The Danish Soil Classification

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The Danish Soil Classification

• From 1939 to 1975 the farmland area dropped from
  32.000 sqkm to 28.000 sqkm
• It raised a need for soil maps for planning and
  administration purposes at national and county
  level
• The Danish government decided to finance a
  national soil mapping

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The Danish Soil Classification

• 1975-1980 Soil mapping of the agriculture land
  mainly based on soil texture of the topsoil
• 1980-1985 Additional soil map on subsoil
  texture, landform and wetland and the
  establishment of a Danish pedological soil
  analytical database
• 1985-1990 Modelling and thematic maps

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Basic requirements

• The areas should be classified on the basis of
  permanent stable characteristics
• There should be a national standard code of
  reference that would make it possible to classify
  as uniform as possible
• The results should clearly illustrate the range
  of fertile and infertile soils
• The maps should be made in such a way that they
  might be used in future regional planning
• The mapping should be finished within 3 years
  (price app. 600.000 Euro)

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The soil map, scale 150.000

• Classified area
• Texture of the plowlayer and subsoil (12 classes)
• Slope (3 classes)
• Subsoil geology (app. 50 classes)
• Not classified area
• Urban zone
• Forest
• Coastal dune sands, small arable areas, lakes etc

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Organisation

• In December 1975 ADK was established to undertake
  the soil sampling, database handling and
  construction of the maps at scale 150.000.
• Crew 3 AC and 1 technician some students from
  the Universities.
• The soil sampling was done by local agronomists
  and the soil analyses were done at a research
  laboratory.

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Mapping slopes and surface geology

• Slope classes
• Three slope classes delineated on topographic
  maps at scale 125000
• lt6 degrees, 6-12 degrees and gt12 degrees
• Surface geology
• Dominant surface geology is shown in a 25ha
  grid based on the Danish geological surveys map
  which cover 75 of the country

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Soil sampling for texture analyses

• ADK distributed topographic maps and
  questionnaires to local agronomists (advisors)
  who registered existing texture analyses
• The agronomists were asked to recommend suitable
  locations for forthcoming soil sampling
• ADK combined the recommendation with infor-mation
  on topography and surface geology and the final
  sampling sites were chosen
• The agronomists undertook the soil sampling.
  36000 topsoil samples (0-20cm) and 6000 subsoil
  samples (35-55cm) were taken

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Samplingsites
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Analyses

• Texture 2mm, 20mm, (63mm), 200mm, 2000mm
• Hydrometer method and sieving
• Organic C Determined by a Leco-apparatus
• Lime Determined by treating the samples with HCl
• and capture the carbondioxide in
• bariumhydroxide

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Texture analyses
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Sample library
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Texture classification
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Map construction

• The borders on the soil maps were drawn by the
  crew at ADK in cooperation with the local
  agronomists
• The drawing of the borderlines was based on the
  texture analyses, landscape analyses, the surface
  geology maps and the local knowledge from the
  agronomists involved.
• The maps were digitized and all analytical data
  were stored in a database. The software was
  developed as a Ph.D. study at Århus University

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Soil map from Aabenraa
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Soil map of Ribe
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Soil map of Denmark
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Additional soil maps 1980-1985

• Geomorphological map
• Subsoil texture map
• Wetland map
• Potential acid sulfate soil
• Soil map of the forests

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Geomorphological map of Denmark
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Geological Surveys map of Gislum, 125000
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Subsoil texture
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Incircled wetlands on a topographic map
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Wetlands
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Soil chemical and physical data

• By combining the different soil maps an area can
  be characterized as follows
• Topsoil Fine sand (MCC2)
• Subsoil loam (MCC5)
• Drainange not wetland
• Geomorphology Weichsel moraine
• In order to use the soil maps in planning there
  is a huge need for soil profile analytical data,
  chemical as well as physical

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Profile sampling sites
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Soil classification
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Classification system

• The classification based exclusively on field
  observations.
• Describe the main pedological development within
  120cm.
• Describe the presence of gley, lithic and
  limestone contact
• within 3 sections of the profile 0-40, 40-80
  80-120 cm
• Describe the thickness and carbon content of the
  A-horizon
• Describe the presence of fragipan, placic
  horizon,
• degradated B-horizons, cementation, calcic
  horizons

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Danish soil classification system, soil orders
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Danish soil classification system, soil groups

• Group leveI 1 2
  3
• Lessive ranker gley
  podzol
• rendzin pseudogley
  brunjord
• degra
  stagnogley brunsol
• blandings
• typi
• 
  begin at 40-80cm
• Example Degralessive
• Podzolpseudogleytypilessive

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Danish soil classification system, soil series

• Gley, lime and lithic contact in the soil section
  80-120 cm
• Placic horizon, fragipan, cementation, degradated
  Bt or Bs horizons, natric horizons, all within
  1.2 meter depth
• entic A-horizons (lt10cm), kolluvial A horizon
  (40-80cm) humus poor A-horizon (10-40cm thick and
  lt1 OM), humus rich A-horizon (10-40cm thick and
  7-20 OM), histic O-horizon 10-40 cm thick and
  gt20OM.
• Example kolluvial pseudogleyey Typilessive
• entic Degralessive

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Soil name at order, group and series

• Podzol (A-E-Bh-Bs-C)
• 1)Typipodzol
• (gley gt 120cm depth)
• 2) gleyey Typipodzol
• (gley 80-120cm)
• 3) Gleytypipodzol
• (gley 40-80cm)
• 4) Podzolgley (gley 0-40cm)

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Danish pedological soil classification system
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Transformation of soil names to figures
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Finding special soil types

• Podzols with placic horizons
• Order 06 group 26 all podzols series 13
  placic
• Soils with Bt and lime beginning below 80-120 cm
• Order 05 group 25 soils with Bt
• Series 16 17 lime beginning below 80 cm
• Soils with deep A-horizons
• Order 07 A horizons deeper the 80 cm
• series 01 A horizons 40-80 cm deep

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Soil toposequence based on soil classification
for every 25 meter on the pipeline
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(No Transcript)
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Profile description
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Rendzinleptosol on Senon limestoneCambisol in
calcareous loamy till
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Luvisols
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Podzoluvisols
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Regosol and arenosol
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Podzols
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Podzols
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Gleysols
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Inner marsh clay upon a podzol Fluvisol in outer
marsh deposits
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Histosols, one developed on a former podzol
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Histosols
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Soil profile description scheme
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Analyses

• Texture (hydrometer sieving)
• Total carbon (dry combustion)
• Total nitrogen (Kjeldahl)
• Total organic and inorganic phosphorous
• pH(H2O) and pH(CaCl2)
• Lime content (Scheibler)
• Exchangeable acidity at pH 8.1 (Pipers method)
• Exchangeable bases (NH4Ac-extraction at pH7)
• DCB, oxalate and pyrophosphate iron and aluminium
• KCl-extractable H and Al
• Soil water retention (Pressure plate apparatus)

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The use of the databases

• Protection of fertile farmland around towns
• Irrigation need for agriculture production at
  county level
• Irrigation permission
• Hunting zones
• Economical compensation for drainage
• The potential drainage need at national level
• Mapping of potential set aside area
• Carbon storage in Danish soils
• Nitrate leaching from farmland
• Potentially acid sulfate soil

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Example of rules for irrigation permission Ribe
County

• If a farmer wants to irrigate his fields he has
  to get a soil
• texture analyses of the plowlayer and send it to
  the county
• administration. They use the following equation
  derived
• from the soil profile analytical database
• PAW 2.34OM 0.70clay 0.47silt 0.18FS
  3.68
• If PAW lt 20 the farmer may irrigate with 100mm/ha
• If PAW is 20-30 the farmer may irrigate with
  75mm/ha
• If PAW is gt30 the farmer may irrigate with 50mm/ha

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Root Zone Capacity

• Based on the texture analyses from the Danish
  Soil Classification and
• the geological map, soil profiles at 36.000 sites
  are constructed with
• texture in the depth 0-30 cm, 30-60 cm and
  60-120 cm.
• Based on the soil profile analytical database the
  following equations
• between water content at FC and PWP (vol) can be
  established
• FC2.34OM 0.70clay 0.47silt 0.18FS
  3.68, r20.84
• PWP0.55OM 0.63clay 0.18silt 1.12
  r20.89
• Based on root studies an effective root depth for
  crops in relation to soil
• type can be determined and RZC for water in mm
  can be calculated

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Root zone capacity for barley
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Mean irrigation need for barley production
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Potential drainage need
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Set aside areas in Denmark
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FAO 1974 soil map
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EC-soil map scale 11.000.000 - 1985
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FAO 1990
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FAO-soil types on sandy parent materials
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FAO-soil map
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FAO Soil Map Denmark
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FAO-legend
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FAO soil types in relation to landform
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Soil analytical data, proforma 1
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Soil analytical data, proforma 2