Soil and Land

Question 1

What does soil thickness reflects?
How do we measure soil thickness?
What’s the difference between erosion and weathering?

Answer 1

It reflects the balance between the rates of soil production and rates of downslope

Input +- output= thickness
rock weathering +- soil transport = thickness

erosion: rock materials carried away by winds, water
weathering: degradation of the rocks without displacement

Question 2

What are the factors of soil formation?

Answer 2

Climate
- temperature& precipitation affects formation
- greater rainfall, faster rate of leaching and erosion
-warmer temp, more decomposition

Organisms
- different plants species
- plants and animals activities produce humic acids as a strong weathering agent
- plants stabilize soil profile, whereas animals/ human activities tend to increase erosion

Topography
- slope/ aspect (eg. north-facing slope, south facing slope)
- steep slope: no soil (accumulated soil will be washed away)
- Flat slope: thick slope
- lowland valley: fertile soil (water&loose materials wash down from upland, accumulates at lowland)

Parent material
- finely textured parental material–> tends to weather into finely textured soil
- coarsely textured parental material–> tends to weather into coarsely textured soil
- Darker minerals–> yield more fetile soil

Time
- reaction needs much time to take place

Question 3

Identify the different layer in the soil profile

Answer 3

• organic matter
• organic and mineral matter
• accumulated clay materials
• weathered matherials from the bed rock

Question 4

1.What are the three different kinds of mineral matters?

2.How are they related to soil texture?

3.What’s the difference between soil texture and soil structure?

4. What can affect soil structure?

Answer 4

1.Clay, silt, sand
2. soil texture is decided by the percentage of clay, silt, sand in the soil
- soil texture triangle

3. soil structure: the arrangement of different components/ soil particles into discrete aggregation
4. -actions of burrowing organisms
   - growth of plants roots
   - wetting & drying
   - freezing& thawing

Question 5

1.What kind of rock is most of the land?
2. What are land pollution?
3. How is land pollution caused?
4. what impacts does it bring ?

Answer 5

1. regolith
2. Land pollution is the deterioration of earth’s land surface at & below ground level
3. caused by the accumulation of solid/ liquid waste materials that have contaminate groundwater & soil
4. affects human, plants, animals
   contributes to air, water pollution

Question 6

1. How do we define land degradation?
2. what are the causes?
3. What are the consequences?

Answer 6

1. deterioration and loss of productive capacity of land because of human activities… exclude natural causes
2. -over grazing , agricultural activities, vegetation removal
   inappropriate irrigation
3. • loss of land resources
   • reducemet in productive capacity of land
     -loss of biodiversity
     -affects ecological system

Question 7

1.How is desert defined?
2. What is Orographic deserts

Answer 7

1. any place with aridity index> 4
   aridity index= possible evaporation /available moisture
2. • deserts that exits at the leeward side of major mountains.
   • under the orographic effect, air is forced to go upward over the mountain, it condenses and rain out. While dry air goes down and warm, promoting evaporation. Thus, a desert climate is formed at the leeward side

Question 8

1.What is woody plant encroachment?
2.What causes it ?
3.How do we manage it?

Answer 8

It is a global phenomenon where shrubs and grasses grows in areas where they were historically less abundant

2. suppression of fire, overgrazing , climate change, high concentration of CO2
3. reforestation
   managed animal grazing
   soil restoration, fixation of soil..