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Chapter 10: Farming: Conventional and Sustainable Practices

Chapter 10: Farming: Conventional and Sustainable Practices. 10.1 Resources For Agriculture. Soils are complex ecosystems Healthy soil fauna can determine soil fertility Your food comes mostly from the A horizon. Soil Formation. Young Soils Strongest Influence Is Parent Material

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Chapter 10: Farming: Conventional and Sustainable Practices

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  1. Chapter 10: Farming: Conventional and Sustainable Practices

  2. 10.1 Resources For Agriculture • Soils are complex ecosystems • Healthy soil fauna can determine soil fertility • Your food comes mostly from the A horizon

  3. Soil Formation Young Soils • Strongest Influence Is Parent Material Mature Soils • Strongest Influences: Climate, Vegetation, Drainage

  4. Never Safe From Weathering

  5. Soil Formation Processes Leaching from Surface • K, Mg, Na • Ca • Si • Al, Fe Accumulation beneath Surface • Al, Fe in Humid Climates • Ca in Arid Climates • Clay (Mechanical Movement)

  6. Soil Horizons and Profiles • Soil Horizons • Layers in Soil • Not Deposited, but Zones of Chemical Action • Soil Profile • Suite of Layers at a Given Locality • Some CSI myths • You can’t generally identify a soil from surface material • You can’t generally pinpoint a location from a soil sample

  7. Principal Soil Horizons • O: Organic (Humus) • Often Absent • A:Leaching • K, Mg, Na, Clay Removed • B:Accumulation • Absent in Young Soils • Distinct in Old Soils • Al, Fe, Clay (Moist) • Si, Ca (Arid) • C:Parent Material

  8. Limits of Soil Formation • Balance Between: • Downward Lowering of Surface • Downward Migration of Horizons • If erosion rapid or soil evolution slow, soils may never mature beyond a certain point. • Soils on Steep Slopes • Soils in Arid or Cold Climates • Extremely ancient soils may have lost everything movable

  9. Soil Classification • May be the most difficult classification problem in science • Varied Bases for Classification • Age • Parent Material • Climate and Drainage • Multiple Objectives • Scientific • Agricultural • Engineering

  10. "The 7th Approximation" • U.S. Soil Conservation Service • 12 Soil Orders

  11. "The 7th Approximation"

  12. Mollisols Feed The World

  13. Aridisol, Kuwait

  14. Ultisols:AlabamaTennessee

  15. Soils of the U.S.

  16. Oxisol, California (a Paleosol)

  17. Soils and Organisms • Bacteria • Fungi • Nematodes • Springtails • Earthworms (not always good?) • Aerate and Mix Soil, but…. • In northern U.S. and Canada, most are exotic • Consume Organic Matter

  18. 10.2 Ways We Use And Abuse Soils • Arable land is unevenly distributed • Soil losses reduce farm production • Wind and water move most soil • Deserts are spreading around the world

  19. The Counterfeit Paradise • Year-round growing season – but --- • Tropical Soils are nutrient poor • Tropical ecosystems ruthlessly recycle nutrients • Agriculture rapidly depletes nutrients • Slash and burn agriculture • Need for Fertilizer for intensive agriculture • Hardpan development

  20. 10.3 Water And Nutrients • All plants need water to grow • Plants need nutrients, but not too much • "Brawndo's got what plants crave. It's got electrolytes" • Farming is energy-intensive • Global Food Production = 6 x 1015cal/yr = 25 x 1018 J/yr • Global Energy Use = 474 × 1018J/yr

  21. Farming is energy-intensive • Global Food Production = 6 x 1015cal/yr = 25 x 1018 J/yr • Global Energy Use = 474 × 1018J/yr • Direct Agricultural Energy Use = 1% of Total or about 5 x 1018J/yr • By Some Estimates We Use More Energy Than We Get Out • We Cannot Grow Enough Crops to replace Fossil Fuels

  22. 10.4 Pests And Pesticides • People have always used pest controls • Modern pesticides provide benefits, but also create problems • Kill beneficial organisms • Toxic to humans • Resistance • There are many types of pesticides

  23. People have always used pest controls

  24. People have always used pest controls

  25. 10.5 Environmental Effects Of Pest Controls • Pesticides accumulate in remote places • Many pesticides cause human health problems • Hormone Disruptors • “Organic” Pest Control Can Backfire • Mongooses in Hawaii to Control Rats • Cane Toads in Australia to Control Beetles • Mosquito Fish (Worldwide)

  26. 10.6 Organic And Sustainable Agriculture • What does “organic” mean? • Careful management can reduce pests • Useful organisms can help us control pests • Integrated Pest Management uses a combination of techniques

  27. 10.7 Soil Conservation • Contours reduce runoff • Ground cover protects soil • Reduced tillage leaves crop residue • Low-input agriculture can be good for farmers and their land • Consumers’ choices play an important role

  28. Natural and Human Processes • Most human processes are “natural” • What’s unnatural: • Rate of human processes • Scale of human processes • We Now Move More Material Than Natural Erosion

  29. Soil Depletion • Wind • Water • Remedies • Windbreaks • Contour plowing • Strip Cropping • No-till Agriculture

  30. Contour Plowing

  31. Strip Cropping

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