1. Soil Mapping/Sample Collection
USDA-NRCS PROTOCOLS:
Soil Mapping/Sample Collection
M.A. Wilson and S.J. Indorante

2. OBJECTIVES To discuss: Geographic partitioning of soils
Scales of data compilation / availability
Sample collection protocols

3. NATIONAL COOPERATIVE SOIL SURVEY
Determines geographic distribution of soils:
landscape models
maps
map unit/series descriptions
point analytical data
taxonomic classifications
interpretations/predictions

4. SOIL
A natural body composed of solids, liquids, and gases that occur on the land surface, occupying space, with one or more of the following:
Horizons or layers distinguishable from parent material by pedogenic processes
Ability to support rooted plants in a natural environment

5. Soil Genesis Model S = f (CL, O, R, P, T)
Climate
Organisms
Relief
Parent Material
Time
Factors interact
to create natural
bodies on the
landscape in a
predictable
manner

6. Soil-Landscape Paradigm
In a geographic area, only a small number of repeating soil-landscape units occur
Observable discontinuities exist between conterminous areas of different soil-landscape units

7. Common Mapping Scales
Used in Soil Survey

8. Mapping Soil Geography
Landscape (1:100,000)

9. Soil-Landscape Units
(Landscape Scale)

10. Mapping Soil Geography Landform and Components
(1:25,000)

11. (Landform Component Scale)
Soil-Landscape Units
(Landform Component Scale)

12. The Mapped Soils Mapping Units are the basic units for identifying
Map Unit Label
Mapping Units
are the basic
units for identifying
soil geographic order
in a soil survey

13. Soil Correlation “Natural families of soil delineations
that can be interpreted similarly
are the ultimate and elusive goal
of soil mapping and classification.”
(Hudson, 1992)
The natural families created
are mapping units.

14. Systematic Variability of Soil Properties
Attributable to a known cause
Gradual or marked change in properties related to landform, geomorphic elements, and soil forming factors.
Distribution patterns must be related to landscapes and geomorphic surfaces for effective soil survey operations.
(Wilding and Drees, 1983)

15. Problems of Scale
Variations in soil properties range from megascopic (physiographic region and landforms) to microscopic in scale.
Relationship between systematic and random variability is likely to be scale dependent.
(Upchurch and Edmonds, 1991)

16. Sample Collection
Protocols

17. PEDON Smallest volume of soil that can be used to describe and sample
the soil to represent
the landscape unit
Minimal horizontal area is 1m2,
but can range to 10m2 depending
on variability

18. PEDON
Sampled by NRCS scientists and National Cooperative Soil Survey (NCSS) partners at universities, state, and other federal agencies.
Sites are usually selected to represent a central concept of a soil series.
Point data is part of the soil survey standard.

20. DETAILED MORPHOLOGY

21. Soil Taxonomy
Classification system used by the NCSS for identifying and labeling soils in mapping units.
Nomenclature identifies soil properties

22. Order: Vertisols
Suborder: Aquerts
Great Group: Epiaquerts
Subgroup: Chromic Epiaquerts
Family:
Very-fine, smectitic, thermic
Series:
Sharkey

23. SOIL SERIES Lowest category in the U.S. System of Soil Taxonomy
Conceptualized class of soil bodies on the earth’s surface
More restrictive limits than higher taxa.
Soil series serve as the means to transfer soil information and research knowledge from one soil area to another.

24. OFFICIAL SERIES DESCRIPTION

25. SERIES RANGE IN PROPERTIES

27. The Pedon Concept--
Extending limited point data to geographic coverage

28. Soil Observation and Measurement - Pedon Data A B R C Measurement

29. Land resource Regions

30. Map based on STATSGO data

31. Map
Based on
SSURGO
Data

34. CONCLUSIONS
The National Cooperative Soil Survey uses the model of soil genesis and the soil landscape paradigm to define landform components and soils.
Products include point morphological/analytical data with maps at various scales designed for land-use planning and interpretations.