Soil Surveys

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Soil Surveys

• Bryan McElvany
• Warnell School of Forest Resources
• Patrick Davies

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Soil Taxonomy

• Soil Taxonomy (soil classification) is a method
  of classifying soils into groups.
• This system is a hierarhical method of grouping
  soils by similar characteristics.
• 12 main groupings of soils into Orders exist.
• These Orders are broken down into smaller groups
  until a Soil Series is reached.

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Soil Orders

• Andisols - Volcanic
• Aridisols - Desert
• Gelisols - Frozen
• Histosols - Organic
• Vertisols Shrink Swell
• Inceptisols - Infant
• Entisols - Resistant
• Alfisols Moderately Weathered
• Ultisols Highly Weathered
• Oxisols - Tropical
• Spodosols - Flatwoods
• Mollisols - Prairies

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Soil Series

• The lowest category in the soil taxonomy system.
  Over 20,000 soil series have been defined. They
  are generally named after a location near where
  they were first described.
• Control section the part of the soil on which
  classification is based. The thickness varies
  among different kinds of soil, but mainly is up
  to 80 inches deep.

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Soil Survey

• Soil surveys are the primary references available
  to help land managers determine the potentials
  and limitations of the soils.
• Soil surveys are a compilation of maps and
  interpretive data.
• Published by the USDA Natural Resources
  Conservation Service (NRCS).
• Published on a county or county group basis.

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Soil Mapping

• Soil mapping is performed by soil scientists on
  the ground.
• These maps are generally conducted on the soil
  mapping unit level.
• Soil mapping units are generally soil series or
  soil complexes.
• Soil complex is a grouping of 2 or more soil
  series that are so interconnected that it is not
  feasible to map them independently.

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Soil Survey Use
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Soil Association Map

• Soil Associations are soils that are similar in
  many characteristics.
• The first map in the survey is the soil
  association map.
• Good for getting a good idea of soils on a large
  scale.

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Detailed Soil Maps

• Produced on aerial photographs
• Permanent features are mapped (highways, ponds,
  rivers, etc)
• Soil mapping units are delineated and labeled
  with a code (numbers or letters)

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Soil Mapping Precision

• Soils are delineated with a line on the map.
• On the ground there is rarely a sharp division
  between soils.
• The change from one soil to another may be very
  gradual.
• Soil series descriptions are also for the typical
  example, variations between locations occur as
  well.

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Soil Series Descriptions

• General characteristics are described in this
  section. Parameters such as slope, drainage,
  fertility, and landscape position are described.
• A detailed soil profile description is also
  included in this section.

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Soil Tables

• Several tables are included in the soil survey.
  They contain information on the soil in relation
  to several parameters.
• Engineering properties (buildings, roads, ponds,
  septic systems, landfills, etc.)
• Woodland usage
• Wildlife habitat
• Crop suitability

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The History of Soil Surveys

• Soil surveys have been produced since the early
  1900s.
• Surveys are in various states of becoming
  outdated.
• NRCS has to balance the effort to map new areas
  with updating previously mapped areas.

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The Future of Soil Surveys

• New technology is pushing the soil survey program
  in new directions.
• Computer copies of surveys are becoming
  available.
• GPS, GIS systems of mapping will become the
  standard.
• This leads to improvements on the ability to use
  the surveys on the ground (precision farming etc)

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The End

• Thanks