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Food and Agriculture

Food and Agriculture. How to feed the ever expanding population Currently 5.8 billion 30 years 12 billion. Modern methods in Agriculture. Green Revolution Blue Revolution. What’s needed to grow food?. soil - the outer weathered layer of the earth's crust.  Water Light nutrients.

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Food and Agriculture

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  1. Food and Agriculture How to feed the ever expanding population Currently 5.8 billion 30 years 12 billion

  2. Modern methods in Agriculture • Green Revolution • Blue Revolution

  3. What’s needed to grow food? • soil - the outer weathered layer of the earth's crust.  • Water • Light • nutrients

  4. Soil contains both Biotic and Abiotic Components • Topsoil is the upper 1 ft of land that is usable for plant growth • Composition is clay:sand:silt defines the character of the soil • Topsoil varies in different Biomes • Grasslands are the riches • Tropical Rainforest are some the poorest

  5. organic matter - typically about 1% in nature litter - partially decayed organic matter on the soil surface.  humus - highly decomposed, fine, amorphous organic matter in the soil. 

  6. Bacteria and Fungi Decompose Organic Matter • Micorrhizal Symbiotes (tree and fungi) enhance mineral uptake into plants • Worms, Nematode and Insects decompose organic matter and aerate the soil

  7. Soil Horizon

  8. Land Degradation • Overgrazing • Deforestation • Agricultural activities • Overexploitation • Industrialization

  9. water and wind are the main agents of erosion Trees and Ground Cover Prevent erosion.

  10. Why has 100 years of farming in the U.S. resulted in a loss of ½ of all cropland? • Row crops • Deep plowing • Heavy herbicide use (no ground cover) • Machine made gullies • Chemical fertilizer • No rotation of crops • monoculture

  11. 72% of all fresh water (rivers, lakes and ground water) is used for irrigation • Over-watering leads to • Loss of Oxygen • Salinization

  12. Fertilizers Provide Inorganic Nutrients • Major: N, K, P, C, Mg,S • Applied Fertilizer • 1950: 20 kg/ha • 1990: 91kg/ha Phosphates and nitrates from farm field and cattle feed lots are aquatic pollutant.

  13. Alternative Ways to Fertilize • Manure • Crop residues • Ashes • Composted refuse • Green manure • *nitrogen fixing crops

  14. Climate: The greenhouse effect • Increasing CO2 increases productivity

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