5.3 Flashcards
1
Q
properties of fertile soils
A
- high organic matter –> provides high water retention capacity & good soil structure
- organisms to break down organic matter and return nutrients back
- essential nutrients and minerals
- a suitable pH
2
Q
role of succession in soil fertility
A
- primary s: development of a community from bare rock to climax community
- organisms die & decay –> providing nutrients and the soil becoming more fertile + complex
3
Q
inputs, outputs, and processes that impact soil nutrient levels
A
- inputs:
- outputs:
- processes:
4
Q
cause of soil loss and degradation
A
- water & wind erosion
- chemical degradation
–> Salination = water evap. leaving behind salt & salt accumulating
–> Acidification = an increase in hydrogen concentration lowering the pH - physical degradation: soil compaction
5
Q
positive feedback e.g.
A
marginal land is cleared and used –> increase in erosion and land degradation –> increase in poverty –> marginal land being cleared and used
6
Q
factors contributing to desertification
A
- overgrazing
- deforestation/land clearance
- farming methods
- drought/climate change
7
Q
The Dust Bowl - case study
A
- 1930s USA –> caused by drought, poor farming, and windy conditions
- land was plowed after harvest and left empty = wind erosion due to lack of vegetation cover
- drought dried out the soil –> wind swept it up
8
Q
different types of water erosion
A
- sheet erosion = equal amounts of soil taken away (looks like oil)
- rill erosion = looks like tree branches
- gully erosion = creates a deep channel
9
Q
techniques to reduce water erosion
A
- vegetation cover –> intercepts rainfall & reduce erosion
- reducing run-off using terracing
- furrow diking = creating furrows with small ridges to capture the water
- contour tillage = plowing down a slope along natural contours of land
- strip cropping so they absorb the water
10
Q
conventional vs conservational tillage
A
- tillage is used to prepare the soil for sowing seeds
- conventional: soil is physically broken up plowing –> loose soil that is aerated (also helps reduce weed) + any crop residues are plowed into soil nothing left on surface
- conservation: crop residue is left as a mulch on the surface –> increases water infiltration, reduces run-off and water erosion
11
Q
techniques to reduce wind erosion
A
- windbreaks: trees or large scrub to reduce wind velocity & capture flying soil
- shelter belts: blocks of trees or shrubs planted at right angles to the wind to deflect and reduce velocity
12
Q
Sahel - case study
A
- holes in the soil to capture water –> reduce run-off and imrpove soil moisture
