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About Nez Perce SWCD

About Us
District History
District Board
   ▸ Meeting Schedule and Agendas
       ▸ January 21, 2020
       ▸ March 19, 2020
       ▸ April 1, 2020
       ▸ May 21, 2020
       ▸ Archived Meeting Agendas
   ▸ Supervisors Past and Present
   ▸ Information for Board Supervisors
General Conservation History
Natural Resource Inventory
   ▸ Executive Summary
   ▸ Abbreviations and Symbols
   ▸ Economic Conditions and Trends
   ▸ Physical Characteristics
       ▸ Physical Inventory
           ▸ Soils and K-Factor
           ▸ Water Resources and Wetlands
           ▸ Climate and Air Resources
           ▸ Ownership
           ▸ Plant Resources
           ▸ Animal Resources
           ▸ Land Use Management
           ▸ Common Resource Area
      ▸ Resource Conditions and Trends
  ▸ Contact Us
  ▸ Employment
  ▸ Partners
  ▸ Public Comment
  ▸ IASCD

Soils

Soils develop as a result of climate, living organism, and landscape position interactions as they influence parent material decomposition over time. Parent material refers to the organic and mineral material in which soil is formed. Mineral materials include rock, volcanic ash and sediment. The types of parent materials found in the District include basalt, ash, and sediments.

Climate also contributes to soil formation by determining the amount of water available for weathering minerals and transporting the materials. Canyon soils have weathered rock parent material. These soils are typically rocky and shallow. The Palouse prairie has thick deposits of Palouse loess (windblown soil) as the parent material. These soils are typically deep, silty and intensively used for agriculture. Figure S is a general soils map for the county.

Soil surveys identify the characteristics to determine the limitations and qualities of soils for all land uses. Interpretations are designed to warn of possible soil-related hazards in an area.

Figure S. Nez Perce County General Soils Map.

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LEGEND - General Soil Map

Lewis and Nez Perce Counties, Idaho

Nearly level to steep, medium and moderately coarse textured soils on terraces and valley floors.
A3Pleasant View-Tom Beall: Nearly level to undulating, very deep, well drained and somewhat poorly drained soils that formed in alluvium.
A5Chard-Tammany: Undulating to steep, very deep, well drained soils that formed in alluvium.
Undulating to hilly, fine to medium textured soils on plateaus.
B1Naff-Palouse-Thatuna: Very deep, well-drained and moderately well drained, warm soils that formed in loess.
B2Taney-Setters-Carlinton: Moderately deep to fragipan and very deep, moderately well drained, cool soils that formed in loess.
B3Craigmont-Culdesac: Deep and very deep, well drained, cool soils that formed in loess, volcanic ash, and material weathered from basalt.
B4Uhlorn-Nez Perce: Very deep, well drained and moderately well drained, warm soils with a high content of organic matter in the surface layer that formed in loess.
B5Broadax-Oliphant-Hatwai: Very deep, well drained, warm soils with secondary carbonates in the subsoil that formed in loess.
B6Boles-Joel: Very deep, moderately well drained and well drained, cool soils that formed in loess.
B7Southwick-Driscoll-Larkin: Moderately deep to fragipan and very deep, moderately well drained and well-drained, warm soils that formed in loess.
B8Johnson-Kruse: Very deep, well drained, cool soils that formed in loess and granitic colluvium.
Hilly to very steep, fine to moderately coarse textured soils on canyon slopes.
C1Lickskillet-Alpowa-Crowers: Shallow and very deep, well-drained medium textured, warm soils with secondary carbonates in the subsoil that formed in basalt colluvium.
C2Kettenbach-Linville-Gwin: Moderately deep, very deep and shallow, well drained, moderately fine and medium textured, warm soils that formed in basalt colluvium.
C3Webbridge-Agatha: Deep, well drained, moderately fine textured, cool soils that formed in volcanic ash and material weathered from basalt.
C4Klickson-Bluesprin-Riggins: Very deep, moderately deep, and shallow, well drained moderately fine textured, cool and warm soils that formed in basalt colluvium.
C6Johnson-Spokane: Very deep and moderately deep, well drained, moderately fine and moderately coarse textured, cool and warm soils that formed in granitic colluvium and alluvium.
C7Keuterville-Kettenbach-Jacket: Moderately deep and very deep, well drained, moderately fine textured and fine textured warm soils that formed in loess and basalt colluvium.

K Factor

K factor is soil erodibility factor which represents both susceptibility of soil to erosion and the rate of runoff, as measured under the standard unit plot condition. Soils high in clay have low K values, about 0.05 to 0.15, because they resistant to detachment. Coarse textured soils, such as sandy soils, have low K values, about 0.05 to 0.2, because of low runoff even though these soils are easily detached. Medium textured soils, such as the silt loam soils, have a moderate K values, about 0.25 to 0.4, because they are moderately susceptible to detachment and they produce moderate runoff. Soils having a high silt content are most erodible of all soils. They are easily detached; tend to crust and produce high rates of runoff. Values of K for these soils tend to be greater than 0.4.

Organic matter reduces erodibility because it reduces the susceptibility of the soil to detachment, and it increases infiltration, which reduce runoff and thus erosion.

Soil structure affects both susceptibility to detachment and infiltration. Permeability of the soil profile affects K because it affects runoff.

Although a K factor was selected to represent a soil in its natural condition, past management or misuse of a soil by intensive cropping can increase a soil's erodibility. The K factor may need to be increased if the subsoil is exposed or where the organic matter has been depleted, the soil's structure destroyed or soil compaction has reduced permeability.

Table KF. Nez Perce County K factor rating

% of soil with K factor >.37Acres of soils with K factor >.37Total Acres in County
46%254,258547,252

Figure KF. Soils with > 0.37 K factor.

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