Soil Erosion PS U6 L9

Bird City, Kansas

St. Francis, Kansas

San Luis Valley, Colorado

Al Asad, Iraq

The Dustbowl

How much soil is lost? 5 Billion Tons, Billion with a “B” lost each year 3.5 Billion tons due to Water 1.5 Billion tons due to Wind

What is average loss? Scientists expect to lose 5 tons per acre per year This much can be re-captured through soil formation Water makes up 4.8 tons lost Wind makes up 3.3 tons lost 8.1 tons is average THIS IS TOO MUCH!

Lasting effects of erosion Loss of topsoil-loss of productive organisms Organic matter gone along with N-P-K Reduced Root Zone-less water holding capacity Gullies make farming difficult Pollutes lakes, streams causing harm to wildlife Sediment fills up lakes, streams, and waterways Loss of $$$$ due to un-productive soil Sediment fills and pollutes a lake

What affects erosion #1 Texture and Structure The coarser the texture, the higher infiltration rate, the lower amounts of run-off Fine particles detach easier than large particles Silt erodes faster than sand Good structures resist rain splash and wind lift

What affects erosion #2 Slope Length and steepness or grade both need considered Length accounts for volume of erosion Grade creates water velocity Long fields have snowball effect with wind Little loss at the head end, piles of soil at the bottom end

What affects erosion #3 Surface Roughness Rough soil slows water and reduces downhill flow Tillage ridges are helpful Tillage across slope prevents erosion, tillage with the slope promotes erosion

What affects erosion #4 Surface Cover Surface cover reduces impact from falling water and slows down movement of water Surface crops’ roots hold soil closely Row crops need a foliage canopy to help protect soil

What affects erosion #5 Climate Dry soils and dry climates promote wind erosion The drier the soil particles the greater risk of being picked up and moved elsewhere Dry weather promotes wind loss

Types of erosion #1 Splash Erosion Water hits the soil and can move particles as much as 5 feet!

Types of erosion #2 Sheet erosion A thin layer of soil is removed as a sheet. Sheet erosion hides until topsoil is lost and subsoil is exposed. Sheet erosion exposes sub-soil in the circles

Types of erosion #3 Rill erosion Many small channels on slopes Running water carves out rills Still can be filled in by tillage

Types of erosion #4 Ephemeral (e fem er al) Large rills Tillage won’t completely fill them in The next rain will create gullies if not fixed

Types of erosion #5 Gully erosion So large equipment cannot cross Begin on steep slopes where water creates enough energy to cut large channels in the earth