1. Soil Resources Chapter 15

2. What is Soil? Composed of: mineral matter organic matter Modified by: weather water organisms

3. What is Soil? How Soils are Formed From parent material Formation time varies (200 – 1000 years) Depth varies (thin film to 10 ft)

4. What is Soil? Soil Composition

5. What is Soil? Soil Composition Other components: Humus

6. What is Soil? Soil Composition Other components: Pore space (wet soil) Pore space (dry soil)

7. What is Soil? Soil Horizons

8. What is Soil? Soil Organisms

9. What is Soil? Nutrient Cycling

10. What is Soil? Nutrient Cycling (alternate slide) Organic matter in soil Decomposition Minerals freed and available to plant Plant roots absorb minerals from soil Elements incorporated into organic matter in plants Elements in organic matter in animals

11. Soil Properties and Major Soil Types Soil Texture: Sand, Silt, and Clay

12. Soil Properties and Major Soil Types Availability of nutrient minerals in clay

13. Soil Properties and Major Soil Types Soil Properties Affected by Soil Texture

14. Soil Properties and Major Soil Types Soil Acidity pH scale 0 7 14 Most soils (pH = 4-8) Pygmy Forest Death Valley

15. Soil Properties and Major Soil Types Major Soil Groups

16. Soil Properties and Major Soil Types Major Soil Groups

17. Soil Properties and Major Soil Types Major Soil Groups

18. Soil Problems Soil Erosion Caused by water, wind, and ice

19. Soil Problems Case-in-Point: The American Dust Bowl

20. Soil Problems Nutrient Mineral Depletion

21. Soil Problems Soil Problems in the United States Cultivated soils in southern Iowa, northern Missouri, western and southern Texas, & eastern Tennessee have greatest erosion 25% of agricultural lands lose more topsoil than formed

22. Soil Problems World Soil Problems Mineral depletion in tropical rainforest soils Degradation in the African Sahel

23. Soil Conservation and Regeneration Conservation Tillage

24. Soil Conservation and Regeneration Crop Rotation CORN 1 st Year SOYBEANS 2 nd Year OATS 3 rd Year ALFALFA 4 th Year

25. Soil Conservation and Regeneration Contour Plowing, Strip Cropping, and Terracing Strip cropping & contour plowing Terracing

26. Soil Conservation and Regeneration Preserving Soil Fertility Organic fertilizers e.g., manure, compost slow release, but nutrient content varies Commercial inorganic fertilizers e.g., typical bagged fertilizer exact nutrient content known, but prone to leaching

27. Soil Conservation and Regeneration Soil Reclamation increasing productivity on eroded land Shelterbelts