DP Environmental systems            and societiesTopic 3 Human population carrying capacity and                           ...
3.4 THE SOIL SYSTEM
Soil systemHow does the soil system interact with all the other systems?                               •Review            ...
Soil horizons
Soil profile               •Soil profile               •Soil horizons               •Soil formation
The best soil type: loam
Soil degradation    Erosion        • Water erosion makes 60% of soil degradation    Overuse        • Overgrazing, overcrop...
Deforestation
Interaction of soil and watersystems
Salinization
Erosion
Soil conservation        Reduce water flow        • Contour ploughing        • Terracing        • Gullies and ravines fenc...
What issues can you see here? Bad: • Slope  increased erosion • Fields very large • Monoculture – crop rotation? Good: • ...
Soil management Subsistence farm •   Only enough food for family or small community •   Labor intensive •   Linked with po...
Soil management Commercial farm •   High technological input •   Low labour •   High yields •   Bad for the environment • ...
Another way to describe farming:Extensive farming – Farms that are large in comparison to the money and labour put into th...
3.5 FOOD RESOURCES
Food production                  (2009, $US)
Food distribution
Terrestrial vs Aquatic systems
Food productionsystems  North American                            Subsistence  cereal farming                         farm...
Food productionsystems    Intensive beef                                            Maasai tribal use of     production in...
Food productionsystems    Commercial                                                  Rice-fish farming in salmon farming ...
Water resources3.6 WATER RESOURCES
Earth’s water budget
Water system
Case studyPunjub region the bread belt forIndia   Relies on groundwater for irrigation      Increasing population and     ...
Resources 3.4 3.5 3.6
Resources 3.4 3.5 3.6
Resources 3.4 3.5 3.6
Resources 3.4 3.5 3.6
Resources 3.4 3.5 3.6
Resources 3.4 3.5 3.6
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Resources 3.4 3.5 3.6

  1. 1. DP Environmental systems and societiesTopic 3 Human population carrying capacity and resource use
  2. 2. 3.4 THE SOIL SYSTEM
  3. 3. Soil systemHow does the soil system interact with all the other systems? •Review nitrogen cycle •Review phosphate cycle
  4. 4. Soil horizons
  5. 5. Soil profile •Soil profile •Soil horizons •Soil formation
  6. 6. The best soil type: loam
  7. 7. Soil degradation Erosion • Water erosion makes 60% of soil degradation Overuse • Overgrazing, overcropping, increasing erosion • Slash and burn techniques leave nutrient poor soils Deforestation unproductive after several crop cycles, increasing erosion Acidification • Also called toxification, releases toxic metals • Minerals in the water concentrate in the soil in dry or coastal Salinization areas Desertification • Spreading of desert into once productive areas • Increasing all the above problems due to change in land use Climate change and hydrology
  8. 8. Deforestation
  9. 9. Interaction of soil and watersystems
  10. 10. Salinization
  11. 11. Erosion
  12. 12. Soil conservation Reduce water flow • Contour ploughing • Terracing • Gullies and ravines fenced and planted with trees Erosion control after harvest • Keep crop cover as long as possible • Keep stubble and root structure after harvest • Plant a grass crop or crop rotation Long term • Smaller fields • Grow a tree crop • Wind barriers • Stop use of marginal lands • Use of lime or organic material to improve soil condition
  13. 13. What issues can you see here? Bad: • Slope  increased erosion • Fields very large • Monoculture – crop rotation? Good: • Tree buffers that can absorb surface runoff, lower wind erosion • Harvest does not allow soil to be exposed • Contour ploughing
  14. 14. Soil management Subsistence farm • Only enough food for family or small community • Labor intensive • Linked with poverty • Good for the environment • no GMOs, polyculture, limited selective breeding
  15. 15. Soil management Commercial farm • High technological input • Low labour • High yields • Bad for the environment • GMOs, monoculture, selective breeding
  16. 16. Another way to describe farming:Extensive farming – Farms that are large in comparison to the money and labour put into them eg. large cattle ranchesIntensive farming – Farms that are small but have high output (due to capital and labour) eg. feed lots for cattle
  17. 17. 3.5 FOOD RESOURCES
  18. 18. Food production (2009, $US)
  19. 19. Food distribution
  20. 20. Terrestrial vs Aquatic systems
  21. 21. Food productionsystems North American Subsistence cereal farming farming in SE Asia Inputs: Inputs: High technology, high fertilizer Low technology, natural fertilizers, high use, low labor labor System characteristics: Genetically modified organisms, System characteristics: monoculture Polyculture, crop rotation Environmental: Clearance of natural ecosystems, loss of species diversity, soil erosion Environmental: Sustainable Outputs: Low hectare efficiency output as is Outputs: extensive not intensive, but high Only enough to feed family or small farmer output community, high efficiency
  22. 22. Food productionsystems Intensive beef Maasai tribal use of production in livestock MEDCs Inputs: Inputs: High technology, heating, food Low – no fences, only human input System characteristics: System characteristics: Nomadic form of subsistence farming Selective breeding, intensive farming Socio-cultural: Cattle the source of all social roles and Socio-cultural: status Ethics of restrained animals Environmental: Environmental: Low impact, but social gains of wealth and Greenhouse gases, waste, transportation quantity can lead to overgrazing and desertification Outputs: Outputs: High relative to extensive beef farming Low – subsistence farming, efficiency high
  23. 23. Food productionsystems Commercial Rice-fish farming in salmon farming in Thailand Norway/Scotland Inputs: Inputs: High use of antibiotics and steroids Low technology, high labor, fish stock System characteristics: Polyspecies System characteristics: Monoculture, high selective breeding Environmental: More natural ecosystem but relies on Environmental: introduced species Food taken from ecosystem depleting other species, good in that it leaves wild stocks of Socio-cultural: salmon alone to breed Competition from poultry, beef, pork, and marine fish Outputs: Outputs: High efficiency and high output per High output per hectare, low output per hectare and per farmer farmer
  24. 24. Water resources3.6 WATER RESOURCES
  25. 25. Earth’s water budget
  26. 26. Water system
  27. 27. Case studyPunjub region the bread belt forIndia Relies on groundwater for irrigation Increasing population and intensive agriculture Unsustainable use of water - water table dropping 1 meter a year Agricultural output in decline

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