2. SOILS FORMATION, EROSION, AND CONSERVATION Miller Chapter 10

3. I. Soil: Formation Erosion, and Conservation A.What is Soil? complex mixture of eroded rock, minerals, decaying organic matter, water, air, and living organisms. Ratios Differ among various soil types… Average Ratios: 45% Minerals 25% Water 25% Air 5% Humus

4. B. How Soil is Produced -Weathering of rock -Depositing of sediment -Decomposition of matter

5. C. Soil Zones (MATURE) -Soil is arranged into zones called… SOIL HORIZONS -A cross-section of soil horizons is called… SOIL PROFILE -Most mature soils have at least three of the possible horizons

6. LAYERS/HORIZONS O Horizon – Top layer/Surface Liter Layer -Characterized by debris and animal waste -Brown/black in color

7. A Horizon – Top Soil Layer -Consists of porous mixture of partially decomposed organic matter called… HUMUS Inorganic minerals -Most plant roots and organic matter found here.

8. B Horizon – Subsoil Layer and C Horizon – Parent Material Contain most of soil’s inorganic matter and varying mixtures of sand, silt,clay, and gravel C Horizon lies on BEDROCK

9. Soils: zones O horizon Leaf litter A horizon Topsoil B horizon Subsoil C horizon Parentmaterial Mature soil Young soil RegolithRegolith Immature soil Bedrock

10. D. Soil Properties *Soils vary in content of … Clay Silt Sand Gravel SOIL TEXTURE -Relative amounts of different size and types determines SOIL TEXTURE -LOAMS – -LOAMS – soils of equal mixture

11. 100%clayIncreasing percentage silt Increasing percentage clay 0 20 40 60 80 80 60 40 20 0 100%sand 80604020 100%silt Increasing percentage sand CLAY SILT SAND

13. 1. Infiltration:  Water moving through the soil layers 1. Infiltration:  Water moving through the soil layers

14. 2. Leaching:  Soil components from upper layers being carried to lower layers

15. 3. Porosity:  the measure of the volume of pores and distance of pores per volume of soil

16. 4. Permeability:  the rate at which water and air can move through soil Water High permeabilityLow permeability

17. 5. Soil Structure: The way in which soil particles are organized and clumped together 5. Soil Structure: The way in which soil particles are organized and clumped together TextureNutrientInfiltrationWater-Holding Aeration TilthCapacity ClayGoodPoorGoodPoor Poor SiltMediumMediumMediumMedium Medium SandPoorGoodPoorGood Good Loam MediumMediumMediumMedium Medium

18. 6. Soil pH  A measure of the acidity of the soil

19. II. Soil Erosion 1. The movement of soil components, especially surface litter and topsoil, from one place to another *Two main agents are… -Flowing water -Wind

20. 2. Types Of Water Erosion A. Sheet – Moving of water in wide flow B. Rill – Fast moving water that cuts small channels

21. C.Gully – Ditches and gulley’s are caused by fast moving water over steep, exposed soil

22. Areas of serious concern Areas of some concern Stable or nonvegetative areas Global Soil Erosion

23. 3. U.S. Soil Erosion -1/3 of the original top soil has been washed or blown away. -USDA states that soil is eroding 16x faster than it can form. -USDA estimated loss of $30 billion dollars from erosion in 1997

25. The Dust Bowl

27. A.Desertification- The productive potential of arid or semiarid land falls by 10% or more due to…  Human activities  Climate changes MUST REDUCE…  Overgrazing & deforestation A.Desertification- The productive potential of arid or semiarid land falls by 10% or more due to…  Human activities  Climate changes MUST REDUCE…  Overgrazing & deforestation 4. Other Problems Associated With Soil

28. ModerateSevereVery Severe

29. B. Salinization- The accumulation of salts in soil Often associated with irrigation Effects: Stunts crop growth Lowers crop yields Kills plants

30. Severe Salinization

31. C. Water logging-  An over abundance of water within the soil C. Water logging-  An over abundance of water within the soil Evaporation Transpiration Evaporation Waterlogging Less permeable clay layer

32. III. Soil Conservation 1. Reducing soil erosion and restoring soil fertility.

33. 2. Farming Techniques A. Conventional-tillage farming A. Conventional-tillage farming *Tilling in the fall B. Conservation-tillage farming 1. Minimum Tillage Farming 2. No Till Farming

34. 3. Terracing 3. Terracing – Creation of broad, nearly level terraces that run across the contour of the lands -Mostly used on very steep gradients.

35. 4. Contour Farming- Plowing/planting crops in rows across the sloped contour of the land.

36. 5. Strip Cropping- Alternating rows of crops with low, ground hugging vegetation.

37. 6. Alley Cropping/Agroforestry- several crops planted together in strips or alleys between trees or shrubs

38. 7. Windbreaks/Shelterbelts- Rows of trees to reduce wind erosion.

39. Conservation During Urban Development

40. IV. Soil Restoration - Fertility can be returned by using one of two major types of fertilizer… A. Organic B. Inorganic

41. -Animal manure -Green manure Organic fertilizer -Compost

42. Commercial inorganic fertilizer

44. Extreme Erosion