Polaris 30m Probabilistic Soil Properties US¶

Probabilistic Remapping of SSURGO (POLARIS) soil properties—a database of 30-m probabilistic soil property maps over the contiguous United States (CONUS). The mapped variables over CONUS include soil texture, organic matter, pH, saturated hydraulic conductivity, Brooks-Corey and Van Genuchten water retention curve parameters, bulk density, and saturated water content.

Variable	Description	Units
silt	silt percentage	%
sand	sand percentage	%
clay	clay percentage	%
bd	bulk density	g/cm3
theta_s	saturated soil water content	m3/m3
theta_r	residual soil water content	m3/m3
ksat	saturated hydraulic conductivity	log10(cm/hr)
ph	soil pH in H20	N/A
om	organic matter	log10(%)
lambda	pore size distribution index (brooks corey)	N/A
hb	bubbling pressure (brooks corey)	log10(kPa)
n	measure of the pore size distribution (van genuchten)	N/A
alpha	scale parameter inversely proportional to mean pore diameter (van genuchten)	log10(kPa-1)

Read the original paper here and cite the work using

Chaney, Nathaniel W., Budiman Minasny, Jonathan D. Herman, Travis W. Nauman, Colby W. Brungard, Cristine LS Morgan
Alexander B. McBratney, Eric F. Wood, and Yohannes Yimam. "POLARIS soil properties: 30‐m probabilistic maps of soil properties
over the contiguous United States." Water Resources Research 55, no. 4 (2019): 2916-2938.

Data characteristics¶

POLARIS provides a spatially continuous, internally consistent, quantitative prediction of soil series. It offers potential solutions to the primary weaknesses in SSURGO: 1) unmapped areas are gap-filled using survey data from the surrounding regions, 2) the artificial discontinuities at political boundaries are removed, and 3) the use of high resolution environmental covariate data leads to a spatial disaggregation of the coarse polygons.

The dataset is available at varying depth from surface, while the statistics provided include mean, mode , median and percentile values, only median values have been included as part of the collection created.

Depth from Surface
0-5 cm
5-15 cm
15-30 cm
30-60 cm
60-100 cm
100-200 cm

Overall datasets include processing approximately 80,000 files which have been converted into individual images within a collection per property at varying depth. So for example collection bd_mean includes bd_0_5 and represents a single image for contiguous US with bd value at surface depth of 0-5 cm from surface.

Notes from Data providers¶

05/01/2019 - The variables hb, alpha, ksat, om are in log10 space.
05/01/2019 - Due to file size constraints, the 1 arcsec database is split into 1x1 degree tiffs. Each variable/layer/statistic has its own virtual raster that acts as the "glue" of all the smaller 1x1 degree chunks. For more information on virtual rasters see https://www.gdal.org/gdal_vrttut.html.
06/02/2019 - The variables hb and alpha were originally reported to have the units of log10(cm) and log10(cm-1) respectively. This was a typo. The correct units are log10(kPa) and log10(kPa-1) respectively.

Earth Engine Snippet: HiHydro Additional Layers¶

var bd_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/bd_mean');
var clay_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/clay_mean');
var ksat_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/ksat_mean');
var n_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/n_mean');
var om_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/om_mean');
var ph_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/ph_mean');
var sand_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/sand_mean');
var silt_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/silt_mean');
var theta_r_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/theta_r_mean');
var theta_s_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/theta_s_mean');
var lambda_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/lambda_mean');
var hb_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/hb_mean');
var alpha_mean = ee.ImageCollection('projects/sat-io/open-datasets/polaris/alpha_mean');