Nancy Rogel Eddie Guadarrama Soil Erosion Nancy Rogel Eddie Guadarrama

Outline What is Soil Erosion Types of Erosion Factors Affecting Erosion Rates Human Activities that increase Erosion Rates How to Prevent Erosion

What is Soil Erosion In agriculture, erosion refers to the removal of a field’s topsoil due to natural forces of water and wind or through human activities such as tillage 3 steps Soil detachment Movement Deposition

Types of Erosion Water Splash Sheet Rill Gully Bank Wind Suspension Saltation Soil Creep Glacial Plucking Abrasion Freeze-thaw

Water Erosion Splash Erosion: Direct movement of soil by the impact of water droplets. Soil particles can be thrown up to 3 feet Sheet Erosion: Uniform removal of soil in thin layers from a large area due to impact from raindrops Rill Erosion: Small channels (<30 cm) carved out on a slope by running water Gully Erosion: Large channels (>30 cm) carved out by running water that cannot be removed by normal tillage equipment Bank Erosion: Saturated sides of running streams fall into moving water below

Source: http://www.cep.unep.org/pubs/Techreports/tr41en/Image11.gif

Wind Erosion Suspension: The movement of fine particles into the atmosphere over long distances due to strong winds Saltation: The movement of soil particles through short bounces along the surface, displacing additional particles with each impact. Primary source of wind erosion. Soil Creep: The rolling of larger soil particles across the surface, aided by the bouncing movements of saltating particles

Source: http://passel. unl

Glacial Erosion Plucking:  Glacial ice freezes into cracks in rocks and when the glacier moves it pulls out rocks leaving a jagged surface Abrasion: When rock frozen to the base and the back of the glacier scrapes the bed rock Freeze-thaw: When water in the cracks of rocks freezes and expands. Over time, portions of rock are broken off

Factors Affecting Erosion Rates Climatic Factors Vegetation Characteristics of Soil Topography

Climatic Factors Rainfall Amount, Intensity and Frequency: A greater percentage of the rainfall will become runoff during periods of frequent rainfall. This is due to high soil moisture or saturated conditions.

Climatic Factors Temperature: Frozen soil is resistant to erosion Temperature affects organic matter

Vegetation Important physical factor influencing soil erosion. Vegetation binds the soil together which makes it more resistant to runoff. Organic matter is provided by vegetation which can slow down runoff. A dense, robust cover of vegetation is one of the best protections against soil erosion.

Characteristics of Soil Soil Texture: The size or combination of sizes of individual soil particles. Silt particles are most susceptible Clay or Sand particles are less prone to erosion.

Characteristics of Soil Soil Structure: Soil particles get clumped together to form larger clumps and pore spaces. Structure influences both the ability to absorb water and its resistance to erosion.

Topography Slope Length: Longer Slope Base of the slope Slope Steepness & Surface Roughness: Speed of runoff flow Erosion rates increase if the flow is fast.

Human Activities that Increase Erosion Rates Overgrazing Overcropping Deforestation Construction

Overgrazing Occurs when plants are exposed to intese grazing. Animals can damage the soil surface by eating the vegetation and compacting dry soil with their hooves. Soils with less vegetation become exposed and are more prone to water and wind erosion.

Overcropping This occurs when the land is being continuously cultivated with no breaks in between crops. Humus Production is affected The soil dries out and is prone for wind and rain erosion with less humus.

Deforestation Deforestation leaves an open and exposed landscape after cutting down large areas of forests. Nutrients and minerals are removed from the soil Areas are exposed to water and wind erosion.

Construction Construction often begins with by clearing the area of any plants or other natural defenses against soil erosion. Construction also includes several tasks such as altering drainage patterns and compacting the soil.

How to Prevent Erosion Terracing Contour Farming Cover crops A sloped plane is cut into a series of successively receding flat surfaces Contour Farming Planes of land are constructed by cutting off the land according to its contours. Cover crops Windbreaks Plant trees and shrubs along the edges of agricultural fields to help protect the fields against wind erosion. Mixed-cropping Crop rotation

Work Cited http://www.kalkaskacounty.net/planningeduc0043.asp http://en.wikipedia.org/wiki/Erosion#Factors_affecting_erosion_rates http://lcgeography.preswex.ie/how-human-activities-can-accelerate-soil-erosion.html http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0003/255153/fact-sheet-1-types-of-erosion.pdf http://passel.unl.edu/pages/informationmodule.php?idinformationmodule=1086025423&topicorder=19&maxto=7 http://www.geography.learnontheinternet.co.uk/topics/glaciation1.html