, currents and economy (12 pages)

The publications listed in blue are available from the Seafriends Library.
MfE: Sustainable land management, a strategy for New Zealand. June 1996; ME 201.
MAF: Agriculture and forestry in New Zealand - an overview
MAF: Control of soil erosion on farmland. by D L Hicks. MAF Policy Technical Paper 95/4. Aug 1995.
MAF: New Zealand Agriculture. 1974. 
FertResearch: Code of Practice for fertiliser use. 1998.
Federated Farmers of NZ: Sustainable agriculture manual. 1994.
Molloy, Les: The living mantle: soils in the New Zealand landscape. 1988, 1998.
Statistics NZ: The NZ official yearbook 1997 (100th edition) and 2000 (centennial edition)
MfE: Ministry for the environment looks at broader issues such as water quality and global warming and administers the Resource Management Act (RMA).
MAF: Ministry of Agriculture and Forestry (MAF) creates opportunity for, and manages risk to, New Zealand's food, fibre, forestry and associated industries. 
Agresearch: the life sciences link between the past of pioneering and the better future where our products will improve the quality of life and the environment around the world in a responsible and sustainable way. Science education section.
Landcare Research: Landcare Research is an independent Crown Research Institute which focuses on management of land resources for conservation and for primary production. Science section. SINDI Soil Indicator assessment tool. Soil Quality section.
HortResearch: New Zealand's largest horticulture and food research organisation.
Hort-net: an information centre for NZ's plant-based industries.
FertResearch: NZ Fertiliser Manufacturers' Research Association. Links to agricultural resources.
Crop and Food Research:  provides quality research, technologies and services for arable foods, vegetable foods, seafood, ornamentals, animal feed, plant products and forestry.
Forest Research: New Zealand Forest Research Institute Limited 
GNS: Institute of Geological & Nuclear Sciences; earth and nuclear scientific research (IGNIS).
ESR: Institute of Environmental Science and Research.
MED: Minister for Economic Development and its section on NZ minerals.
NZ treasury: the Government's lead adviser on economic and financial policy. Our work is aimed at helping governments achieve higher living standards for New Zealanders.
NZ Statistics: Statistics New Zealand is the national statistical office.
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Comparing NZ with the rest of the worldNew Zealand is a young country, only just over 150 years old. In 1840, its founding document, the Treaty of Waitangi, was signed by representatives of Maori tribes and the Queen. At that time, about 2000 white men (pakeha) lived in NZ, but its population rose steadily to reach 3.8 million in 1999 (2 million in 1950). With a surface area of 26.7 million hectares, each New Zealander has 7.0 ha as living space (USA= 940Mha/290M= 3.2 ha each; Holland= 0.2). But only 3.2 ha of productive land is available for every person. With a coastline of 15,000 km, each inhabitant has 3.95 m, while never living further than 130 km away from the sea.

This map shows NZ's latitudinal position relative to other places in the world. Located in the temperate climate zone, NZ has a sea climate with moderate to high rainfall and few weather extremes. It is one of the few places on Earth where rain falls in all seasons. Orientated in a north-south direction between latitudes 34ºS and 47ºS, the two main islands experience a temperature gradient of about 7 degrees, which is also the average difference between summer and winter. NZ has a climate conducive to farming. See also Oceanography/Why NZ is so special.
Farming in NZ was spurred by the needs of a fixed overseas market of 40 million people: Great Britain. NZ almost became an extension of the British economy, 'Britain's offshore farm'. With a per capita Gross Domestic Product (GDP) only exceeded by Switzerland, NZ enjoyed high prosperity until the early 1970s. But England's entry into the European Economic Community, closed that market and NZ had to find other destinations for its farming produce. The changeover depressed incomes and exposed the nation to the fluctuations of world markets, perhaps like no other nation, for the world grows far more food locally, than is traded internationally. It would be fair to say that world trade consists mainly of excess food in good years, which depresses demand and with it, prices. It suggests that the world has enough meat, hides and butter. Successive governments have encouraged other sectors of the economy to develop, often to the detriment of the agricultural base. NZ's recent globalisation since 1984, removed farm subsidies and has driven many exporters overseas or to wind up, resulting in a worrying current account deficit of 30-40% of export income, and rising steeply. The past 15 years has seen an economic growth based on foreign investment to the tune of NZ$ 100M, or 110% of GDP, requiring interest and dividend payments exceeding NZ$ 7700M. GDP per capita is now close to the lowest of the developed countries. NZ cattle and sheep numbers declined by 24%.
New Zealand exports in millions of dollars.
Commodity 1998 1999
Milk powder, butter and cheese
Meat and edible offal
Casein and caseinates
Raw hides, skins, leather
Fruit and nuts
Paper and paperboard
Wood and wood articles
Fish, crustaceans and molluscs
Mechanical machinery
Aluminium and articles thereof 
Electrical machinery
Iron and steel and articles
Mineral fuels
Textiles and textile articles 
Other commodities
3 729
2 928
1 557
1 027
5 365
4 005
2 830
1 408
1 158
1 045
5 480
All merchandise exports 22 021 22 554
 Solar-economy products 1998:  12 728 M$ (58%), 1999: 12 920 M$ (57%). The agricultural industry employs only 11.4% of the workforce.

Since 1984, NZ has unilaterally removed its support to farmers. Government assistance to farmers is very low by international standards. NZ farmers have the OECD's lowest producer support rates. The producer support rate in Australia is 3x greater, in the USA 5x, and many times greater in the EU, Norway, Switzerland and Japan.
In order for a dairy farmer to remain economic, he must milk over 230 cows twice daily. A sheep farmer has 2000-3000 sheep. A beef farmer has over 500 steers.

Nothing can change the fact that NZ remains eminently suitable for producing exports from solar inputs. As the table above shows, over half of its export income comes from agriculture and fisheries, a sound sustainable base which earns little in a world awash with food, but perhaps more in the future world of scarcity.
The diagram below gives a breakdown of NZ's agricultural base today, compared with 30 years ago. Dairy production increased while that of sheep and cattle decreased. NZ has about 45 million sheep and 8 million cattle (of which 4.6M beef cattle).

New Zealand's natural advantages are:

New Zealand's natural disadvantages are:
Once wholly covered in forest and scrubland, present-day land cover reflects the intensity with which NZ has been developed, leaving only 33% of its original vegetation intact (red colour in the table). Although the tussock lands still have their original land cover, they are grazed heavily, causing ecological problems.
Taking advantage of the rich, deep forest soils, the steep hill country has been deforested, but after less than a century of farming, these soils have lost their productivity and grass cover, causing serious erosion. Fortunately many of these degraded soils can be salvaged by planting forests of radiata pine (Pinus radiata, originating from California).
degraded and reforested land
The photo shows badly degraded and bared grassland soils, causing worrisome erosion. In the background a young plantation of highly productive Pinus radiata pine trees.
New Zealand's land cover, in km2 (x100 ha)
Type of land cover North I South I NZ km2 %
indigenous forest
inland wetland
coastal wetland
planted forest
inland water
bare ground
coastal sands
mines and dumps
urban areas
urban open space
Total 114,615 152,357 266,972 99.9
Source: MAF Land Cover Database Statistics, 1997.
This table shows how the land is used in New Zealand. Barely 33% of the original vegetation still exists, although often the best trees have been logged from the native forests. By far, the largest area (52%) is covered in the native mountain tussock grass and introduced grasses. Only 5% is considered high quality soil, being both fertile and flat, while also enjoying enough rainfall. 62% of the land is occupied; 81% of this is used for pastoral agriculture.

In 1991 New Zealand introduced the Resource Management Act (RMA) and created a new Ministry for the Environment to administer it. The RMA is about using resources in a way that provides for the social, economic and cultural wellbeing of people, while safeguarding the environment for ourselves and future generations. Local government (regional and local bodies) are responsible for making it work. The RMA requires many activities to be sustainable, to obtain a Resource Consent and to produce an Environmental Impact Assessment, often leading to excessive bureaucracy. The MfE produces sustainable strategies for every resource type, and local bodies produce plans for making it work. The RMA has seriously started NZ on the road to a sustainable society even though many have doubts.
trends in agricultureThe history of agriculture in NZ is best illustrated by the four graphs in the diagram. The black curve shows NZ population steadily climbing, accelerating slightly after World War II. Sheep numbers and cattle (not shown) kept pace, almost at the same rates of growth. Since NZ's welfare depends mainly on agricultural exports, the number of sheep per person has always been a critical measure of it. However, since 1986 when the subsidy on fertilisers was abolished, the number of sheep have declined drastically, from a high of 70 million to 49 million in 1995 and 45 million in 1999. Over the same period, nearly 5 Mha (25%) out of a total 21.25 Mha in 1981, has been taken out of production. It corresponds roughly to the expected degradation of around 30% over 15 years, by not applying fertilisers. The red curve of total fertiliser use, shows a drop of nearly 50%. Considering that the more prosperous dairy farms were not affected, most of the effect of reduced fertiliser application was felt by the hill country, which is most prone to erosion.

The green curve shows the number of hectare planted in forest, during the century. In the Great Depression years (1925-1935), the Government planted large areas of pumice soils (the Kaingaroa Forest) in pine forests, which provided the timber for sawmilling, pulp and paper forty years later. Between 1965 and 1985, when the state forests came on stream, it was clear that forestry was a viable business in NZ, inviting both Government and private plantings. After 1984 when tax rebates were phased out, new plantings declined sharply, and Government plantings dropped to zero because all cutting rights had been sold to private interests. Very recently, forest plantings have reached new heights in anticipation of higher prices and a high demand by the paper industry. Also many farmers are now retiring their degraded lands and planting these in pine forests (14,000 forests of less than 100 ha). In 1995, 5.3 million cubic metre of timber was milled for sawlogs, against 4.1 for pulp & paper and 4.8 for export. Total domestic processing was 11.1 million cum in 1996.



NZ continental driftAbout 200 million years ago (200Mya), Gondwanaland started to break up, allowing the continents to drift towards their present positions. New Zealand was part of the Rangitata land mass, adjacent to Australia and Antarctica. Most of the sedimental rock came from eroding Antarctica. 
By 110 Mya, India, Africa and South America were well separated from Antarctica. By 80 Mya, the Rangitata 'continent' which included New Caledonia at its northernmost tip, started to peel off. In the meantime it had drifted some 90 degrees around the South Pole, but now it was heading in a northerly direction. The southern floe of Rangitata broke and started to rotate counter-clockwise, pushing what is now the South Island, along the Alpine Fault onto the North Island, while continuing its rotation. 

This 'Alpine Fault' which runs the length of the South Island, is also the boundary between the Indo-Australian (north) and the Pacific (south) ocean plates. Along their boundaries runs the Hjort Trench, the Puysegur Trench, flanked by the Macquarie Ridge, south of NZ , and the Hikurangi Trench and Kermadec Trench, flanked by the Kermadec Ridge, to the north of NZ.
NZ geologyAs the South Pacific plate slid against the Indo-Australian plate, it pushed up the Southern Alps, deforming the rocks, which matamorphosed to schists (grey colour). The oldest rock (granite) is found in the South Island, dating back to the late Cretaceous (70 Mya, million years ago). The metamorphic rocks (greywacke) that pushed up the Southern Alps, consist of Antarctic sediment dating back to when NZ was still connected to it. 

The NE part of the South Island is still shifting SE-wards along the (red) alpine fault. At some stage in the Tertiary period (20 Mya), it pushed up an island arc of volcanoes (dark brown). Volcanoes of that age are also found in the northern tip of the North Island. Later volcanic activity moved gradually SE-wards (Little Barrier, Great Barrier, Auckland, Coromandel) and present volcanic activity is found in the central plateau from Lake Taupo to White Island (dotted red line). The old sedimentary rocks are hard greywacke. On top of these base rocks, alluvium was deposited and soils formed according to local climate and vegetation.
NZ rainfallMoisture from rainfall is an important factor in soil formation and agriculture. This rainfall map shows that NZ has a moist climate, with the ideal amount of rain between 1 and 2m (1000-2000mm) annually, but there are some exceptions. All mountain ranges capture more rain (2-3m) and the west coast of the South Island captures up to 8m annually. As we have seen in previous chapters, areas of high rainfall are very difficult to exploit in a sustainable way, but fortunately, most have been left in their original native forest cover (see map below). Around the settlement of Alexandra, back from Dunedin on the South Island, occurs a desert pocket with low rainfall. The prevailing westerlies unload their rains on the West Coast, leaving most of the South Island drier than the North Island.

NZ soilsSoils developed from the bedrock under the influence of climate and vegetation. Clays and loams developed from both sedimentary rocks (yellow-brown, yellow-grey and grey-brown earths) and volcanic rocks (yellow-brown loams and red-brown loams). The red-brown and yellow-brown volcanic loams are the most fertile soils, used for market gardening and intensive dairy farming. They are mainly found in the North Island. The Central Plateau around Lake Taupo is covered in yellow-brown pumice soils. Taupo's most recent eruptions happened 30,000 and 1800 years ago, the latest eruption leaving hardly enough time to form a new soil profile, one reason why this area is not very suitable for farming. The other reason is the lack of trace elements like cobalt, important for animal health.
The South Island is characterised by bare mountain peaks, yellow-brown high country soils covered in tussock, lowland yellow-grey soils for intensive farming and cropping, and pockets of arid grey-brown earths in central Otago.

Current vegetation in NZThe vegetation map shows today's vegetation. The dunes, pasture, high-quality pasture and tussock are all grazed. Native forests remain only on the mountain ranges where farming is impractical. The highest mountains are covered in alpine vegetation or bare rock. Mountain tussock grass is found mainly on the South Island's high country.
This map does not do justice to the many plantation forests, which are scattered all over NZ. The large plantation forests near Lake Taupo were planted in the years of the Great Depression.


NZ forest soilsOn its 60 million journey of isolation, NZ developed a unique flora and with it a fauna consisting mainly of birds, and soils resulting from this. The native forests are characterised by very slow growing trees (podocarp) which keep their foliage in winter. Podocarps are an evolutionary invention in between pinetrees and leafy trees. Their wood is also in between softwood (pine) and hardwood (leafy trees). Their slow metabolic rate and dense leaf litter caused soils to erode slowly, resulting in deep subsoils with thin top soils but thick litter layers. 
After milling and burning of the forest, the litter layer disappeared and the thin top soil was farmed for grassland. Grassland has a high metabolic rate, which requires soils and their organisms to adapt. In general, NZ soils are acidic, low in sulphur and phosphate and some trace elements. As can be expected, application of fertiliser boosts their fertility by 50%.

Because of their initial fertility, farmers were wrongly led to believe that steep hill country could be farmed sustainably. Driven by false expectations and often by poverty and the need to survive, farmers turned steep forests into pasture. Half a century later, these soils started eroding badly, requiring them to be reforested as a last resort.

Scientists estimate the loss of soil in New Zealand, through erosion and transport by rivers to the sea at 400 million ton per year. It arises mainly from the 22 million hectare of cultivated land, averaging 18 t/ha or 10 - 20 times the rate of natural soil formation. It is vastly unsustainable.
[see also the principles of degradation for details of NZ soil statistics]

footrot flats cartoon, Murray Ball.

steep country farming
Amazingly steep hill country in the Wanganui catchment, has been turned into pasture, but is now eroding badly. Notice the amount of bare soil visible from this distance. Notice also how well the pine trees are doing, where the grass failed.
dying trees
The vision of rolling carpets of green grass has driven many farmers to eliminate every tree from their properties, even where trees were holding the soil. In this case, the native trees died spontaneously, probably because they could not compete with the faster metabolising grasses.
degrading grassland
Degrading grassland can drive a farmer into a spiral of diminishing returns. Unable to afford the necessary application of fertiliser and lime, while also overgrazing it from necessity, the land gradually loses its productivity.
Conservation planting
View from Pakiri Hill to Leigh, Northland NZ. In 1975 the rolling pasture had hardly any trees, but now in 1998, many trees have been planted to conserve the soil. Notice gully plantings, retired pasture, forests and pasture trees.

grass growth in NZNZ pasture consists of various grasses, dominated by ryegrass, mixed with clovers. Bacteria in the clover's root nodules bind nitrogen from air, providing all the nitrogen needed. Pastures are fertilised with lime (to lower acidity), sulphur and phosphate. Most farmers feed missing trace elements in the form of enriched salt lick blocks (copper, cobalt, selenium).
The climate is kind enough to leave stock outside during winter and summer. The diagram shows the typical cycle in the productivity of a typical NZ farm. Grass growth peaks in spring (Oct/Nov) and once again in autumn (Mar/Apr). Nature times calving and lambing with the spring flush of grass, requiring only 3 months of feed supplements. These are provided in the form of hay or silage, harvested in early summer when grass growth exceeds demand, or by leaving tall grass on some reserved paddocks. Often in remote areas, stock is allowed to graze road sides. Note that grass productivity varies from year to year and month to month, depending on the weather.

Agricultural erosionThe map on the right shows farmed land in NZ, and its susceptibility to erosion. Such susceptibility depends mainly on slope and land use, but to some extent also on the quality of the soil. The black areas on the map are not farmed. As one can see, a vast area is moderately to severely susceptible to erosion. such lands may well need to be reforested, which would reduce livestock far below the levels of today. It is feared that world reforestation efforts for the sake of carbon dioxide emission credits, could depress the price of timber in the foreseeable future.


Towards sustainability

Land use in NZ over the last 150 years has resulted in significant, and sometimes severe, environmental problems. Because NZ depends so much on its agriculture, unsustainable land management has far-reaching effects on our economy and way of life. In 1996 the NZ Government pledged to give priority to developing and implementing a Sustainable Land Management strategy (SLM) for NZ. 

The SLM strategy aims to:

The principles of the strategy are: The SLM strategy is built on the principles of continual improvement, voluntary actions by land managers and making relevant information accessible so changes can take place. The Government has clearly chosen for a gradual voluntary approach, rather than a hierarchical bureaucratic chain of command with the consequential transaction cost. "There is insufficient understanding of the complex interaction of the biophysical and socio-economic systems to justify and implement widespread regulatory measures at this stage.... The strategy does not start from zero. Rather, it is intended that it build on the economic and structural reforms of the last ten years. These include, for example, the removal of subsidies and tariff protection, the Resource Management Act (1991), The Biosecurity Act (1993), and the many local and regional land use initiatives already underway." What all this means, is that nobody has a clue of how to go about it. Read it again, Sam.
Sustainable Land Management structureThe diagram shows the proposed management and reporting structure, originating from the ministers for the Environment and other departments. Since local and regional Government is responsible for administering the Resource Management Act, they are also responsible for implementing the SLM. By stimulating and creating local care groups (land care, harbour care, dune care, river care, etc.), a growing number of people is becoming aware of and involved with SLM. Most communication happens between Regional Councils and the care groups, with information flowing between them, but mostly from the top downward. The SLM Contact Group oversees the development and implementation and reports back to the Ministers. The Regional Council Policy Managers Forum reviews the approaches taken by councils in their preparation of policies and plans under the RMA.
Focus Groups will be convened to address specific policy or technical issues related to SLM. These groups will be task-oriented, have specific terms of reference related to the task, and will be disbanded once the work has been completed.
The Landcare Trust is an organisation facilitating this process. It will train a national network of Landcare and community group facilitators and encourage the establishment of Landcare groups.
The scientific support side stimulates the kinds of research that can be done towards SLM, assisted by a flow of funds. Care groups can be involved in various research projects.

Problem areas that have so far been identified for priority action are:

Monitoring and review will be undertaken to ensure that tangible results are achieved over time:

The Government wishes to use freemarket incentives rather than subsidies, to encourage landowners to manage more sustainably: Reader please note that none of these incentives have proved to work anywhere in the world. New Zealand obviously still has a long way to go to reduce its soil losses by 95%, to match the rate of natural soil formation, but the foundation has been laid for a change towards this end. After nearly a decade, very little if anything at all, has been achieved (2005).

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