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Environmental Sciences: Towards a Sustainable Future Chapter 8

Why a Study of Soil Is Important. 90% of the world's food comes from land-based agriculture.Maintenance of soil is the cornerstone of sustainable civilizations.Simply stated, it is the

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Environmental Sciences: Towards a Sustainable Future Chapter 8

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    1. Environmental Sciences: Towards a Sustainable Future Chapter 8 Soil and the Soil Ecosystem

    2. Why a Study of Soil Is Important 90% of the world�s food comes from land-based agriculture. Maintenance of soil is the cornerstone of sustainable civilizations. Simply stated, it is the �foundation� of terrestrial life.

    3. Golden Rules of Sustainable Agriculture Cover the soil Minimal or zero tillage Mulch for nutrients Maximize biomass production Maximize biodiversity

    4. Global Trend: Where Did All the Farms Go? Poor farming practices = loss of soils and farmland. Erosion Salinization Development in United States = loss of 1.4 million acres of farmland per year.

    5. Soil Profile (Soil Science Education Web page)

    6. Topsoil Formation

    7. Soil Texture Soil texture refers to the percentage of each type of particle found in the soil. Loam soil is approximately 40% sand, 40% silt, and 20% clay.

    8. Soil Texture Sand Silt Clay

    9. Soil Texture

    10. Soil Texture and Properties

    11. Soil Classes Mollisols: fertile soils with deep A horizon; best agriculture soils Oxisols: iron and aluminum oxides in B horizon; little O horizon; Poor agriculture soils

    12. Soil Classes Alfisols: well-developed O, A, E, and B horizons; suitable for agriculture if supplemented Aridisols: little vertical structure; thin and unsuitable for sustainable agriculture

    13. Plant-soil-water Relationships

    14. Productive Soil Good supply of nutrients and nutrient-holding capacity Infiltration, good water-holding capacity, resists evaporative water loss Porous structure for aeration Near-neutral pH Low salt content

    15. Soil: IT�S ALIVE!

    16. Humus Partly decomposed organic matter High capacity for holding water and nutrients Typically found in O horizon

    17. Humus: To Be or Not to Be

    18. Desert Pavement

    19. Causes of Soil Degradation

    20. Soil Degradation

    21. Prevention of Soil Erosion Change in attitude on national and local level Federal programs encouraging sustainable land use Focus of university agriculture programs

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