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GlobalSoilMap_v01_STATSGO2/effective_cation_exchange_capacity (MapServer)

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Service Description: This service displays the Effective Cation Exchange Capacity theme from the GSM v0.1 based on U.S. General Soil Map (STATSGO2). The Effective Cation Exchange Capacity theme is displayed by three property values; high, low, and representative. Each value displays the depth range in cm.

Map Name: Layers4

Legend

All Layers and Tables

Layers: Description: The "ecec_h", "ecec_l" and "ecec_r" tables are designed to facilitate thematic mapping. The tables are national in extent and can be used in conjunction with the GSM Version 0.1 grid to map effective cation exchange capacity (ecec). The "h", "l", and "r" correspond to "high", "low" and "representative" property values. The "l" represents the minimum low value of all the components within each map unit and is used as an approximate lower confidence limit estimate for the map unit at each depth. For the lower estimate above the representative value "r" (due to incomplete population of high and low values in STATSGO2, and anomalies in the spline), the lower estimate was set to null. The "h" represents the maximum value of all the components within each map unit and is used as an approximate upper confidence limit estimate for the map unit at each depth. For the upper estimate above the representative value "r" (due to incomplete population of high and low values in STATSGO2, and anomalies in the spline), the upper estimate was set to null. The tables can be attached to the raster map layer data using the common "mukey" for spatial mapping. This table represents Effective Cation Exchange Capacity (ecec) soil property. Each table contains 50 columns.
FieldDescription
mukey: Map unit identification key
tot_comps: Total number of components within the map unit
ecectot_r0to5: Value for representative ecec in the 0-5 cm depth interval
cntrb_ecectot_r0to5: Percent (by area) of map unit used for weighted average calculation for 0-5 cm interval
null_pct_ecectot_r_0to5: Percent (by area) of map unit that has missing data for 0-5 cm interval
misc_pct_ecec_r_0to5: Percent (by area) of map unit that is nonsoil material (miscellaneous) for 0-5 cm interval
avail_ecec_r0to5: Number of map unit components that are soil and not null for 0-5 cm interval
missing_ecec_r0to5: Number of map unit components that are nonsoil material or null for 0-5 cm interval
datatype_ecec_r0to5: The type of calculation used to find the value for the map unit (either WM, SC, or OA)
ecec units: meq/100g equivalent to 1 cmol/kg or 10 mmol/kg (GlobalSoilMap specifications)
Columns "mukey" and "tot_comps" are unique. The remaining columns are repeated for each depth: 5to15, 15to30, 30to60, 60to100, 100to200. The "datatype" column is populated with three options:

The U.S. National Soil Survey Center (NSSC) uses pH-7 amonium acetate cation extraction (CEC7) to estimate ECEC for pH values greater than 5.5, and adds 1N KCl extractable Aluminum to that estimate for pH less than 5.5 to approximate ECEC (Soil Survey Laboratory, Staff, 1996; West and Libohova, 2012). Thus ECEC is largely unattributed in the STATSGO2 database where pH is greater than 5.5, hence CEC7 can be used as ECEC above pH 5.5 (West and Libohova, 2012). ECEC (CEC7 + Acidity) was well-attributed at or below pH 5.5 ECEC property values were combined with the CEC values above pH 5.5 to get estimates for all the map units.

Horizon values for each component (soil type) were selected only where the data were not missing and the component kind was not ‘Miscellaneous area’. Miscellaneous areas were excluded since they are dominantly occupied by non-soil materials. Major miscellaneous areas include badlands, beaches, chutes, cinder lands, dams, dumps, dune lands, glaciers, gullied land, lava flows, mined lands, oil-waste land, pits, playas, riverwash, rock outcrop, rubble land, slickens, urban land and water. Detailed descriptions of each category can be found in the National Soil Survey Handbook, Part 627 - Legend Development and Data Collection, Subpart B - 627.10 (U.S. Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI [http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ref/?cid=nrcs142p2_054242 (accessed 14 February 2018)]. The values for each soil type profile were fit with an equal-area continuous smoothing spline. (Bishop et al., 1999; Odgers et al., 2012) with a smoothing parameter, lambda, set at 0.1 for all properties. The generated spline was used to set property estimates at the GlobalSoilMap standard depth intervals (0-5 cm, 5-15 cm, 15-30 cm, 30-60 cm, 60-100 cm, and 100-200 cm (GlobalSoilMap, 2012)). For instances where splined values exceeded the lower and upper bounds the property estimate was “capped” at the nearest sensible bound. The representative standard depth estimates for each profile (i.e. component or soil type), were weighted within each map unit (i.e. group of components mapped together), using the component percentage by area of the map unit as the weights. Miscellaneous areas (non-soil materials) did not contribute to the map unit weighted average so the weighted mean represents only the soils in each map unit. The remaining soil components were scaled to represent 100% of the map unit and weighted accordingly in the calculation of the map unit average. Values for map units dominated by non-soil material, or with more than 50% as ‘Miscellaneous area’ were set to null. After map unit averages for the representative values were calculated for clay, silt, and sand, each property was scaled proportionally to ensure the three properties add up to 100 % equivalent to 1000 g/kg (GlobalSoilMap specifications). Although this had little effect on most of the estimates, it corrects for the small changes induced by splining and averaging the components within each map unit. Deficiencies in the original STATSGO2 database were noticed in that some clay, silt, and sand horizon measurements were missing, set to zero, and/or did not add up to 100%.

Use Limitations: This dataset is not designed for use as a primary regulatory tool in permitting or siting decisions, but may be used as a reference source. This is public information and may be interpreted by organizations, agencies, units of government, or others based on needs; however, they are responsible for the appropriate application. Federal, State, or local regulatory bodies are not to reassign to the Natural Resources Conservation Service any authority for the decisions that they make. The Natural Resources Conservation Service will not perform any evaluations of these maps for purposes related solely to State or local regulatory programs. Digital data files are periodically updated. Files are dated, and users are responsible for obtaining the latest version of the data.
Scale Range: Maximum (zoomed in) 1:250,000, Minimum (zoomed out) 1:1,500,000
Citations: Helmick, J., Nauman, T., Thompson, J., Burkholder, A., Hempel, J., Odgers, N., Libohova, Z., 2017. GlobalSoilMap Version 0.1: Soil property maps from the General Soil Map Database (STATSG02) database for the USA.

Purpose: Providing the public with a GSM v0.1 effective cation exchange capacity theme service.
Creation Date: 2015
Publication Date: 20180124
Revision Date: 20180410
Refresh Cycle: Final product.
Version: 1.0.1
Change Log: Description edits.
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Copyright Text: Soil Survey Staff - West Virginia University, Gridded GlobalSoilMap Property maps (GSM, Version 0.1) for conterminous United States, USDA-NRCS

Spatial Reference: 4326  (4326)


Single Fused Map Cache: false

Initial Extent: Full Extent: Units: esriDecimalDegrees

Supported Image Format Types: PNG32,PNG24,PNG,JPG,DIB,TIFF,EMF,PS,PDF,GIF,SVG,SVGZ,BMP

Document Info: Supports Dynamic Layers: false

MaxRecordCount: 1000

MaxImageHeight: 4096

MaxImageWidth: 4096

Supported Query Formats: JSON, geoJSON, PBF

Supports Query Data Elements: true

Min Scale: 0

Max Scale: 0

Supports Datum Transformation: true



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