5 Soil Erosion (Non Test)

A set of 70 vocabulary flashcards covering the causes, mechanics, measurements, and global impacts of soil erosion as discussed in the lecture.

Soil Erosion

The removal of material from one place and its transport to somewhere else.

Natural vs. Anthropogenic Erosion Rate

Intensive farming and vegetation removal make human-influenced erosion $10\times$ more influential than all natural processes combined.

Global Soil Erosion Estimate (2012)

Approximately $36$ picograms ($10^9$ megagrams) of soil are eroded across the planet every year.

Erosion Rate in South America, Asia, and Africa

Approximately $3.5$ tons (milligrams) per hectare per year.

Erosion Rate in North America

Approximately $2.2$ milligrams per hectare per year.

Erosion Rate in Europe

Approximately $0.9$ milligrams per hectare per year.

Carbon Loss via Erosion

An estimated $0.3$ to $1$ picograms of carbon is lost annually from soil organic carbon.

Aviation Carbon Production

$190$ milligrams of carbon per year.

Conservation Tillage

A land management practice that results in great declines in soil erosion compared to traditional methods.

Deposition

The arrival of eroded material at a new location.

Colluviation

The natural process of moving material from one place to another, which can help build fertile soil.

Causes of Accelerated Erosion

Plowing, over-cultivating, overgrazing, deforestation, forest fires, and urbanization.

Splash Erosion

Erosion caused by the kinetic energy of a water drop hitting the soil.

Sheet Erosion

Erosion occurring when water flows over the soil surface in a nice thin sheet.

Rill Erosion

Erosion occurring when surface water flows faster and more turbulently than in sheet erosion.

Gully Erosion

A devastating form of water erosion caused by high-velocity surface flow.

Soil Cohesion

A factor influencing erosion based on how well soil particles, particularly clays, bind together.

Precipitation Factors

Erosion is influenced by both the total amount and the intensity of rainfall.

Vegetation Interception

The process where leaves absorb rain splash energy and water drips off slowly to the ground.

Root Reinforcement

The process by which plant roots bind soil together and increase structural stability.

Slope Steepness

A topographic factor where water flows more quickly on steeper landscapes, increasing erosion.

Soil Texture

The size of soil particles (clay, silt, sand) which determines how easily they are picked up or moved.

Clay Particle Size

Soil particles smaller than $2$ microns.

Silt Particle Size

Soil particles between $2$ microns and either $50$ or $63$ microns.

Sand Particle Size

Large soil particles that are generally not picked up by water due to ihre weight.

Erodibility of Silt

Highly erodible because it easily goes into suspension in overflowing water.

Erodibility of Clay

Less erodible unless dispersed because the particles stick together and require high flow velocity to move.

Soil Aggregates

Small particles clumped into bigger structures that withstand erosion better than individual particles.

Aggregate Explosion

A process where air pressure builds up inside dry aggregates as they wet quickly, causing them to disperse.

Hypothesis on Nitrogen and Erosion

Soils with no added nitrogen may have less fungi/plant growth, causing quicker water infiltration and higher erosion risk.

100-Year Storm Event

A prediction tool for erosion based on rare but short and very intensive rainfall (e.g., $60$ millimeters in an hour).

Surface Roughness

An erosion-reducing property increased by the presence of vegetation stems.

Root Area Ratio

The area of roots over the total area of the soil, influencing the detachment rate of soil particles.

Topography Factors

Slope steepness, slope length, slope shape (curvature), and aspect.

Slope Length and Erosivity

The longer the slope, the greater the erosive power as the depth of flowing water increases downstream.

Planar vs. Convergent Slopes

Planar slopes have sheet flow; convergent slopes concentrate flow in the center, accentuating erosion.

Slope Aspect

The direction a slope faces (e.g., southerly), which affects vegetation growth and soil formation.

RUSLE

The Revised Universal Soil Loss Equation, used for modeling and predicting soil loss.

RUSLE Factor A

The calculated soil loss measured in tons per hectare per year.

RUSLE Factor R

The rainfall-erosivity factor based on intensity and duration.

RUSLE Factor K

The soil erodibility factor based on physical soil properties.

RUSLE Factor L

The slope length factor.

RUSLE Factor S

The slope steepness factor.

RUSLE Factor C

The cover-management factor, representing vegetation or compost treatments.

RUSLE Factor P

The support practice factor for erosion control measures.

Compost Application Effect

Applying $300$ tons per hectare of compost significantly reduces soil loss and runoff.

Hydraulic Conductivity

The speed at which water enters the soil; increased by plant growth and compost.

Bounded Plot

A soil erosion measurement system where a plot is enclosed to collect water and sediment samples.

Rainfall Simulator

A device that applies water as controlled drops at specific rates and heights to measure erosion in the field.

Erosion Pin

A low-tech tool inserted deep into the soil to measure how much surface soil has been lost over time.

Cesium-137 ($^{137}Cs$)

A radioactive isotope from nuclear testing used as a tracer to measure soil movement and erosion.

Cesium Ionic Radius

A very small radius that allows it to adsorb readily to soil particles, particularly at the surface.

Chernobyl Fallout in Norway

Radioactive cesium deposited on lichen led to high doses in grazing reindeer.

Cesium Deposition Trend

Increased through nuclear testing in the $1960s$ and is now decreasing due to its half-life.

Cesium in Loess Plateau Slopes

Lower concentrations are found in eroding middle-slope sections, while higher concentrations exist in deposition zones.

Cosmogenic Radionuclides

Radioactive isotopes like Beryllium-$10$ ($^{10}Be$) used to describe rock weathering and surface erosion.

Beryllium Deposition

Naturally deposited on the earth's surface continuously through meteorites.

Isotopic Signature ($^{10}Be/^{9}Be$)

The ratio of meteorite-derived Beryllium-$10$ to old bedrock Beryllium-$9$ used to track soil history.

Soil Formation Rate (Arable)

Approximately $0.048$ millimeters per year.

Soil Formation Rate (Forest)

Approximately $0.07$ millimeters per year.

A-Horizon Lifespan Prediction

On certain arable soils, the A-horizon is estimated to last $260$ to $270$ years.

Wind Erosion

The transport of soil particles by wind through creep, saltation, and suspension.

Surface Creep

The movement of large minerals as they roll or slide along the soil surface during wind erosion.

Saltation

The 'leapfrogging' movement of particles between $0.1$ and $0.5$ millimeters in size.

Suspension (Aerosol)

Particles smaller than $0.1$ millimeter that are lifted high and travel thousands of miles.

Wind Tunnel

A device used for measuring wind erosion using fans, optics, and lasers to track particle movement.

Mycorrhizal Fungi Impact

High levels of fungi lead to less wind erosion because hyphae and exudates bind soil particles together.

The Great Dust Bowl

A devastating social and ecological disaster in the US Midwest caused by drought and the loss of native prairie vegetation.

The Grapes of Wrath

A book by John Steinbeck that depicts the plight of people displaced by the Great Dust Bowl.

Franklin Delano Roosevelt Quote

'The nation that destroys its soil destroys itself.'