1 / 28

Capability Classes

Capability Classes. Capability Classes: Suited . Class I slight limitations Class II moderate limitations: restrict plants or require moderate conservation practices Class III severe limitations: restrict plants and/or require special conservation practices

sona
Download Presentation

Capability Classes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Capability Classes

  2. Capability Classes: Suited • Class I slight limitations • Class II moderate limitations: restrict plants or require moderate conservation practices • Class III severe limitations: restrict plants and/or require special conservation practices • Class IV soils have very severe limitations: restrict plants and/or require very careful management

  3. Capability Classes: Unsuited • Class V little or no erosion but have limitations use restricted to pasture, rangeland, forestland, or wildlife habitat • Class VI severe limitations generally unsuitable for cultivation and use restricted to pasture, rangeland, forestland, or wildlife habitat • Class VII very severe limitations unsuitable for cultivation and restrict use to rangeland, forestland, or wildlife habitat

  4. Capability Classes: Unsuited • Class VIII limitations that preclude commercial plant production and that restrict their use to recreational purposes, wildlife habitat, watershed, or esthetic purposes

  5. Subclasses • e – erosion risk • w – water/wetness • s – stony, droughty, shallow • c – cold or very dry

  6. Erosion - e • None, slight, moderate – no change • Severe – one class higher (2e to 3e) • Slope: • 0-2% - 1 (5) • 2-6%, 2-8% - 2e • 6-10%, 8-15%, 10-15% - 3e • 15-25% - 4e • 25-45% - 6e • 45+% - 7e

  7. Wetness - w Flooding • None-rare – class 1 • Occasional – class 2w • Frequent – class 3w

  8. Wetness - w Drainage Class • Well drained - 1 • Moderately well drained - 2w • Somewhat poorly - 2w • Somewhat poorly and clayey - 3w • Poorly drained - 4w • Very poorly drained and ponded - 6w • Tidal marsh - 7w

  9. Stony, droughty, shallow - s • Very stony: 2-15% slope - 4s • Very stony 15-45% slope - 6s • Extremely stony: 2-15% - 6s • Extremely stony: >15% - 7s • Depth shallow - 1-2 classes difference • Moderately deep (20-40”) if hard bedrock - 1 class difference

  10. Soil Erosionand Sediment Transport Adapted from R. McLaughlin and S. King, Soil Science Dept. NCSU

  11. Soil Erosion: Two Phases • Detachment: individual particles are loosened from the soil mass. • Rainsplash > running water > wind • Transport: water or wind carries the detached particles downslope or downwind. • Flow in rills is the most important.

  12. Raindrops: The Start of Erosion Rain droplet falls on saturated soil Crater formed Soil is displaced Displaced soil is deposited From Hillel 1998

  13. Soil is displaced Displaced soil is deposited, farther downslope than upslope Slope Makes Big Difference From Hillel 1998

  14. Overland Flow • Once rainfall exceeds infiltration, water begins to flow. • Clay is hard to pick up due to cohesion. • Sand is hard to pick up due to size. • Most of the sediment in sheet flow comes from rain detachment. • This is why covering the soil is so effective!

  15. Formation of Rills • Water begins to collect near the top of the slope. • Rills generally deepen downslope. • Flow itself results in erosion. • Headcutting moves upslope. • Sediment comes into the rill from overland flow.

  16. Overland vs. Rills • Studies have shown that both erosion processes are important. • Relative importance depends on soil, slope, and storm intensity. • Rills can carry large materials.

  17. Before Stabilization After Stabilization

  18. Gully Formation Overland or Rill Flow Nick or depression develops Headwall forms Scouring at headwall base Headwall retreats by undermining and collapse.

  19. Sediment Losses to System R. A. McLaughlin NCSU Soil Science

  20. Sedimentation: Size Matters Coarse Clay Silt Fine sand

  21. In-stream Damages May include: • destruction of spawning areas, food sources, habitat • toxicity to wildlife • lake degradation • siltation of navigation channels • impacts to commercial fisheries • reduction of water storage capacities Courtesy of CPESC, Inc.

  22. Erosion

  23. Tillage Effects Moderately eroded Uneroded Slightly eroded Severely eroded

  24. Turbidity • Turbidity is the measure of relative water clarity • Measured in NTU’s – Nephelometric Turbidity Units Photo from James G. Carver, Department of Geography and Geology, University of South Alabama

  25. Questions?

More Related