NSSH Amendment 15

April 2008

This is a summary of changes to the National Soil Survey Handbook (NSSH). The official copy of the NSSH is in HTML format and MSWord files at http://soils.usda.gov/technical/handbook/.

Exhibit 618-11 – Rock Fragment Modifier of Texture

1. The previous exhibit is replaced in its entirety. The previous guide inappropriately skewed the modifier toward “gravelly” where there are significant amounts of cobbles and stones.
    
2. The previous exhibit applied inconsistent weighting factors across classes of total rock fragments, regardless of rock fragment composition. The new exhibit maintains the same weighting factors across all classes of total rock fragments, thereby providing the user with a more realistic portrayal of the soil’s limitations.
    
3. The current exhibit omitted “bouldery” as a possible modifier. The new exhibit corrects this.
    
4. An interactive Microsoft Excel spreadsheet is created to calculate rock fragment modifiers for flat and nonflat rock fragments.

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