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Earth’s Resources

Earth’s Resources. Chapter Fifteen: Soil and Fresh Water Resources. 15.1 Soil 15.2 Water Resources. Investigation 15A. Natural Resources. What resources do we use and how can we conserve them?. 15.1 What is soil?.

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Earth’s Resources

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  1. Earth’s Resources

  2. Chapter Fifteen: Soil and Fresh Water Resources • 15.1 Soil • 15.2 Water Resources

  3. Investigation 15A Natural Resources • What resources do we use and how can we conserve them?

  4. 15.1 What is soil? • In nature, humusrefers to the material that is produced by the bacterial decay of plant and animal matter, also known as organic matter.

  5. 15.1 What is soil? • Soilis the portion of Earth’s surface that consists of organic matter mixed with sediment. • Soil is a natural resource that is needed to support life on Earth.

  6. 15.1 What is soil? • There is a big difference between “dirt” and “soil.” • We use the word “dirt” to mean particles and dust that we don’t want around. • Soil contains humus as well as particles of weathered rock including sand, silt, and clay. • Water, air, and living organisms are also important components of soil.

  7. 15.1 How soil forms • Soil is part of the rock cycle. • Factors that affect soil formation include: • climate, • type of parent rock or mineral, • presence of living organisms, • topography, and • time.

  8. 15.1 Layers of soil • A soil profileis a cross-section that shows the different layers (or horizons) of soil in the ground. • Young (or immature) soil does not have as many layers as mature soil. Which soil horizon is the first to form?

  9. 15.1 Types of soil • There are 12 soil types, or orders. • Soil classification is based on the following properties: • How much the soil horizons are developed • Composition of different soil horizons • Amount of organic material • Amount of weathering and leaching of minerals • Presence of calcium carbonate subsurface • Location below grasslands or forests • Presence of clay that shrinks and swells when mixed with water • Presence of permafrost • Presence of volcanic ash

  10. 15.1 General terms for soil types • Focus on three types of soil: pedocal, pedalfer, and laterite. • Pedocal forms in dry or semi-dry climates and is rich in calcium. • Pedalfer forms in humid climates and is high in aluminum and iron. • Laterite forms in tropical climates that have a lot of rains so it is leached of most of its elements.

  11. 15.1 Erosion and agriculture • Soil that contains a mixture of sediments, humus, air, and water is ideal for growing crops. • More soil is lost each year through erosion than is formed by nature.

  12. 15.1 Erosion and agriculture • This soil profile shows the layer of topsoil on a farm in Iowa. • Due to farming, Iowa’s average topsoil depth has decreased from 14–18 inches to only 6–8 inches.

  13. 15.1 Erosion and agriculture • The Natural Resources Conservation Service recommends managing construction projects so that erosion is minimized, intercepting surface runoff so that less soil is lost, planting ground cover, and improving farming techniques.

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