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This function downloads a generalized representation of the geographic extent of any single taxon from the top 4 levels of Soil Taxonomy, or taxa matching a given formative element used in Great Group or subgroup taxa. Data are provided by SoilWeb, ultimately sourced from the current SSURGO snapshot. Data are returned as raster objects representing area proportion falling within 800m cells. Currently area proportions are based on major components only. Data are only available in CONUS and returned using an Albers Equal Area / NAD83(2011) coordinate reference system (EPSG: 5070).


  level = c("order", "suborder", "greatgroup", "subgroup"),
  formativeElement = FALSE,
  timeout = 60,
  as_Spatial = getOption("soilDB.return_Spatial", default = FALSE)



single taxon label (e.g. haploxeralfs) or formative element (e.g. pale), case-insensitive


the taxonomic level within the top 4 tiers of Soil Taxonomy, one of 'order', 'suborder', 'greatgroup', 'subgroup'


logical, search using formative elements instead of taxon label


time that we are willing to wait for a response, in seconds


Return raster (RasterLayer) classes? Default: FALSE.


a SpatRaster object (or RasterLayer when as_Spatial=TRUE)


See the Geographic Extent of Soil Taxa tutorial for more detailed examples.

Taxon Queries

Taxon labels can be conveniently extracted from the "ST_unique_list" sample data, provided by the SoilTaxonomy package.

Formative Element Queries


The following labels are used to access taxa containing the following formative elements (in parentheses)

  • acr: (acro/acr) extreme weathering

  • alb: (alb) presence of an albic horizon

  • anhy: (anhy) very dry

  • anthra: (anthra) presence of an anthropic epipedon

  • aqu: (aqui/aqu) wetness

  • argi: (argi) presence of an argillic horizon

  • calci: (calci) presence of a calcic horizon

  • cry: (cryo/cry) cryic STR

  • dur: (duri/dur) presence of a duripan

  • dystr: (dystro/dystr) low base saturation

  • endo: (endo) ground water table

  • epi: (epi) perched water table

  • eutr: (eutro/eutr) high base saturation

  • ferr: (ferr) presence of Fe

  • fibr: (fibr) least decomposed stage

  • fluv: (fluv) flood plain

  • fol: (fol) mass of leaves

  • fragi: (fragi) presence of a fragipan

  • fragloss: (fragloss) presence of a fragipan and glossic horizon

  • frasi: (frasi) not salty

  • fulv: (fulvi/fulv) dark brown with organic carbon

  • glac: (glac) presence of ice lenses

  • gloss: (glosso/gloss) presence of a glossic horizon

  • gypsi: (gypsi) presence of a gypsic horizon

  • hal: (hal) salty

  • hemi: (hemi) intermediate decomposition

  • hist: (histo/hist) organic soil material

  • hum: (humi/hum) presence of organic carbon

  • hydr: (hydro/hydr) presence of water

  • kandi: (kandi) presence of a kandic horizon

  • kanhap: (kanhaplo/kanhap) thin kandic horizon

  • luvi: (luvi) illuvial organic material

  • melan: (melano/melan) presence of a melanic epipedon

  • moll: (molli/moll) presence of a mollic epipedon

  • natr: (natri/natr) presence of a natric horizon

  • pale: (pale) excessive development

  • petr: (petro/petr) petrocalcic horizon

  • plac: (plac) presence of a thin pan

  • plagg: (plagg) presence of a plaggen epipedon

  • plinth: (plinth) presence of plinthite

  • psamm: (psammo/psamm) sandy texture

  • quartzi: (quartzi) high quartz content

  • rhod: (rhodo/rhod) dark red colors

  • sal: (sali/sal) presence of a salic horizon

  • sapr: (sapr) most decomposed stage

  • sombri: (sombri) presence of a sombric horizon

  • sphagno: (sphagno) presence of sphagnum moss

  • sulf: (sulfo/sulfi/sulf) presence of sulfides or their oxidation products

  • torri: (torri) torric/aridic SMR

  • ud: (udi/ud) udic SMR

  • umbr: (umbri/umbr) presence of an umbric epipedon

  • ust: (usti/ust) ustic SMR

  • verm: (verm) wormy, or mixed by animals

  • vitr: (vitri/vitr) presence of glass

  • xer: (xero/xer) xeric SMR


The following labels are used to access taxa containing the following formative elements (in parenthesis).

  • abruptic: (abruptic) abrupt textural change

  • acric: (acric) low apparent CEC

  • aeric: (aeric) more aeration than typic subgroup

  • albaquic: (albaquic) presence of albic minerals, wetter than typic subgroup

  • albic: (albic) presence of albic minerals

  • alfic: (alfic) presence of an argillic or kandic horizon

  • alic: (alic) high extractable Al content

  • anionic: (anionic) low CEC or positively charged

  • anthraquic: (anthraquic) human controlled flooding as in paddy rice culture

  • anthropic: (anthropic) an anthropic epipedon

  • aquic: (aquic) wetter than typic subgroup

  • arenic: (arenic) 50-100cm sandy textured surface

  • argic: (argic) argillic horizon

  • aridic: (aridic) more aridic than typic subgroup

  • calcic: (calcic) presence of a calcic horizon

  • chromic: (chromic) high chroma colors

  • cumulic: (cumulic) thickened epipedon

  • duric: (duric) presence of a duripan

  • durinodic: (durinodic) presence of durinodes

  • dystric: (dystric) lower base saturation percentage

  • entic: (entic) minimal surface/subsurface development

  • eutric: (eutric) higher base saturation percentage

  • fibric: (fibric) >25cm of fibric material

  • fluvaquentic: (fluvaquentic) wetter than typic subgroup, evidence of stratification

  • fragiaquic: (fragiaquic) presence of fragic properties, wetter than typic subgroup

  • fragic: (fragic) presence of fragic properties

  • glacic: (glacic) presence of ice lenses or wedges

  • glossaquic: (glossaquic) interfingered horizon boundaries, wetter than typic subgroup

  • glossic: (glossic) interfingered horizon boundaries

  • grossarenic: (grossarenic) >100cm sandy textured surface

  • gypsic: (gypsic) presence of gypsic horizon

  • halic: (halic) salty

  • haplic: (haplic) central theme of subgroup concept

  • hemic: (hemic) >25cm of hemic organic material

  • humic: (humic) higher organic matter content

  • hydric: (hydric) presence of water

  • kandic: (kandic) low activity clay present

  • lamellic: (lamellic) presence of lamellae

  • leptic: (leptic) thinner than typic subgroup

  • limnic: (limnic) presence of a limnic layer

  • lithic: (lithic) shallow lithic contact present

  • natric: (natric) presence of sodium

  • nitric: (nitric) presence of nitrate salts

  • ombroaquic: (ombroaquic) surface wetness

  • oxyaquic: (oxyaquic) water saturated but not reduced

  • pachic: (pachic) epipedon thicker than typic subgroup

  • petrocalcic: (petrocalcic) presence of a petrocalcic horizon

  • petroferric: (petroferric) presence of petroferric contact

  • petrogypsic: (petrogypsic) presence of a petrogypsic horizon

  • petronodic: (petronodic) presence of concretions and/or nodules

  • placic: (placic) presence of a placic horizon

  • plinthic: (plinthic) presence of plinthite

  • rhodic: (rhodic) darker red colors than typic subgroup

  • ruptic: (ruptic) intermittent horizon

  • salic: (salic) presence of a salic horizon

  • sapric: (sapric) >25cm of sapric organic material

  • sodic: (sodic) high exchangeable Na content

  • sombric: (sombric) presence of a sombric horizon

  • sphagnic: (sphagnic) sphagnum organic material

  • sulfic: (sulfic) presence of sulfides

  • terric: (terric) mineral substratum within 1 meter

  • thapto: (thaptic/thapto) presence of a buried soil horizon

  • turbic: (turbic) evidence of cryoturbation

  • udic: (udic) more humid than typic subgroup

  • umbric: (umbric) presence of an umbric epipedon

  • ustic: (ustic) more ustic than typic subgroup

  • vermic: (vermic) animal mixed material

  • vitric: (vitric) presence of glassy material

  • xanthic: (xanthic) more yellow than typic subgroup

  • xeric: (xeric) more xeric than typic subgroup


D.E. Beaudette and A.G. Brown


if (FALSE) {
  # soil order
  taxa <- 'vertisols'
  x <- taxaExtent(taxa, level = 'order')
  # suborder
  taxa <- 'ustalfs'
  x <- taxaExtent(taxa, level = 'suborder')
  # greatgroup
  taxa <- 'haplohumults'
  x <- taxaExtent(taxa, level = 'greatgroup')
  # subgroup
  taxa <- 'Typic Haploxerepts'
  x <- taxaExtent(taxa, level = 'subgroup')
  # greatgroup formative element
  taxa <- 'psamm'
  x <- taxaExtent(taxa, level = 'greatgroup', formativeElement = TRUE)
  # subgroup formative element
  taxa <- 'abruptic'
  x <- taxaExtent(taxa, level = 'subgroup', formativeElement = TRUE)
  # coarsen for faster plotting
  a <- terra::aggregate(x, fact = 5, na.rm = TRUE)
  # quick evaluation of the result
  terra::plot(a, axes = FALSE)