1. Grade 8 Chapter 12-1 Conserving Land and Soil

2. Objectives Describe how people use land Discuss the kinds of problems that occur when soil is not properly managed Discuss the nitrogen cycle

3. Types of land Use Agriculture Less than 1/3 of the lands surface is tillable land The rest is too wet, too dry, too salty,or too mountainous New farmland is created by Draining wetlands, Clearing forests Irrigating deserts

4. Agriculture

5. 2 nd Type of Land Use Development First occurred near water or fertile soils, later moved to other areas. The construction of Homes, roads, bridges, and other structures

6. Land Use Development

7. 3 rd Type of Land use Mining – the removal of nonrenewable resources such as iron, copper and coal from the land Strip mining involves removing a strip of land to obtain the minerals and then replacing the strip. May cause erosion as materials are more exposed to the elements Strip mined area may remain barren for years Underground Mining Deep deposits. Talus may cause pollution due to leaching.

8. Mining

9. Restoring the land Land reclamation – the process of restoring the land to a more natural productive state. More expensive than maintaining the land.

10. Protecting the soil Layers of soil Topsoil Litter (humus) Mineral material Contains plant nutrients Takes many years to replace Subsoil Weathered rock material Parent Material ( Bed Rock) Cannot support plant life When soil is not protected it may erode, become a desert or be depleted

11. Erosion Process by which wind, water, gravity or ice moves particles of rock or soil. Rate of erosion is effected by soil management practices and Land use practices Planting cover plants Mining Agriculture activities Land use

12. Erosion

13. Desertification The advance of desert-like conditions into areas that previously were fertile. Caused by Overgrazing Poor Farming practices Excessive cutting of fire wood

14. desertification

15. Nutrient Depletion The removal of nutrients from soils by plants which results in lower soil fertility. Nutrient depletion can be prevented by Leaving fields fallow Leaving crop residue on fields Crop rotation

16. Nitrogen Cycle The process by which nitrogen is removed from the atmosphere, fixed in the soil by bacteria, incorporated into other living things, and then released back into the atmosphere.

17. Nitrogen Cycle

18. Review What are three ways people use land? What are three problems that can occur when soil is not managed properly? Why is it important to protect the topsoil Describe two methods for reducing erosion Describe the Nitrogen cycle