Soil Flashcards
Why is soil important? (1)
- a store of water and nutrients for plants and crops
What is soil made of? (5)
- organic remains from dead plants and animals
- mineral particles - mainly from underlying rocks
- soil organisms
- air in the spaces between soil particles
- water in the spaces between soil particles
What is subsistence farming?
Farming for a household or community (mixture of crops/ eco-friendly)
What is commercial farming?
Producing food for large-scale for maximum profit (monoculture/ one type of crop)
What is extensive farming?
uses more land with lower volume of plants ( low output)
What is intensive farming?
Uses more land with a greater density of plants (high output)
Explain Subsistence farming in LEDCs
-small scale
-labour intensive
-use of draft animals (donkeys)
-no burning of fossil fuels
-limited regulation
Explain Commercial farming in MEDCs
- lots of heavy machinery -> damages the soil
- uses of fossil fuels
- increased legislation on commercial farming to reduce the level of pollution
- use of buffers to reduce risk of eutrophication
What will define the texture of soil?
Different % of clay, sand and silt will determine the texture of soil
Finish the statement:
Particles greater than 2mm = ?
pebbles.
if the particle is greater than 2mm it is a pebble
What are the properties of clay soil?
- holds lots of water
- hard to plough
- slow to absorb and release water
- no air pockets for biotic species
What are the properties of sand soil?
- porous
- not much organic material
- lots of air pockets for animals
What is the ideal soil type?
loam
What are the properties of loam soil?
- porous
- lots of air pockets
- retains moisture
- enough organic material for drainage to avoid waterlogging
What are the levels of soil?
- O-Horizon
- A-Horizon
- B-Horizon
- C-Horizon
- R-Horizon -> Bedrock (Parent material)
Explain the properties of the O-Horizon of soil
- newly added organic material
Explain the properties of the A-Horizon of soil
where the dead organic material and fine particles (the humus) build up. It releases soluble minerals absorbed by plants
Explain the properties of the B-Horizon of soil
soluble materials and organic material, tends to be clay, is deposited from the layer above
Explain the properties of the C-Horizon of soil
Weathered rock
what is soil degradation
the change in the soil health status resulting in a diminished capacity of the ecosystem to provide goods and services for its beneficiaries. They do not provide the normal goods and services of the particular soil in its ecosystem
what is the pattern of soil degradation
- Along the equator (hot and dry)
- Sahara desert has soil degradation without vegetation
- Australia deserts - lack of rich soil
- UAE deserts
- Northern China - snow -> lack of soil
why is soil so valuable?
- fertile soil produces crops for increasing populations
- to store and purify water
- for timber
- stores carbon
- 2000 years to generate 10cm of topsoil
- poor soil can lead to famine, forced migration and conflict
- used for fuel resources
what 2 processes cause soil degradation
- soil erosion - wind and water take the soil away when the vegetation is gone
- chemicals end up in the soil and soil becomes less useful in the long run
what are the 5 human causes of soil degradation and erosion
- deforestation -> without plant cover, erosion can sweep the land into rivers. The plants that replace the tress (cotton, soybean), cant usually hold onto the soil, worsening the soil erosion
- overgrazing -> reduce ground cover, enabling erosion and the compaction of land by wind and rain. This reduces the ability for plants to grow and water to penetrate, which harms soil microbes
- agriculture -> when agricultural fields replace natural vegetation, the topsoil is exposed and can dry out. Diversity decreases + nutrients wash out
- use of agrochemicals -> overuse pesticides and other chemicals disrupts the balance of the microorganisms in the soil
- overcropping -> depleted soil nutrients and makes soil more susceptible to soil erosion (1930s suffered the ‘Dust Bowl’ through overuse of land twice the size of the UK leading to server wind erosion that moved soil thousands of kilometers)
what are 4 effects of soil degradation
- desertification
- loss of arable and fertile land
- clogged and polluted waterways (soil and pesticides into waterways, damaging marine ecosystems)
- increased flooding (converted land is less able to soak up water, making flooding more common)
what are the solutions to soil degradation
-> using less pesticides/ using natural fertilisers
-> crop rotation
-> Regulations to prevent deforestation
-> regulations against certain agro chemicals
-> addition of soil conditioners
-> wind reduction (planting trees and bushes)
-> improved irrigation
-> stop plowing marginal lands
what 3 major processes causes soil erosion
- sheet wash -> large areas of soil are washed away during heavy storms and in mountainous areas (landslides)
- Gullying -> channels develop on hillsides following rainfall. Over time these become much deeper
- wind erosion