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Resources 3.4 3.5 3.6
 

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    Resources 3.4 3.5 3.6 Resources 3.4 3.5 3.6 Presentation Transcript

    • DP Environmental systems and societiesTopic 3 Human population carrying capacity and resource use
    • 3.4 THE SOIL SYSTEM
    • Soil systemHow does the soil system interact with all the other systems? •Review nitrogen cycle •Review phosphate cycle
    • 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, 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
    • Deforestation
    • Interaction of soil and watersystems
    • Salinization
    • Erosion
    • 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
    • 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
    • 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
    • Soil management Commercial farm • High technological input • Low labour • High yields • Bad for the environment • GMOs, monoculture, selective breeding
    • 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
    • 3.5 FOOD RESOURCES
    • Food production (2009, $US)
    • Food distribution
    • Terrestrial vs Aquatic systems
    • 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
    • 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
    • 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
    • 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 intensive agriculture Unsustainable use of water - water table dropping 1 meter a year Agricultural output in decline