NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Capability Classes

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 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

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 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

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 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

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Subclasses e – erosion risk w – water/wetness s – stony, droughty, shallow c – cold or very dry

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 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

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Wetness - w Flooding None-rare – class 1 Occasional – class 2w Frequent – class 3w

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 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

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 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 classes difference Moderately deep (20-40”) if hard bedrock - 1 class difference

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Soil Erosion and Sediment Transport Adapted from R. McLaughlin and S. King, Soil Science Dept. NCSU

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 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.

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Raindrops: The Start of Erosion From Hillel 1998 Crater formed Soil is displaced Displaced soil is deposited Rain droplet falls on saturated soil

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Slope Makes Big Difference From Hillel 1998 Soil is displaced Displaced soil is deposited, farther downslope than upslope

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 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!

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 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.

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 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.

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Before Stabilization After Stabilization

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Gully Formation Overland or Rill Flow Nick or depression develops Headwall forms Scouring at headwall base Headwall retreats by undermining and collapse.

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Sediment Losses to System NCSU Soil ScienceR. A. McLaughlin

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Sedimentation: Size Matters Fine sand Silt Coarse Clay

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE In-stream Damages 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. May include:

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Erosion

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Tillage Effects Uneroded Slightly eroded Severely eroded Moderately eroded

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE 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

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE Questions?

NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE NC STATE UNIVERSITY DEPARTMENT of SOIL SCIENCE