DOC PREVIEW
UT Knoxville ESS 120 - Soil Erosion
Type Lecture Note
Pages 5

This preview shows page 1-2 out of 5 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 5 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 5 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 5 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

ESS 120 1st Edition Lecture 7Outline of Last Lecture I. Less Protein Consumption= Less Corn ProductionA. Consider Supply/DemandII. Speaking to PolicymakersA. Write a letter or EmailB. Phone CallOutline of Current Lecture III. Soil ErosionA. Land Degradation and LossIV. On Site Effectsa. Soil ProductivityV. Off Site Effectsa. SedimentsVI. Soil Loss Tolerancea. T-ValueVII. Erosion Processa. AcceleratedVIII. Types of Erosiona. WaterThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.b. Windc. Gravitational Erosiond. Splash Erosione. Surface Erosionf. Channel ErosionIX. Soil CharacteristicsX. Slope CharacteristicsXI. How to Stop ErosionXII. Predicting Soil Erosiona. RUSLECurrent LectureSoil Erosion- Geologically, always occurring- Accelerated, due to humans, animals- Tillage/plowing for agriculture, accelerates erosionThe Problem:1) Land Degradation and loss2) Urbanization3) DeforestationDecline in cropland- 50% since 1960.Decline in topsoil, past 30 years the rate of soil loss in Africa has increased 20-fold.On-site effects: Soil Productivity1) Reduction in topsoil depth2) Reduced rooting zone3) Lower nutrient and water holding4) Loss of fine fraction, silts, clays“Nothing is more vital to good soil management than providing for the regular and systematic return of organic matter to the soil” – Soils and Men.Off-Site Effects: Sediments1) Yellow River- China2) Ganges River- India3) Mississippi River- USa. Best soils in the US and WORLD.Effects of SedimentsSediments are no 1 pollutant of surface water1) Water quality2) Nutrients, eutrophication3) Pesticides4) Soil fines carry these into water5) Aquatic habitat destruction6) Spawning grounds covered7) Lower photosynthesis = less oxygen (Hypoxy)8) Filling waterways, reservoirs9) Flooding10) Dredging costs >300 mil per yr in USWater supply degradation1) Must remove sediment2) Very expensiveMagnitude of the problem:1) Croplands2) Poor forest management3) Poor pasture/over grazing4) Urban construction**HUMANS CAN DESTROY ONE INCH OF SOIL IN LESS THAN A YR.Soil Loss Tolerance= T ValueT= max rate of annual soil loss that will permit crop productivity to occur economically and indefinitely.- 2-5 t/ac/yr for most soils- THIS IS TOO HIGH FOR MOST SOILS- Loess (silty) soils erode the easiest.EROSION PROCESS- Erosion- movement of soil from desirable to undesirable location.1) detachment2) Transport3) DepositionGeologic vs accelerated erosion- Erosion is always occurring- Disturbing of soil causes accelerated- Farming, construction, etc.Types of Erosion1) Water2) Removal of soil or rock by moving water3) WindBy wind- Gravitational Erosion- LandslidesSplash Erosion - Impact of raindrop detaches silt and sand particles- Tremendous transfer of energy to soil- Destroys aggregatesSurface Runoff or Sheet Erosion- TRANSPORT of detached particles- Clays and Silts travel further, sand travel the leastInternal Erosion- washing of soil particles into cracks and pores- Reduces infiltration, also called CRUSTING or SUFACE SEALINGChannel Erosion- 1) Rills2) Gullies3) streambank erosion Factors affecting water erosion- Rainfall characteristics; Frequency, intensity and duration of rain; as these increase total energy available for erosion increases- Soil Characteristics1) Texture2) Structure3) Organic matter content4) Permeability5) Slope CharacteristicsAs length and % slope increase, amount and velocity of runoff increases, so erosion increasesVegetative cover- Residues protect against SPLASH EROSION, slows runoff velocity, so TRANSPORT decreases - Builds Organic Matter and soil aggregationHow to stop erosion:- Erosion prevention is easier than stopping it once it starts1) surface residues must be maintained2) reduce tillage passes3) increase organic matter contents4) produce enough biomass for erosion controlPrediction of soil erosion by water- RUSLE- Revised universal soil loss equation- Predicts loss as function - A = R*K*LS*C*P A = annual soil loss from sheet and rill erosion in tons/acre R = rainfall erosivity factorK = soil erodibility factorLS = slope length and steepness factorC = cover and management factorP = support practice factor- Major changes to the USLE incorporated into RUSLE include: R factor: new and improved isoerodent maps and erodibility index (EI) distributions for some areasK factor: time-variant soil erodibility which reflects freeze-thaw in some geographic areasLS factor: new equations to account for slope length and steepnessC factor: additional sub-factors for evaluating the cover and management factor for cropland and rangeland P factor: new conservation practice values for cropland and


View Full Document

UT Knoxville ESS 120 - Soil Erosion

Type: Lecture Note
Pages: 5
Download Soil Erosion
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Soil Erosion and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Soil Erosion 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?