Appendix H — Changes in the third edition

Modified

March 2, 2026

General

  • The structure of the book has been updated and how has four major sections: Soil setting, Soil Profile, Soil Horizons, and Soil Interpretations.
  • Inherently numeric properties are now preferentially recorded as numbers; either single measurements, median-plus-range, or low-high range as appropriate. Options for classifying numeric parameters for ease of communication are presented in the Soil Interpretations section.
    Rationale: Numeric data recorded as ranges in the field has limited re-use potential (in that it can’t be combined with the same data recorded against other classifications or as numbers) and the ranges have an inherently limited resolution. Many numeric soils parameters have no inherent natural breaks, but patterns in their distribution can emerge in specific landscapes or over certain scales of examination. Recording such data to classes reduces the odds of ever revealing those patterns clearly.
  • Parameters required for the New Zealand Soil CLassifciation (NZSC) have been updated where needed in alignment with the simultaneous review of that document
  • Horizon name protocols remain substantially the same, with some updates to bring the schema into alignment with the NZSC.

Soil Setting (formerly ‘Site Data’)

This section has been loosely structured around the major soil forming factors.

  • ADD Chapter Parent material, discussing ways to record geological and lithological information. General commentary on the use of geological maps is included but there is no requirement to record geological map code or similar, due to scale and purpose differences. A new rock class list organised around origin, mineralogy, grain size and hardness is also added.
    Some commentary on available research-grade rock type vocabularies is also included. Longer term, the description manual should consider adopting one of these, but they need further development.
  • ADD Chapter Soils, describing additional sources of New Zealand soils knowledge.
  • UPDATE ‘Location of profile position’ to Location and describe modern methods of recording site location, including elevation.
  • UPDATE ‘Annual precipitation’ to Climate and Weather, build out a broader discussion of recommended climate and weather parameters, and available data sources.
  • UPDATE ‘Geomorphic position’ to Geomorphology, with a more structured method of geomorphology description.
    • The ‘P’, ‘S’, ‘E’ scales of examination previously described on p. 12 of Milne et al. (1995) are loosely retained as Landscape, Landform and Site, but the details of their expression differ.
    • Slope and aspect are retained as optional measurements. How they are recorded varies with scale of examination.
    • Slope length and width are no longer required to be measured in-field, as this is generally impractical and slope width has no inherent relevance to soil character. Options for computation from Digital Elevation Models (DEMs) or measurement in GIS are mentioned.
    • ‘Wave length and amplitude’ is replaced by the simpler term ‘relief’ and is only recorded at Landscape scale. The definition is the same. A relief classification is added in Relief classification.
    • Assessment of rock outcrop and boulder cover at the site is moved to Surface cover.
    • Geomorphic word descriptors (p.15-22) have been regrouped into the Landscape/Landform structure the highly local ones been moved to ‘natural microrelief’, Natural microrelief.
    • The user is referred to National Committee on Soil and Terrain (2024), p. 38-41 for detailed description of drainage channels, if needed. This is optional.
  • UPDATE ‘Vegetation’ to Biota to allow discussion of when and how to describe other soil-influencing organisms.
    • REMOVE the vegetation description standard (p. 25-31) and replace with cross-references to appropriate existing standards. The RECCE method is now recommended for high-detail work, and the LUC Vegetation classes for routine assessment. The LCDB can be used for rapid assessment.
      Rationale The measurement standards given don’t align with how vegetation is currently recorded by NZ botanists. The ‘Atkinson’ structural classes in Table 2 are not in common use and have the additional problem of grouping all forests into one category, which has very limited discriminatory power. Soils in NZ are known to be heavily influenced by specific types of past and present forest cover, rendering the scheme suboptimal.
  • UPDATE ‘Land use and land-management practices’ to Land cover, land use, and land management. The section now suggests using the proposed NZ Land Use Classification (Law 2024) for land use and the existing Land Cover Database for land cover. Land management codes have been replaced with a discussion of potential land management practices that may be recorded (no codes are provided). The land management practice codes previously listed on p. 33-34 have been migrated to the following code lists:
  • MOVE Erosion and deposition from Soil Setting to Soil Profile.

Soil surface and profile

The soil site

  • UPDATE the definition of a ‘soil site’ to better interact with the landscape/landform geomorphology description system, and account for the variety of soil sampling methods in use (point, plot, transect, etc). The diameter of the surface examined around most sites is reduced from ~100 m to ~20 m; larger areas should be assessed as Landforms.
  • MOVE Chapter ‘Reference data’ into this section
    • ADD location coordinates as required metadata (Site location, and crosslink to more detailed discussion of requirements in chapter ‘Location’)
    • ADD Site purpose Site purpose
    • ADD Site selection method Site selection method
    • REMOVE a requirement for survey title. This is replaced by advocating for a profile identifier that includes a project-level grouping code, and some more generic advice about identifiers.
    • REMOVE requirement for soil series name and classification. These are interpretations, not metadata.
  • ADD a non-optional code-set for exposure type (Exposure type), documenting the method by which the soil was exposed for assessment (pit, auger etc).
  • ADD a requirement to record the maximum depth of observation (or calculate it from horizon depth data)
  • ADD a code list for recording the reason a soil profile did not reach 100 cm
  • ADD a code list for recording recent site disturbances that have the capacity to impact the soil profile description.
  • ADD a ‘site setting’ subsection, summarising the required data points from the ‘soil setting’ chapters. .

Soil surface

  • ADD site-specific slope and aspect recording instructions. These are not optional, unlike slope and aspect at the broader landform and landscape levels. (Slope, Aspect)
  • ADD an assessment of surface cover types, recorded as a compositional set (types observed must add to 100%, see Surface cover). This includes surface stone and outcrop.
  • ADD an optional code list for recording recent disturbances to the soil surface.
  • ADD an optional code list for recording presence and state of surface water (Surface water)
  • ADD an optional code list for recording open surface cracks (Surface cracking)
  • ADD optional code lists for recording natural and anthropogenic microrelief (Microrelief)
  • REMOVE reference to ‘fresh’ or ‘aged’ samples (Milne et al. 1995, p. 35); soil descriptions should only be carried out on fresh soil materials.
  • UPDATE Separate Erosion/Deposition into two sets of three-part descriptive codes to allow easier recording of distinct processes affecting the surface (Erosion, Deposition). Rapid noting of erosion and deposition can be made using site disturbance codes; these are optional extras that allow a little more detail to be communicated.
    • UPDATE gravity-driven erosion codes for international compatibility
    • ADD subtypes of wind deposition for volcanic ash, sand and silt
    • ADD subtypes of water deposition for flood, storm surge and glacial action

Defining soil horizons

  • ADD a clear statement about the differences between the land surface, the soil surface, and the soil mineral surface
  • ADD separate instructions for recording horizon depths, based on whether a large section of profile is visible and on whether detailed assessment is desired (Boundary distinctness)
  • ADD guidance on accurately recording horizon boundaries on steep slopes (see Important 11.1)
  • CHANGE boundary shape by making ‘occluded’ its own option rather than a modifier placed on the other four categories. It is also renamed to ‘discontinuous’. This improves international compatibility (Boundary shape)
  • CHANGE boundary width code ‘D - Distinct’ to ‘C - Clear’ to avoid duplicate short codes (D is also used for Diffuse).
  • ADD a clear statement about when to switch from recording a diffuse horizon transition to defining a new horizon. 30 cm is the proposed cutoff. (Boundary distinctness)
  • ADD a section about how to record infill features (Infill features)
  • REMOVE Table 3 ‘soil water state and soil water potential’ in favour of using the soil water status codes in Table 4. Applying Table 3 correctly requires a tensiometer and/or laboratory data. The schema in Table 4 aligns more closely with international soil water status description requirements.
  • ADD a section on how to record parent materials on a per-horizon basis, including lithology, weathering state, and origin Parent materials. Note that the existing weathering status schema from Milne has been retained for describing the weathering status of profile rock fragments specifically (see Rock fragment weathering) and replaced here with the schema of Juilleret et al. (2016), slightly modified. The parent material origin code list has been developed from the schema in Webb and Lilburne (2011).

Soil horizons

Soil architecture

This section comprises a considerable revision of the ‘Macrofabric’ section of Milne et al. (1995). Components are more clearly separated and options for both rapid and detailed assessment are given.

  • UPDATE structure grade to describe a clear gradient of progressively stronger development (Single-grain –> Massive –> Weak –> Moderate –> Strong). Clearly define apedal/pedal in text.
  • ADD structure origin after the proposal of Anderson et al. (2024) to distinguish between pedogenic, geogenic, and human-induced structural units. This is optional; not recording it assumes all structures are pedogenic.
    Rationale: adding this parameter allows more effective description of C and R horizon structural characteristics, and more clearly highlights human effects on structure e.g. tillage and compaction.
  • ADD structural unit shape ‘angular blocky’. Consistent with international standards; useful for the extremely squared-off peds that can be observed in, e.g., Pumice soils.
  • REMOVE structural unit shape ‘tabular’. Exists in no other system, appears to be a synonym for platy.
  • REMOVE structural unit shape ‘cylindrical’. Exists in no other system
  • REMOVE Figure 8 and 9 flowcharts - redundant
  • REMOVE shape options ‘botryoidal’ and ‘stellate’ as their utility is unclear
  • REMOVE the requirement to measure inclination of all soil macrofabric components
  • Parts of the former Appendix 6 ‘Procedures for describing macrofacbric’ have been moved into this section, providing clear instructions on how to assess structure.
  • UPDATE detailed description options for rock fragment shape to align with modern standards (Rock fragment shape)
  • UPDATE root recording to align with the schema in ISO 25177:2019, focusing on counts per 10 sq cm. Counts may be split by size if desired. Root position in the profile should also be recorded.
  • UPDATE list of void types to provide simpler options. Rename Krotovina to Tunnel to reduce jargon.
  • UPDATE Clearly separate the description of large voids from small pores.
  • MOVE description of structural unit surface features, concentrations, and infilled voids to ‘Secondary Features’.
  • ADD optional detailed description terms for artefacts.
  • ADD description options for subsolum geogenic features - bedding planes and rock fracture patterns.

Soil colour

  • ADD clear instructions for accurately recording colour in the field, as well as notes about colour vision acuity and the use of technology like colour sensors and cameras
  • ADD a direct statement about the definition of the matrix colour, as it differs from most other systems which choose based on areal dominance alone.
  • ADD codes for colour pattern type. NB Patterns from mixing by mechanical or biological means are not distinguished as the presence of such disturbances is recorded in several other ways (site disturbance, horizon names, secondary features)
  • ADD an optional short-code list for simplified colour recording. This may be applied to patterns and even other soil solids if desired but cannot be used for recording matrix colour(s).

Soil texture

  • CHANGE the recording system to allow texture classes that describe the fine earth, gravel and organic matter content together. The system aligns with NZSC requirements and also with the way texture is recorded in geotechnical work. The boundaries of the fine-earth texture classes and groups remain unchanged, as do the component particle size limits.
  • ADD commentary clarifying the differences between hand texture and laboratory particle size analysis
  • ADD a table of clay/silt/sand ranges for the NZ texture triangle
  • UPDATE the triangle diagram for better visual clarity
  • ADD an option for rapid texture assessment, compatible with S-Map and the NZSC
  • UPDATE description options for organic materials
  • UPDATE description options for rock fragments in a texture context (more detailed description is also possible using Rock fragments)
  • REMOVE the von Post scale for organic matter decomposition

Secondary features

  • ADD options for detailed descriptions of pans
  • UPDATE description of concentrations to allow rapid or detailed assessment
  • UPDATE code lists for concentrations, pans, coatings and pressure features to separate the various concepts more clearly and provide rapid and detailed assessment options for both.
  • ADD a note about distinguishing pedogenic lamellae and geogenic lamina as well as when and how to describe them in a profile
  • ADD a subsection on cryofeatures. No new code lists or criteria are defined at this point due to lack of available profile data, but the section points to other parts of the standard that may be used to highlight cryofeatures in a profile morphology description. These align with the new NZSC appendix on Cryic Soils.

Consistence tests

  • ADD infobox discussing which tests may be required when classifying against the NZSC
  • Consistence tests have been re-written with clear, step by step instructions. The evaluation criteria are unchanged, except for the following:
  • REMOVE reference to the use of handheld penetrometers and Singleton blades, as these are no longer common practice. Notes about their origin and previous use are retained to give context to legacy literature.

Field tests

  • Chemical field tests have been rewritten with clear, step by step instructions and are accompanied by equipment lists and improved safety warnings.
  • ADD infobox discussing which tests may be required when classifying against the NZSC
  • REMOVE instructions for sand content by boiling oxalate, P-retention, and organic properties; these should be done in the laboratory.

Soil Interpretations

Horizon notation

  • Horizon naming conventions are largely unchanged, but the structure of the section has been rearranged and some wording updates have been made to many definitions to align them better with the NZSC
  • CHANGE ‘L’ horizon name from describing fresh leaf litter to describing organic horizons developing under largely unsaturated conditions (this replaces both F and H). This allows a parallel set of horizons to those used for peats (Lf, Lh, Lm) and aligns more closely with the texture code system. The former F horizon would now be recorded as ‘Lm’ and H as ‘Lh’. ‘Lf’ is effectively a new option for organic material that is no longer fresh but still little-decomposed, most likely due to having a high fibre and/or lignin content (e.g. palm fronds). Fresh litter presence at a site is now noted using the surface cover codes (Surface cover).
  • ADD example profile descriptions demonstrating the use of lithological discontinuity codes and the buried horizon prefix.
  • ADD a prefix ‘e’ for signifying Anthropic horizons. Guidance for use is in Anthropogenic horizons.
  • REMOVE horizon Cu - ‘u’ considered redundant.
  • CHANGE ‘e’ suffix to ‘u’ for Fluid horizons and remove reference to ‘unripe’ concept

Profile behaviour

This is a new section, containing drainage and other profile interpretations:

  • ADD assessment of horizon-level drainage class to underpin profile-level summaries and allow more detailed drainage data to be recorded
  • ADD instructions for assessing permeability on a per horizon and per profile level. This system is aligned with permeability as it is defined in Webb and Lilburne (2011) for the soil Family
  • ADD instructions for identifying and recording rooting depth restrictions. This system is aligned with root barriers as they are used in S-Map but includes some more specific options.

The New Zealand Soil Classification

  • This is a new section, connecting parts of the description standard to where they might be needed to support a soil classification. Features required to classify the soil are listed and cross-linked down to Sibling level.

Appendices

  • Appendices 10, 11 and 12 have been moved into the main body of the document
  • Appendices 1 and 2 now appear in Appendix E.
  • Appendices 3-9 are considerably out of date in places and may no longer reflect standard field practice. Interest in updating their content is being canvassed through the external review process.
  • NEW Appendix A - recommended field equipment - for excavation, measurement, small hand tools etc
  • NEW Appendix B - recording data in the field. Some general commentary about paper and computers.
    • New advice on taking effective field photographs
    • New minimum dataset guidance
  • NEW Appendix C - sampling guidance. Some parts of Appendix 9 have been moved in here. Guidance for exposing the profile and setting it up for description using different equipment is included, along with common sampling protocols for profiles and surface bulks. A sampling layout design for monitoring is included which aligns with the method currently used for soil carbon monitoring in New Zealand.
  • NEW Appendix D - data model. Diagrams of how the data points in the document fit together in a relational database model; clear indications of must-have and nice-to-have parameters.
  • NEW Appendix E - Classifying numeric measures. Contains classification schema that are commonly applied to various numeric parameters (slope, aspect, relief, abundance, size)
  • NEW Appendix F - correlations. Shows how the standard can be worked in with other land assessment systems used in New Zealand.
  • NEW Appendix G - Land provinces. Contains the extended definitions of provinces listed in Province.