FedData (version 2.5.7)

get_ssurgo: Download and crop data from the NRCS SSURGO soils database.

Description

This is an efficient method for spatially merging several different soil survey areas as well as merging their tabular data.

Usage

get_ssurgo(template, label, raw.dir = "./RAW/SSURGO",
  extraction.dir = paste0("./EXTRACTIONS/", label, "/SSURGO"),
  force.redo = FALSE)

Value

A named list containing the 'spatial' and 'tabular' data.

Arguments

template

A Raster* or Spatial* object to serve as a template for cropping; optionally, a vector of area names [e.g., c('IN087','IN088')] may be provided.

label

A character string naming the study area.

raw.dir

A character string indicating where raw downloaded files should be put. The directory will be created if missing. Defaults to './RAW/SSURGO/'.

extraction.dir

A character string indicating where the extracted and cropped SSURGO shapefiles should be put. The directory will be created if missing. Defaults to './EXTRACTIONS/SSURGO/'.

force.redo

If an extraction for this template and label already exists, should a new one be created? Defaults to FALSE.

Details

get_ssurgo returns a named list of length 2:

1. 'spatial': A SpatialPolygonsDataFrame of soil mapunits in the template, and

2. 'tabular': A named list of data.frames with the SSURGO tabular data.

Examples

if (FALSE) {
# Extract data for the Village Ecodynamics Project 'VEPIIN' study area:
# http://village.anth.wsu.edu
vepPolygon <- polygon_from_extent(raster::extent(672800,740000,4102000,4170000), 
     proj4string='+proj=utm +datum=NAD83 +zone=12')

# Get the NRCS SSURGO data (USA ONLY)
SSURGO.VEPIIN <- get_ssurgo(template=vepPolygon, label='VEPIIN')

# Plot the VEP polygon
plot(vepPolygon)

# Plot the SSURGO mapunit polygons
plot(SSURGO.VEPIIN$spatial, lwd=0.1, add=T)

# Or, download by Soil Survey Area names
SSURGO.areas <- get_ssurgo(template=c('CO670','CO075'), label='CO_TEST')

# Let's just look at spatial data for CO675
SSURGO.areas.CO675 <- SSURGO.areas$spatial[SSURGO.areas$spatial$AREASYMBOL=='CO075',]

# And get the NED data under them for pretty plotting
NED.CO675 <- get_ned(template=SSURGO.areas.CO675, label='SSURGO_CO675')

# Plot the SSURGO mapunit polygons, but only for CO675
plot(NED.CO675)
plot(SSURGO.areas.CO675, lwd=0.1, add=T)
}