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Soil mapping

Taking a soil profile v2

A soil survey (or soil mapping) identifies and records different soils and their locations (soil map units) in the field. Information provided by a soil map and the accompanying report including the description and classification of the soils can be referred to as soil map information.

Historically, these maps and reports were prepared by hand and published as soil survey reports. These days soil information may be mapped and made available electronically (e.g. S-map Online).

Historic soil maps

Maps of the “Soils and Agriculture of the Waimea County” were published at a scale of 1:126,720 based on surveys and mapping undertaken as far back as the 1920s.

The “General Soil Survey of the South Island” (1968) provides an overall picture of soil pattern and basic soil information. The scale was 4 miles to 1 inch. (1:250,000). 

In 1977, the New Zealand Land Resource Inventory (NZLRI) was published at a scale of 1:63,360 and later revised to 1:50,000 bringing together (with some minor mapping improvements) the soil information from the two surveys described above. Although, at a regional scale, the soil information attributed to NZLRI polygons represents the most available soil information in the Nelson City region.

Soil classification

Over the years the way we classify soils (i.e. group them based on similar properties) in New Zealand has changed. The current soil classification used here is the New Zealand Soil Classification (Hewitt 2010).  The classification hierarchy is made up of the Soil Order, which divides into Soil Group and further into Soil Sub-groups. There are 15 Soil Orders found in New Zealand, of which five are represented in the Nelson City region. Individual soils are often referred to by their regional Soil Series names (for example, Waimea or Atawhai soils). The use of Soil Series predates the New Zealand Soil Classification but is still sometimes used to distinguish soils at a finer level of classification than is possible with the New Zealand Soil Classification.

See here for more information on the history of soil classification. 

Soils in the Nelson City region

Soil map information for the Nelson City region is based on the “Soils and Agriculture of the Waimea County” (1966) and the “General Soil Survey of the South Island” (1968). The information includes descriptions of soils, and hard copy soil maps - electronic soil maps are not available, except as part of the soil information provided in the NZLRI polygons. For effective soil management on farms, farm-scale mapping at a scale of approximately 1:5000-1:10,000 is best.

Based on available soil map information, five Soil Orders have been identified in Nelson City region (Figure 1). The five Soil Orders equate to 19 different Soil Series.

 The table below shows some of the main features of the soils in the Nelson City region.

Landform Geology NZSC Soil Series Main features
Coastal sands Sand dunes Recent Tahunanui Sands; weakly developed soils with low fertility; land uses include forestry, pasture, housing and recreation.
Floodplains Alluvium and terrace gravels derived from erosion of mixed sedimentary and volcanic rocks Gley Motukaraka Silt loams formed from marine sediments; poorly drained with low fertility and high soluable salt content; drained areas are used for dairy.
Richmond Clay and silt loams formed from finer, poorly drained sedimentary alluvium; high organic matter, good fertility; mainly used for dairy.
Recent Waimea Clay loams to gravelly loams; well drained with some imperfectly drained; from sedimentary alluvium; high fertility but low potassium; mainly used for horticulture.
Alluvium and terrace gravels derived from erosion of sedimentary rocks Ronga Silt loams with gravelly subsoils; moderately well drained with some well drained; low to moderate fertility; mainly used for pastoral farming.
Terraces Alluvium from slates and shales Brown Rai Silt loams; well drained; moderate to low fertility; land uses include pastoral farming, cropping and plantation forestry.
Alluvium and terrace gravels derived from erosion of mixed sedimentary and volcanic rocks Ranzau Gravelly silt loams; well drained; moderate fertility with low potassium; land uses include horticluture, pasture and houses.
Rolling and hilly Sandstone gravels Brown Wakatu Silt loams; well drained; low fertility; land uses include pastoral farming and cropping.
Calcareous sandstone and shale Wantwood Silt loams; moderate to high fertility; land uses include pastoral farming and housing.
Volcanic rocks (spilites, keratophytes and tuffs) Melanic Sunnybank Silt loam hill soils; well drained; dark brown clay loam subsoils with moderate to high fertility but with low phosphorus; land uses include pastoral farming and cropping.
Rolling, hilly and Steeplands Greywacke, argillite and sandstone Brown Pelorus Silt loam hill and steepland soils; well drained; higher rainfall produces some podzolised soils; low fertility; pastoral farming is limited to the easier topography.
Steeplands A complex mixture of volcanic rocks and altered sedimentary rocks Brown Atawhai Silt loam steepland soils; well drained with some moderately well drained; low to moderate fertility; land use is mainly pastoral farming, with large areas of scrub.
Dunite and serpentine Dun Sandy loam (over silt loam) steepland soils; well drained; shallow soils with very low fertility; land use is mainly native forest reserve with some plantation forestry.
Greywacke, argillite and sandstone Lee Silt loam steepland soils; well drained; shallow soils with moderate fertility; land use is mainly scrub with  some pastoral farming where gentler slopes allow.
Patriarch Silt loam steepland soils; well drained; very shallow soils with very low fertility; land use is native scrub and forest.
Whangamoa Silt loams steepland soils; well drained; shallow soils with moderate to low fertility; mainly reverted scrub, some pastoral farming and suitable for plantation forestry.
Alluvium and colluvium gravels derived from  sedimentary rocks Rai Silt loam steepland soils; well drained; higher rainfall produces some podzolised soils; low fertility; pastoral farming is mainly limited to the easier topography.
Granodiorite and diorite Melanic Otu Silt loam steepland soils; well drained; shallow soils with low to moderate fertility; land use is mainly scrub and forest, some plantation forestry and pastoral farming where gentler slopes allow.
Marble and limestone Pikikiruna Sandy loam steepland soils; moderately well drained; low to moderate fertility; mostly native forest with pastoral farming on easier topography.
Greywacke, argillite and sandstone Ultic Ketu Silt loam steepland soils; well drained; shallow soils with with moderate to low fertility; mainly used for plantation forestry and pastoral farming with some indigenous forest. 

 

 

 soil orders NCC

The New Zealand Soil Classification “Soil Orders” for Nelson City region.

 soil series NCC

The mapped “Soil Series” for Nelson City region.

References

Chittenden, E.T., Hodgson, L., Dodson, K.J., 1966: Soils and agriculture of Waimea County, New Zealand, scale 1:126 720. Soil Bureau Bulletin 30. Wellington, DSIR.

DSIR (1968) General Survey of the Soils of the South Island, New Zealand. Soil Bureau Bulletin 27. Wellington, DSIR.