Soil Properties

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• Soil Properties
• versus
• Soil Interpretations

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• Soil Erodibility Factors, (Kw) and (Kf)
• (a) Definition
• Soil erodibility factors (Kw) and (Kf) are
  erodibility factors which quantify the
  susceptibility of soil detachment by water.
• These erodibility factors predict the long-term
  average soil loss, which results from sheet and
  rill erosion under various alternative
  combinations of crop systems and conservation
  techniques. Factor Kw considers the whole soil,
  and factor Kf considers only the fine-earth
  fraction, which is the material lt2.0 mm in
  diameter. The procedure for determining the Kf
  factor is outlined in Agriculture Handbook No.
  703, Predicting Soil Erosion by Water A Guide to
  Conservation Planning with the Revised Universal
  Soil Loss Equation (RUSLE), USDA, ARS, 1997.

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Organic Matter

• Definition
• Organic matter percent is the weight of
  decomposed plant and animal residue and expressed
  as a weight percentage of the soil material less
  than 2 mm in diameter.

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T Factor (a) Definition

• The T factor is the soil loss tolerance. It is
  defined as the maximum amount of erosion at which
  the quality of a soil as a medium for plant
  growth can be maintained. This quality of the
  soil to be maintained is threefold in focus. It
  includes maintaining (1) the surface soil as a
  seedbed for plants, (2) the atmosphere-soil
  interface to allow the entry of air and water
  into the soil and still protect the underlying
  soil from wind and water erosion, and (3) the
  total soil volume as a reservoir for water and
  plant nutrients, which is preserved by minimizing
  soil loss. Erosion losses are estimated by USLE
  and RUSLE.

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• "T" CRITERIA 3/11/1995
• Soil Characteristic Definition
  Depth Limit (inches) T Value
• Bedrock A. Soils in all Land
  lt10 1
  Resource Regions except W, X, 10-20
  2
• and Y having SOFT identified 20-40
  3
• in the Bedrock soil
  property 40-60 4
• block or MARL (marl layers)
  gt60 5
• with the beginning depth of
  
• OR
• B. Soils having HARD identified lt20 1
• in the Bedrock soil
  property 20-40 2
• block or layers identified
  as 40-50 3
• ICE with the beginning depth of gt60
  5
• OR
• C. Soils in only Land

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Criteria used to determineT-Factor Classes

• Bedrock
• Cemented Pans
• Fragmental/Cindery
• Fragipan
• Natric
• Sandy or Sandy Skeletal Substratum
• Abrupt Textural Change
• Dense Layer
• Rock Fragments
• High Gypsum
• Organic
• High Carbonates
• Severely Eroded (can be used to adjust 1 class
  lower)

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T Factor Classes

• The classes of T factors are 1, 2, 3, 4, 5.

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• Hydrologic Group (618.35)
• (a) Definition
• Hydrologic group is a group of soils having
  similar runoff potential under similar storm and
  cover conditions.

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• (b) Classes
• The soils in the United States are placed into
  four groups, A, B, C, and D, and three dual
  classes, A/D, B/D, and C/D. In the definitions of
  the classes, infiltration rate is the rate at
  which water enters the soil at the surface and is
  controlled by the surface conditions.
  Transmission rate is the rate at which water
  moves in the soil and is controlled by soil
  properties. Definitions of the classes are as
  follows
• A. (Low runoff potential). The soils have a high
  infiltration rate even when thoroughly wetted.
  They chiefly consist of deep, well drained to
  excessively drained sands or gravels. They have a
  high rate of water transmission.
• B. The soils have a moderate infiltration rate
  when thoroughly wetted. They chiefly are
  moderately deep to deep, moderately well drained
  to well drained soils that have moderately fine
  to moderately coarse textures. They have a
  moderate rate of water transmission.
• C. The soils have a slow infiltration rate when
  thoroughly wetted. They chiefly have a layer that
  impedes downward movement of water or have
  moderately fine to fine texture. They have a slow
  rate of water transmission.
• D. (High runoff potential). The soils have a very
  slow infiltration rate when thoroughly wetted.
  They chiefly consist of clay soils that have a
  high swelling potential, soils that have a
  permanent high water table, soils that have a
  claypan or clay layer at or near the surface, and
  shallow soils over nearly impervious material.
  They have a very slow rate of water transmission.

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• Dual hydrologic groups, A/D, B/D, and C/D, are
  given for certain wet soils that can be
  adequately drained. The first letter applies to
  the drained condition, the second to the
  undrained. Only soils that are rated D in their
  natural condition are assigned to dual classes.
  Soils may be assigned to dual groups if drainage
  is feasible and practical.

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Pond Reservoir Area - Rule
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Soil Information System
Resource Data Gateway
eFOTG
Web Soil Surveys CARES Interactive Soil Surveys
Field Offices Soil Data Viewer
Spatial Data (Dig Units)
Soil Data Mart(s)
Soil Data Warehouse
Soil Staging Server
NASIS Transaction Database
Web Services/API
Pedon
LIMS
NRI
Models Applications -- RUSLE2, WinPST, WEPS,
etc
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