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AGRICULTURE, THE SOIL, water erosion, overgrazing, removal of natural…

- - - - subsistence: cultivation of food to the farmers and their families. They grow all what they need
      - comercial: cultivate products to sell them.
  - - - arable: production of plants for the humans
      - pastoral: production of animals or animal related products (milk)
      - mixed: both are grown to sell.
  - - - extensive: small amount of production from a large area
        
        less efficient but less environmental conflicts.
      - intensive: large amount of production from a small area
        
        large amount of resources, more efficient, more expensive, environmental conflicts
- - - - cut down forests to use the land to cultivate food
        
        produce more food
        
        reduce the animals and plants habitats
      - use more artificial fertilisers and pesticides
        
        produce more food
        
        damage the ecosystem
      - more irrigation
        
        crops grow better
        
        less drinking water
    - - reduce population growth
        
        decreases the demand for food
        
        grow more staple food and fewer luxury items
        
        lot of food is produced
        
        more food equaliy
        
        everyone has similar access to food
        
        eat less meat
        
        less land is needed
- - - - works on the topsoil and it loss affects the fertibilty of the soil
  - - - big clumps of soil are broken into smaller ones
        
        more vulnerable to erosion
  - - - impacts on the whole ecosystem
  - - - contour ploughing
    - - windbreakes
        
        maintaining vegetative cover
        
        adding organic matter
        
        intercropping, crop rotation and mixed cropping
- - - - weathering and erosion of the parent rock
        
        physical weathering
        
        The proportion vary depending on
        
        how was it managed
        
        local climatic conditions
        
        type of soil
        
        size of mineral particles
        
        chemical weathering
        
        biological weathering
      - sand (largest)
        
        large pores
        
        drains well
        
        allows water and air
        
        large and irregular shape
        
        poor retention of nutrients
        
        easy to cultivate
        
        difficult for plants to anchor and get water
      - clay (smallest)
        
        minusculus pores
        
        holds water, not allow air
        
        the densest and heaviest
        
        poor for farming
        
        don't drain well
      - silt
        
        medium in shape
        
        smaller pores
        
        holds water and nutrients better than sand
        
        allows air
        
        the most fertile
  - - - descomposers (worms, bacteria) break down the dead matter and plants use them as nutrients
  - - - fill spaces in the soil
        
        dry conditions - air increase - water decrease
        
        rainy conditions - air decrease - water increase
- - - - depends on the parent rock and the water that flows into it
  - - - Best for agriculture
      - Is the perfect mixture of humus, clay, silt and sand
      - retain nutrients
  - - - stores and prevents the loss of mineral nutrients
      - increases water-holding capacity in sandy soils
      - increases air spaces in clay soils
      - increases the number of decomposer organisms