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Soil restrictive layer

kfreemankfreeman Member
edited August 2014 in RIOS

I have calculated Depth to Any Soil Restrictive Layer for three counties in Alabama and Florida using ssurgo data in Soil Data Viewer 6.1 The result is that no soil restrictive layer is found anywhere, except for a few hectares here and there that are in the 50 to 100cm Category.
The attribute documentation says that: If no restrictive layer is described in a map unit, it is represented by the "> 200" depth class. Three parameters available were and I filled them as follows:

- Aggregation Method = Weighted Average
- Component Percent Cutoff - left blank (all components considered)
- Tie-Break Rule = Lower

How can I tell if this is a valid result? If it is not valid, what would an alternative calculation be for soil depth?



  • Kathy, that sounds like it may be an issue with the particular NRCS data for your FL/GA focal area? If you're getting some areas that do return a plausible depth (50-100cm), then perhaps the components are spotty elsewhere?

    I've had reasonably good luck with the GSSURGO data, but I'm only using it (via ArcSWAT) to key to the SWAT SSURGO database. Assuming you don't want to actually build SWAT, you could just grab the mdb here:

    And then extract the ZMAX values for your relevant SSURGO soil names/classes.

  • Hi Dan,

    I did look at the ZMAX values in the SWAT_US_SSURGO_Soils for the Florida counties and it had essentially the same result. Subsequently, we did get a response from the NRCS that really there is no restrictive layer as defined by the Web Soil Survey within 200cm in our study area counties, the western Florida Panhandle. There are soils that have a perched water table within 200cm during the wet season - different than a "restrictive layer".

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