Chapter 10 Soil Erosion, Leaching, and Pollution Chapter Outcomes • Explain ways that soil degrades in the environment. • Discuss how compaction degrades soil. • Identify factors that contribute to soil erosion. • Discuss how leaching degrades soil. • Discuss how pollution degrades soil and ways in which it can be prevented. Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Essential Question • Why is it crucial to understand the effects of our actions on the environment? Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Soil Degradation • Reduction of soil productivity • Caused by human or natural causes • Results from compaction, erosion, leaching, pollution • Soil often cannot be fully restored (Andriy Solovyov/Shutterstock.com; Scharfsinn/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Soil Compaction • Crushing of pore spaces • Commonly caused by heavy tractors • Example: well-traveled dirt road • Prevents plant growth • More severe with wet and clayey soils • Reversed with subsoil ripper (Ruud Morijn Photographer/Shutterstock.com; rsooll/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. The Effect of Soil Compaction on Plant Growth (Amanita Silvicora/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Sports Fields Soil Compaction on the Grid Iron • First 25 yards in front of goal posts • Most used part of football field • Middle of field near end zones • Can become harder than gymnasium floor • National Football League • Regulates soil density in stadiums (Telnov Oleksii/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Soil Erosion • Removal and displacement of top layer • Natural process • Caused primarily by wind & water • Bare soils, tilled fields highly susceptible • Relocated soil less productive (Thongsuk Atwannakul/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. History Connection The Dust Bowl • Affected Great Plains in 1930s • Rainfall abundant in 1920s • Farming increased; prairie grasses plowed • Severe drought in 1931 • Soil became dry, was blown away • Dust traveled to east coast (Everett Historical Society/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Wind Erosion and Water Erosion • Wind erosion • Creates dust and dust storms • Occurs most frequently in arid regions • Water erosion • More common on most land • Water capable of moving tons of soil Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Soil Infiltration and Percolation • Soil infiltration • Water movement into, through soil profile • Percolation • Water movement within soil profile • Quick infiltration and percolation—little erosion • Water remains at/near surface—erosion occurs Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Soil Infiltration and Percolation (Amanita Silvicora/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. The Four Stages of Water Erosion • Splash • Sheet • Rill • Gully erosion Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Splash Erosion • Raindrops breaking soil aggregates apart • Soil not moved a significant distance Amanita Silvicora/Shutterstock.com Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Sheet Erosion • Occurs when water: • Accumulates on soil’s surface • Pools and flows over surface • Fairly uniform removal of soil • Typically occurs at tolerable levels • Remedied with general tillage operations (USDA NRCS) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Rill Erosion • Occurs when water: • Carries soil particles • Carves out small channels • Soil tillage • Removes signs of rill erosion • May not remedy problem (Jordi Roy/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Gully Erosion • Occurs when rills combine • Water flow carves gully deeper, wider • Carries sediment to ditches, streams • Most detrimental type of water erosion • Results in most soil loss • Difficult and expensive to remedy (Hodyachaya Alla/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Soil Erodibility • Sensitivity of soil to effects of wind, water • Erodibility index (EI) • Numerical value representing erosion potential • Highly erodible land (HEL) • Most susceptible to erosion • Erodibility index greater than 8 Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Soil Erodibility Index (USDA NRCS) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. STEM Connection: Erosion Control • Cut three plastic bottles as shown; glue to plywood • Cover first with soil, second and third with soil/compost mix • Install plants in third bottle • Cut three bottles in half horizontally • Hang from necks of first three bottles • Pour water in first three bottles • Observe color as water fills bottle bottoms (Goodheart-Willcox Publisher) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Shoreline Erosion • Removes soil from lake/pond bank • Coastal or beach erosion • Shoreline erosion at ocean coastline • Wave action erodes soil, rocks • Also caused by gully erosion (tamara321/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Channel Erosion • Removal of stream/riverbanks or beds • Evenly distributed in healthy waterways • Excessive force or volume of water: • Banks can collapse. • Ecosystems can be destroyed. • Water can become polluted. Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Streambank Erosion • Streambank soil erodes, deposits in channel • Outgrowth of channel erosion • May occur gradually or suddenly • Potentially detrimental to stream/ocean ecosystems (Jason Patrick Ross/Shutterstock.com; astudio/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Factors that Contribute to Soil Erosion • Natural factors • Climate, soil structure • Vegetative cover, topography • Human activities • Construction, forestry practices (Kochneva Tetyana/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Climate and Soil Structure • Greater erosion likely in: • Climates with more precipitation • Areas that experience intense rainstorms • Soil structure • Weak soil structure allows greater penetration • Stronger soil structure resists water flow Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Vegetative Cover • Protects soil from erosion • Breaks fall of raindrops • Absorbs water into root system • Roots and root hairs also: • Hold soil particles in place • Prevent their movement on sloped landforms Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Topography • Surface configuration or land area features • Includes slope (rise or fall) • Greater kinetic energy of water moving down: • Steep slopes • Long slopes • Steeper, longer slopes more susceptible to erosion Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Construction • Creates vulnerable soil erosion situation • Erosion control regulations in many municipalities • Silt fences • Short mesh fabric fences • Allow water flow but trap sediment • Help prevent water contamination (Darryl Brooks/Shutterstock.com; Steven Frame/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Forestry • Removes vegetative cover • Leaves land vulnerable to erosion • Equipment often heavy, uses same trails • Compacts soil • Creates low places that collect water • Hilly areas highly susceptible to erosion (wwwarjag/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Leaching • Loss of minerals due to: • Rain • Irrigation • Nutrients move below root zone • May eventually contaminate groundwater (Jacky Co/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Groundwater Contamination • Special concern around: • Garbage dumps, landfills, feedlots • Areas of high pesticide, fertilizer applications • Eutrophication • Water becomes enriched with excess nutrients • Rapid plant growth depletes dissolved oxygen (BLUR LIFE 1975/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Soil Pollutants • Industrial waste • Agricultural chemicals • Improperly disposed household, consumer products • Small plastic particles Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Industrial Waste • Buried, dumped before stricter regulations enacted • Common industrial contaminants: • Waste from mining operations • Fuels from spills, leaking containers • Heavy metals from mining, manufacturing processes • De-icing chemicals used on roads Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Mining Operations • Overburden • Soil, rocks covering coal or ore veins • Piled near mine • Destroys topsoil • Leaches chemicals into groundwater • Used today to contour, revegetate landscape (Mikadun/Shutterstock.com; Mikadun/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Fuel Storage • Fuel tanks often located underground • Leaking common with older installations • Contaminates soil • May leach into groundwater sources • Difficult, expensive to remedy • Polymer tanks, secondary barrier now required Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Heavy Metals • Lead, mercury, arsenic, copper, zinc, nickel • Originate from: • Mining, manufacturing, foundry activities • Nearly impossible to cleanse contaminated soil • Even very small amounts are toxic • Recycling, concrete vaults now required Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Deicing Chemicals • Used in snow, ice removal • Washed into surrounding land, streams, rivers • Toxic to animals, plants • Can create health problems for humans • Today’s materials organic, degrade quickly • Reduced need with better weather forecasting (Patrick Jennings/Shutterstock.com) Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Agricultural Pesticides and Fertilizers • In the past, farmers would: • Apply fertilizers, pesticides across fields • Dump excess on ground or driveway • Modern precision technologies allow: • More precise applications • Minimal waste Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Household and Consumer Waste • Examples: • Soaps, bleach, and other cleaning agents • Oil, fuel for vehicles • Batteries, paints, varnishes, medications • Must use, dispose of chemicals properly • Utilize electronics, battery recycling Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Reducing Household and Consumer Waste • Purchase/make environmentally friendly cleaning agents • Use organic garden, pest control methods • Purchase only amount of pesticides, fertilizers needed • Offer leftovers for neighbor’s garden • Use pesticides, fertilizers sparingly • Recycle used motor oil; do not dump Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website. Reducing Household and Consumer Waste • Use rechargeable batteries, recycle old batteries • Wash paintbrushes in utility sink • Do not wash on lawn, driveway • Utilize municipal, business programs for: • Recycling leftover paint • Disposing of unneeded medications Copyright Goodheart-Willcox Co., Inc. May not be posted to a publicly accessible website.
