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Get SSURGO/STATSGO2 Mapunit Data from Soil Data Access

Source: R/get_component_from_SDA.R, R/get_cosoilmoist_from_SDA.R
fetchSDA.Rd

Functions to download and flatten commonly used tables and from Soil Data Access, and create soil profile collection objects (SPC).

Usage

get_component_from_SDA(
  WHERE = NULL,
  duplicates = FALSE,
  childs = TRUE,
  droplevels = TRUE,
  nullFragsAreZero = TRUE,
  stringsAsFactors = NULL
)

get_cointerp_from_SDA(
  WHERE = NULL,
  mrulename = NULL,
  duplicates = FALSE,
  droplevels = TRUE,
  stringsAsFactors = NULL
)

get_legend_from_SDA(WHERE = NULL, droplevels = TRUE, stringsAsFactors = NULL)

get_lmuaoverlap_from_SDA(
  WHERE = NULL,
  droplevels = TRUE,
  stringsAsFactors = NULL
)

get_mapunit_from_SDA(WHERE = NULL, droplevels = TRUE, stringsAsFactors = NULL)

get_chorizon_from_SDA(
  WHERE = NULL,
  duplicates = FALSE,
  childs = TRUE,
  nullFragsAreZero = TRUE,
  droplevels = TRUE,
  stringsAsFactors = NULL
)

fetchSDA(
  WHERE = NULL,
  duplicates = FALSE,
  childs = TRUE,
  nullFragsAreZero = TRUE,
  rmHzErrors = FALSE,
  droplevels = TRUE,
  stringsAsFactors = NULL
)

get_cosoilmoist_from_SDA(
  WHERE = NULL,
  duplicates = FALSE,
  impute = TRUE,
  stringsAsFactors = NULL
)

Arguments

WHERE

text string formatted as an SQL WHERE clause (default: FALSE)

duplicates

logical; if TRUE a record is returned for each unique mukey (may be many per nationalmusym)

childs

logical; if FALSE parent material and geomorphic child tables are not flattened and appended

droplevels

logical: indicating whether to drop unused levels in classifying factors. This is useful when a class has large number of unused classes, which can waste space in tables and figures.

nullFragsAreZero

should fragment volumes of NULL be interpreted as 0? (default: TRUE), see details

stringsAsFactors

deprecated

mrulename

character. Interpretation rule names

rmHzErrors

should pedons with horizonation errors be removed from the results? (default: FALSE)

impute

replace missing (i.e. NULL) values with "Not_Populated" for categorical data, or the "RV" for numeric data or 201 cm if the "RV" is alsoNULL (default: TRUE)

Value

A data.frame or SoilProfileCollection object.

Details

These functions return data from Soil Data Access with the use of a simple text string that formatted as an SQL WHERE clause (e.g. WHERE = "areasymbol = 'IN001'". All functions are SQL queries that wrap around SDAquery() and format the data for analysis.

Beware SDA includes the data for both SSURGO and STATSGO2. The areasymbol for STATSGO2 is US. For just SSURGO, include WHERE = "areareasymbol != 'US'".

If the duplicates argument is set to TRUE, duplicate components are returned. This is not necessary with data returned from NASIS, which has one unique national map unit. SDA has duplicate map national map units, one for each legend it exists in.

The value of nullFragsAreZero will have a significant impact on the rock fragment fractions returned by fetchSDA. Set nullFragsAreZero = FALSE in those cases where there are many data-gaps and NULL rock fragment values should be interpreted as NULLs. Set nullFragsAreZero = TRUE in those cases where NULL rock fragment values should be interpreted as 0.

Additional examples can be found in the Soil Data Access (SDA) Tutorial

See also

SDA_query

Author

Stephen Roecker