envr 1000 - unit 6, soil resources and agriculture, pt 2

erosion

the dislodging and removal of material

sediment

eroded material deposited after transport by wind, water or glacial ice

soil erosion as a natural process

• Wind action, desiccation, water erosion

how have humans intensfied unnatural erosion

1. Over-cultivating: poor planning or excessive ploughing
   2. Overgrazing: adding more livestock than the land can support
   3. Deforestation (especially on slopes)

rangeland

grassland that is not intensively managed and is used for grazing livestock

__ hectares of cropland suffer from erosion

19 billion

main culprits of soil degradation?

deforestation, intensive agriculture, overgrazing, pollution

soil degradation over the next 40 years in africa could reduce crop yields by

one half

why is rangeland important? (list a couple reasons)

• Provides fodder for livestock such as cattle,
  sheep, and goats
  - Grasses are predominant rangeland vegetation
  - Fibrous root system, hold soil in place very
  well
  - Grazing animals eat leafy shoots, but leave
  roots in place, allowing re-growth of leaves
  and preventing soil erosion
  - Carefully managed grazing is beneficial for
  grasslands
  - Grazing stimulates growth and animal hooves
  disturb soil to allow better water absorption

overgrazing

When too many grazing animals consume the plants in a
particular area, it can leave the vegetation destroyed and unable to recover
- Undesirable species may then replace the natural grass cover, or erosion may remove
topsoil, leading to permanent degradation

land degradation

Natural or human induced process that decreases the
future ability of the land to support crops or livestock

desertification

Progressive degradation that induces unproductive desert-
like conditions on formerly productive rangeland

what causes desertification?

• climate change

• overgrazing and deforestation

ex of desertification

Mali

• overgrazing

• drought

• human overpopulation

soil contamination

the presence of hazardous chemicals, heavy metals, or synthetic substances in soil at levels that threaten ecosystems and human health

methods to protect soil?

• crop rotation

• intercropping

• agroforestry

• contour farming and terracing

• shelterbelts

• no-till farming

crop rotation

altering crops grown in an area

intercropping

alternating bands or spatial mixing, offering more complete
ground cover (also more ecosystem benefits)

agroforestry

Interplanting crops with trees, which can draw nutrients up from
deeper soils and provide organic material in litter fall

contour farming and terracing

optimizing slope of land by ploughing along contour lines to limit erosion; creating “staircase” plots to retain water and soil

shelterbelts

rows of trees/tall shrubs acting as windbreaks to limit wind erosion

no-till farming

No disturbance to soil through tillage (digging, stirring, overturning) which is used to produce finer soils