Soils (yr1) Flashcards
Contour ploughing
Ploughing along contours of land in order to minimise soil erosion
Desertification
Fertile land becomes desert typically as a result of a drought, deforestation or inappropriate agriculture
Edaphic
Of, produced by or influenced by the soil
Mulching
Treat or cover with mulch
Multi cropping
Growing two or more crops in the same piece of land in the same growing seasons instead of one crop
Ploughing
Turn up the earth with a plough especially before sowing
Sedimentation
The process of settling or being deposited as a sediment
Soil compaction
Stress applied to soil causes densification as air is replaced or displaced by the soil
Soil structure
Arrangement or way soil is arranged
Soil texture
Determines soil classes based on physical texture
Soil fertility
Ability of soil to sustain plant growth
Strip cropping
Cultivation in which different crops are sown in alternate strips to prevent soil erosion
Surface runoff
Flow of water occurring on the ground when excess water can no longer sufficiently rapidly infiltrate in soil
Terracing
A sloped plain cut into a series of successively receding steps
How does Thermal Capacity affect different soil types?
Clay soils retain water easily. Water has a higher thermal capacity so theses soils warm up and down slowly compared to sandy soils
How does Drainage affect different soil types?
Sandy soils - large pores so good water drainage
Clay particles - smallest pores so slower drainage
How does Aeration affect different soil types?
Sandy soils have larger particles with greater pore spaces so they have higher air content
How does Nutrient Levels affect different soil types?
Sandy soils - rapid drainage causes leaching of nutrients
Clay soils - clay particles have a negative surface charge so positively charged mineral ions stick to their surface
How does Root Penetration affect different soil types?
Sand particles are looser because of the lack of adhesion by surface water so they allow better penetration.
How does Capillary Action affect different soil types?
Tiny pore spaces between clay particles allow water underground to rise towards the surface.
There is no capillary action/rising in sandy soils
How does ploughing/drainage affect soil fertility?
Could increase fertility as allows aeration (which speeds up decomposition) of soil and can reverse compaction, aiding drainage
How does compaction affect soil fertility?
Decrease
Less infiltration, reduced root penetration
How does Irrigation affect soil fertility?
Increases
Adds water
How does pH control affect soil fertility?
Increases
Adds lime/chalk/buffer solution to make optimum pH to stop nutrient leaching
How does pH control affect soil fertility?
Increases
Adds lime/chalk/buffer solution to make optimum pH to stop nutrient leaching
What is the optimum pH of soil?
5.5 - 7
How does fertillisers affect soil fertility?
Increase
Inorganic - adds nitrates/phosphates
Organic - adds carbon
What is splash erosion?
Raindrops falling and hitting bare soil and disturbing the soil structure. Particles are dislodged and move into the pore spaces, reducing infiltration.
What is surface runoff?
Water erosion that dislodges particles and moves them elsewhere.
If there is a loss of root binding (e.g. after deforestation) then there is a likelihood of landslides following heavy rainfall
What is wind erosion?
The removal of fertile soil from the land and a formation of dune systems. More common in dry areas of low rainfall. Particles are moved across the surface by the wind; small ones are picked up and moved long distances. Agricultural soils are most at risk when exposed without plant cover.
What are 5 natural features that reduce soil erosion?
- Raindrops impact is reduced by vegetation cover (interception)
- Natural vegetation acts as a windbreak
- Vegetation and other soil biota increase infiltration rates, so reduced surface runoff
- Soil organic matter binds the soil particles together
- Roots binding the soil together
Universal soil loss equation (usle) is given in exams but need to be able to understand it
Erosion rate = RxKxLxSxCxP Where: R = Rainfall erosivity factor K = Soil erodibility factor L = Slope length factor S = Slope gradient factor C = Cropping management factor P = Erosion preventing factor
7 human activities causing soil erosion?
- Clearing vegetation e.g. removing hedgerows
- Cultivating on steep slopes
- Loss of soil biota
- Ploughing vulnerable soils
- Overgrazing of cattle
- Compaction from heavy machinery e.g. tractors
- Deforestation = less interception
How is a landslide caused?
When soil becomes wet, increased mass and lubricated with a lack of vegetation and root binding causes land movement.
More at risk after heavy rainfall.
How is sedimentation caused?
Soil particles are carried into rivers due to surface run off. Increased turbidity and particles downstream can lead to reduced river volume. The river is at risk of flooding
How is desertification caused by soil erosion?
Loss of soil fertility leads to less vegetation growth.
less vegetation = more erosion and less rainfall
How is desertification caused by soil erosion?
Loss of soil fertility leads to less vegetation growth.
less vegetation = more erosion and less rainfall
