1. Science 7: Unit B Topic 5: Sustaining the Soil

2. Soil Contains a natural community Stores nutrients, air, and water

3. How do Soils Develop? 1.Parent material Mineral matter from which soil developed 2.Climate Warmth/moisture are required for organisms to decompose soil Humus Top soil 3.Vegetation Determines the amount/type of organic matter in/on the soil Protects from erosion 4.Landscape Water levels Water brings new soil and nutrients Spaces between the particles hold water and air for roots 5.Time

4. Soil Horizons The layers in a cross section of soil

5. Soil: A lively Community There are 4 types of decomposers 1.Bacteria Most diverse/numerous

6. Soil: A lively Community 2.Fungi Includes moulds and mushrooms https://www.youtube.com/watch?v=GY_uMH8Xpy0

7. Soil: A lively Community 3. Actinomycetes are a specific group as bacteria. Morphologically they resemble fungi because of their elongated cells that branch into filaments or hyphae.

8. Soil: A lively Community 4.Earthworms

9. All You Can Eat! Healthy plants require large amounts of 1.Nitrogen (N) 2.Phosphorus (P) 3.Sulphur (S) 4.Calcium (Ca) 5.Magnesium (Mg) 6.Potassium (K)

10. Challenges and Solutions Salinization: Salty Soil Salt deposits on the soil surface 2 factors lead to salinization Too little vegetation Excess water Solution Replanting areas and lined water canals

11. Organic Matter and Erosion Loss of organic matter is a very serious problem and can lead to soil erosion. If the soil has lost this organic matter the plants may not grow very well, because of the lack of sufficient nutrients in the soil. Ploughing and cultivating the soil too much and the practice of regular summer fallow (cultivating the land to control weeds- by not planting a crop) exposes the soil surface to sunlight and higher temperatures, encouraging bacteria to decompose organic matter at a rapid rate and exposes it to sun and wind- thus creating topsoil erosion

12. Saving the Soil Soil erosion can be solved by planting a cover of vegetation on the surface to slow the flow of water runoff (giving it more time to absorb more water) This vegetation also helps to anchor the soil particles from the wind Zero tilage is one way to accomplish this and it also helps control the growth of weeds. Special farming equipment is also used (seed drills), shelterbelts (rows of trees), modification of waterways, and crop rotation (forage crops to add more organic matter- manure from livestock)

13. Hydroponic Technology Hydroponics is a technique for growing plants, without soil in a water solution This occurs in greenhouses in Canada

14. Saving Soil in Forests Forestry can also have an impact on soils Removal of trees from particular areas can lead to erosion by wind and water. Cut areas often are littered with debris, which has been left to lower erosion (and add organic matter to the soil) and replanting programs are started after the trees have been harvested. Vegetation near waterways is usually left undisturbed