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System Title

5.15 New Zealand Genetic Soil Classification
Keywords Soils; classification; soil maps
Description The New Zealand Genetic Soil Classification developed because of the need for reconnaissance mapping of New Zealand's soils. This system recognised " soil groups" and related them to the environmental factors that most influenced their character. Knowledge of these relationships helped the prediction of soil classes from observations of geology, landscape, climate and vegetation. Such predictions allowed rapid progress in the broad scale exploratory mapping of New Zealand soils.

The higher levels of this hierarchical classification are subdivided as follows:

  • Category 1 -this is built on 11 basal forms of the soil body that were recognised in the early stages of soil surveys. These classes cut across latitudinal and altitudinal climatic zones.
  • Category II -this divided the basal forms by recognising the main energy status of the soil as indicated approximately by latitudinal and altitudinal zones and by soil moisture.
  • Category III -this subdivides the classes in category II. Those classes that contained mineral soils with strongly developed horizons were subdivided according to the state of weathering of the soil body as indicated by the kind and grade of argillisation. The other classes were subdivided according to the processes of accumulation, removal and mixing. These processes tend to oppose progressive development of a weathered soil body and the formation of horizons.

There are both common and technical names for classes in categories I, II and III.

The lower categories were subdivided according to processes and properties of genetic significance that modify the principal classes as follows:

  • Category IV -the fourth category was subdivided into broad classes based on key remaining morphological differences. These were interpreted in terms of the type and degree of processes that produced them. These processes were in two groups: those that led to, and those that tended to retard, the development of ordinary soil horizons. Examples of the first group include illimerisation, podzolisation and gleying. Examples of the second group of processes are erosion, accumulation and mixing.
  • Category V -in this category subdivision was based on the state of enleaching which is the balance of the incoming and outgoing mineral ions in the active fraction of the soil body.
  • Category VI -this category was subdivided according to the remaining combinations of soil properties due directly or indirectly to differences in parent material;
  • Category VII -this category was subdivided according to texture, the organic profile and to modifications that affect the soil profile partially but not strongly enough to be expressed in higher categories.

Names of the classes in these categories are descriptive and are derived by modifying the name of the principal class by the appropriate adjectives or adjectival phrases.

The genetic names for soils emerge from the criteria applied under the various categories. The complete names are generally long. Simpler names can be derived by omitting characteristics that are weakly expressed and redundant terms.

To assist with understanding soil relationships the genetic classification of soils is often arranged in a Zonal pattern. This is not a necessary part of the classification. It is just a special arrangement of the classes in category III. Soils that directly reflect climate and vegetation were called zonal soils. Other soils were regarded as dominantly intrazoanal or azonal soils.
Original Purpose. The system was developed for the broad scale mapping of New Zealand soils. It related soils to environmental factors that most influenced their character. This allowed soil classes to be predicted based on observations of geology, landscape, climate and vegetation. These predictions allowed rapid progress with the broad scale exploratory mapping of New Zealand soils.
Status This system was initially developed during the 1940s (Taylor, 1948) and was refined during the next 20 years (Taylor and Cox, 1956; Taylor and Pohlen, 1962). The system was used extensively by researchers and land managers. Since the late 1980s the system has been superseded and replaced by the New Zealand Soil Classification as the classification of preference for researchers.
Organisation Manaaki Whenua -Landcare Research
Jurisdiction New Zealand
Contact person/position Alan Hewitt
Scientist
Address Manaaki Whenua - Landcare Research
Private Bag 1930
Dunedin
Phone +64 3 477 4050
Fax +64 3 477 5232
Email hewitta@landcare.cri.nz
Available format Publications
Access Freely available
Geographical coverage New Zealand  

 

Operational Specifications

  
Scale of Operation Wide range of scales from 1:5,000,000 to detailed site maps.
GIS Compatibility This would require accurate locational data that would allow polygon boundaries to be clearly defined.
Relationship between levels in the classification system There is a hierarchical relationship between the categories in the classification system.
Contributing databases/ classification systems N/A
Contributing database GIS compatibility N/A
Relationship with other classification systems and spatial frameworks. This system has been superseded by the New Zealand Soil Classification for scientific research purposes.
Relationship with other databases Many soil maps have been compiled using this classification system.

 

Current and emerging use for:

  
Assisting with determining historic state/ baseline This soil classification can assist with a determination of historic state.
Assisting with determining current state/ baseline The soil classification can describe the current state of the soil, especially when the full classification is used.
Asssisting with scenario building and modelling of possible futures N/A
Risk Assesment The soil classification should be able to identify sites of high risk for particular activities.
Monitoring site selection and sample design The soil classification could be used for site selection for monitoring purposes.
Aggregating and reporting data locally, regionally and/or nationally It is possible to aggregate data up the levels in the hierarchy although the classification is usually used top-down. Data reporting can be at local, regional or national levels.

Current use (who,level,why)

The New Zealand Genetic Soil Classification system has been extensively used for mapping the soils of New Zealand. While this system has been conceptually superceded by the New Zealand Soil Classification, it is still being used by most land managers. This is because 95% of the published data about soils uses the New Zealand Genetic Soil Classification. Most if not all soil maps of New Zealand have been made using the New Zealand Genetic Soil Classification.

The New Zealand Genetic Soil Classification system is no longer used by researchers, especially those publishing internationally

User friendliness/public and decision maker understanding

The full name of most soils is long. Generally these can be shortened. The common name terminology has been widely used and is generally understood by land managers.

Framework strengths

Current limitations of framework

References

Taylor, N.H. 1948. Soil map of New Zealand 1:2 027 520 scale. DSIR, Wellington.

Taylor, N.H.;Cox,J.E. 1956. The soil pattern of New Zealand. New Zealand Institute of Agricultural Science Proceedings.17p.

Taylor, N.H.;Pohlen, I. 1962. Classification of New Zealand soils. Pp 15-33 In Soils of New Zealand, Part 1. Soil Bureau Bulletin 26(1). 142p with 1:1,000,000 scale soil map of New Zealand. DSIR, Wellington.