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Earth’s Surface: Chapter 4 Section 3 Human Activities Affect Soil

Earth’s Surface: Chapter 4 Section 3 Human Activities Affect Soil. Learning Targets: 1) I can explain why soil is a necessary resource 2) I can describe how soil is affected by people 3) I can demonstrate how to conserve soil. Soil is a Necessary Resource.

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Earth’s Surface: Chapter 4 Section 3 Human Activities Affect Soil

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  1. Earth’s Surface: Chapter 4 Section 3 Human Activities Affect Soil • Learning Targets: • 1) I can explain why soil is a necessary resource • 2) I can describe how soil is affected by people • 3) I can demonstrate how to conserve soil

  2. Soil is a Necessary Resource • Soil helps to sustain life on Earth • Soil supports the growth of plants which in turn supply food for animals. • Therefore, soil provides nearly all the food you eat • Plants provide us with cotton for clothing, medicines, lumber, and the oxygen we breathe • Soil helps purify water as it drains through the ground • Soil provides a home for a variety of living things

  3. Land-Use Practices Can Harm Soil • Any activity that exposes soil to wind and rain can lead to soil loss • There are 3 main activities that affect soil resources • 1) Farming • 2) Construction and Development • 3) Mining

  4. Farming • Farming is very important to society, however it can have some harmful effects and lead to soil loss. • Some fertilizers can make it difficult for microorganisms in the soil to produce nutrients • Fertilizers also add to water pollution when rainwater drains from the fields and carries the excess nutrients to river, lakes and oceans

  5. Farming • Some farming practices can also lead to soil loss • Farmers clear trees and other plants and plow up the soil to plant crops • The soil is more exposed to rain and wind and is more likely to get washed or blown away. • American farmers lose about 5 metric tons of soil for each metric ton of grain they produce • In other parts of the world, the losses are higher

  6. Farming - Overgrazing • Overgrazing can be another problem • Overgrazing occurs when farm animals eat large amounts of land cover • Overgrazing destroys natural vegetation and can cause the soil to be washed or blown away more easily. • Overgrazing and the clearing of land in some parts of the world (dry) for farming has led to desertification • Desertification is the expansion of desert conditions in areas where the natural plant cover has been destroyed

  7. Construction and Development • As people build, roads, houses, malls, and other buildings plants the ___________ are dug up • Some of it washes or blows away because its protective cover has been removed. • The soil can end up in low lying areas, rivers, streams, lakes or reservoirs • It can make the rivers and lakes muddy and harm the organisms that live there • It can raise the level of water and cause flooding

  8. Mining • Strip mining and open pit mining involves the removal of plants and soil which causes soil loss • By exposing the rocks and minerals to the air and to rainwater, it speeds up the rate of chemical weathering • Which can cause a type of pollution known as acid drainage • Abandoned mines can fill with rainwater • Sulfide minerals react with air and water to produce sulfuric acid • The acid water drains from the mines, polluting the nearby areas.

  9. Soil Conservation • Soil conservation is important, because it can be difficult or impossible to replace • A soil with well developed horizons can take hundreds to thousands of years to form • The following are soil conservation methods • 1) Crop Rotation • 2) Conservation Tillage • 3) Terraces • 4) Contour Plowing • 5) Windbreaks

  10. Crop Rotation • Crop rotation is a process of growing different crops on the same field in different years. • Grain crops, such as wheat, use up a lot of nitrogen • Bean crops, such as soybeans restore nitrogen to the soil • By rotating these crops, farmers can help maintain soil fertility.

  11. CROP ROTATION

  12. CROP ROTATION

  13. Conservation Tillage • Conservation tillage is a method that reduces the number of times fields are plowed in a year. • The less soil is disturbed by plowing, the less likely it is to be washed or blown away. • In one method of conservation tillage, fields are not plowed at all • This is called no till farming.

  14. NO TILL FARMING

  15. NO TILL FARMING

  16. Terraces • Terraces are flat, steplike areas built on a hillside to hold rainwater and prevent it from running downhill • Crops are planted on the flat tops of the terraces.

  17. TERRACING

  18. Contour Plowing • Contour plowing is the practice of plowing along the curves or contours of a slope • It helps channel rainwater so that it does not run straight downhill, carrying away soil with it. • Strip cropping is often combined with contour plowing. • Strips of grasses, shrubs or other plants are planted between bands of a grain crop along the curve of a slope. • These strips of plants also help slow the runoff of water.

  19. CONTOUR PLOWING

  20. Windbreaks • Windbreaks are rows of trees planted between fields to “break,” or reduce, the force of winds that carry off soil

  21. WINDBREAKS

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