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Soils

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Soils

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  1. Soils Soils are the result of weathering Mechanical Chemical Critical resources for food, timber, textiles... Waste filters Understanding soils is important for land-use planning, and engineering

  2. Idealized soil profile from a humid climate at middle latitudes Zone of Leaching

  3. Horizon Development and Climate

  4. Soil textural classes

  5. Topsoil ecosystem in a temperate climate

  6. Porosity and Permeability Water saturation and air space Nutrients to plant roots

  7. The Water Table The level below which the soil is saturated with water (no air space)

  8. Soil water Representative water budgets Deficiencies can be remedied by storage andirrigation

  9. Effect of climate on soil development

  10. The Principal Soil Types

  11. hot hot laterites Temperature pedocals pedalfers tundra soils cool cold low 50 cm/yr high Precipitation Effect of climate on soil types tundra soils

  12. Principal soil types in the USA

  13. Effect of climate on soil types A typical pedocal with white caliche (CaCO3) deposits in a shallow B horizon

  14. Tundra soil Laterite Effect of climate on soils Making laterite bricks Temple at Angkor Wat Cambodia (700 yrs old)

  15. Pf Pc Pf Pf, Pc L Pf, L A Newer Classification of Soil Types

  16. Rates of soil formation: Central USA: ~ 1 cm/100 years in very porous and permeable rock Humid N. Carolina: ~ 1 cm/5 years “ Granite may require over 1000 years for a cm

  17. Universal Soil Loss Equation A = RKLSCP • A = long-term average annual soil loss for site • R = long-term rainfall runoff erosion factor • K = soil erodibility index • L = hill slope/length factor • S = hill slope gradient (slope) factor • C = soil cover factor P = erosion-control practice factor

  18. Both Ends of the Erosion Problem Serious soil erosion and gully formation related to diversion of water runoff over a few months in central California Sediment pollution following heavy rains in North Carolina

  19. Soil Degradation • Erosion • Deforestation • Agricultural depletion • Contamination - Pollution • Salinization • Pesticides • Chemical additions and spills • Urbanization • Desertification • Overgrazing

  20. Soil Erosion Raindrop impact: millions in a single shower hit at ~ 30 mph

  21. Soil Erosion Rill-wash and gullying in loose and poorly-consolidated soils

  22. Soil Erosion

  23. Soil Erosion Number of dust storms during the month of March, 1936

  24. Effects of logging in Madagasgar

  25. Soil Erosion Figure 3.12: (a) a natural forested slope (b) the same slope following a clearcut

  26. Soil Erosion Figure 3.12: (c) the same slope after conversion to farmland (b) the same slope following urbanization

  27. Soil Erosion

  28. Soil Erosion 1968 motorcycles first come to Deer Creek near Bakersfield, CA 1972 after only 4 years of ORV use little vegetation or topsoil remains

  29. Soil Erosion ORV users increased from 21 to 38 million between 1982 and 1992 ATVs rip through a marsh in West Virginia Great Grizzly Hike, Montana

  30. Soil Erosion 1985 photo of bulldozer and jeep tracks in Alaskan tundra made in 1946

  31. Soil Erosion

  32. Salt accumulation due to irrigation in an arid climate: San Fernando Valley

  33. Worldwide Distribution of Salt-affected Soils

  34. Chemical Contamination of Soils

  35. Grain production levels off while population continues to grow

  36. Cleaning Up Chemical Contamination

  37. Combating Soil Degradation

  38. Combating Soil Degradation

  39. Combating Soil Degradation Strip-cropping and Contour plowing

  40. Combating Soil Degradation Rice terraces in Asia

  41. Combating Soil Degradation No-till Farming

  42. Soil Surveys and Adequate Planning