Soil Erosion Abbey Whelan Yu Jin Kim Period 3 Honors Biology

What is Soil Erosion?  When soil is naturally removed by the action of water or wind  Been occurring for 450 million years  Soil is removed at around the same rate that soil is formed  However, under conditions of ecological disequilibrium, this process is sped up

Why is it important?  It is important to prevent soil erosion because:  It results in the loss of nutrients in the soil  Makes it less productive for agricultural uses  Pollution of water by sediments and agricultural chemicals

Splash Erosion  First stage of the erosion process  Occurs when raindrop hits bare soil  Primary cause of soil detachment and disintegration  The impact breaks up soil particles so that they are “splashed” onto soil surface  The particles block space between soil aggregates (clumps)  Soil forms crust that increases runoff and reduces infiltration

Sheet Erosion  Loose particles of soil are moved downslope, commonly by sheet flooding  Results in an extensive loss of rich topsoil  Commonly occurs on recently plowed fields or other sites with poorly consolidates soil with scanty vegetative cover  Broad sheets of rapidly flowing water filled with sediment present a potentially high erosive force  Sheet floods are of brief durations and move short distances; usually produced by cloudbursts

Rill Erosion  Removal of soil by concentrated water running through little streamlets  Occurs when duration or intensity of rain increases and runoff volumes accelerate  Rills are the major sediment transport route for soil detached on inter-rill areas  Tillage makes soil more susceptible to rill erosion

Stream Channel Erosion  Consists of both stream bank and stream bed erosion  Stream bed erosion: water cuts into bottom of stream making it deeper until reaches slope  Sides of channel become soft and unstable causing it to slough off resulting in stream bank erosion  Stream bank erosion: occurs when soft materials are eroded from stream bank or at bends in channel  Result in meandering waterways  Both types of erosion caused by increased runoff due to urban development

Gully Erosion  Evolved form of channel erosion  When channel development has progressed to the point where the gully is too wide and too deep to be tilled across  These channels carry large amounts of water after rains and deposited eroded materials at the foot of the gully  Disfigure landscapes and make land unfit for growing crops

Tunnel Erosion  Occurs when surface water moves into and through dispersive subsoil (layer of soil underneath topsoil)  Dispersive soils are poorly structured; easily eroded when wet  Tunnel starts when water moves into soil along cracks or channels or through rabbit burrows and oil tree root cavities  Dispersive clays the first to be removed by water flow  As space enlarges, more water pours in causing more erosion  As tunnel expands, its roof collapses leading to potholes and gullies  Can be prevented by breaking open existing tunnels, re- vegetation, and increasing soil organic matter

Tillage Erosion  Moves soil from top of the field downward, exposing subsoil at the crest while burying soil at the bottom  After many years of tillage, topsoil accumulates at the bottom of the slope  No soil leaves the field due to tillage erosion  Effects for productivity and increased yield variability can be huge  Eliminate tillage to prevent this type of erosion

Prevention  Can be prevented by:  Planting a cover crop  Maintaining cereal stubbles  Maintaining organic matter  Reducing length of fallow periods  Reducing droplet size of irrigators

What society is doing to prevent soil erosion:  State of New Jersey passed the Soil Erosion and Sediment Control Act in 1975  “The Legislature finds that sediment is a source of pollution and that soil erosion continues to be a serious problem throughout the State.”  “It is, therefore, declared to be the policy of the State to strengthen and extend the present erosion and sediment control activities and programs of this State for both rural and urban lands…to reduce the danger from storm water runoff, to retard nonpoint pollution from sediment and to conserve and protect the land, water, air and other environmental resources of the State.”  Similar programs were enacted in Michigan and Maryland

Contacts  California Environmental Protection Agency  Information Hotline: (202)  Secretary for Environmental Protection P.O. Box 2815 Sacramento, CA  US Department of Agriculture  General Public Contact: (916)  U.S. Department of Agriculture 1400 Independence Ave., S.W. Washington, DC 20250

Work Cited "Contact Us." Cal/EPA. N.p., n.d. Web. 25 Feb "Contact Us." U.S. Department of Agriculture. N.p., n.d. Web. 23 Feb "Gullies." The National Soil Erosion Research Laboratory. N.p., n.d. Web. 24 Feb "Rill Erosion." The National Soil Erosion Research Laboratory. N.p., n.d. Web. 24 Feb "Soil Erosion and Sediment Control Act." Department of Agriculture. State of New Jersey, n.d. Web. 25 Feb "Splash Erosion (Rain Drop Impact)." DPIPWE. N.p., n.d. Web. 24 Feb The Editors of Encyclopædia Britannica. "Sheet Erosion (geology)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 24 Feb "Types of Soil Erosion." Freie Universität Berlin. N.p., n.d. Web. 23 Feb