Soils Flashcards
(26 cards)
Where are podzols found?
Under coniferous woodlands and heather moors
High latitudes e.g. Northern Scotland and Canada
More precipitation than evapotranspiration
Podzol O Horizon
Layer of needles or heather leaf litter
Podzol A Horizon
Acidic
Nutrients are leached by water
Podzol E Horizon
Pale, formed of quartz, sand or silt
Acidic water travelling through dissolves aluminium and iron compounds
Podzol B Horizon
Minerals accumulate
Red/Brown in colour
Why are podzols bad for agriculture?
Vulnerable to water logging
Acidity and lack of nutrients mean only a few crops can grow
How can podzols be used for agriculture?
Can be used for arable if treated with lime and artificial fertilization
Mainly used for livestock and logging
Where are tropical red latosols found?
Under tropical rainforests
How deep are tropical red latosols?
30-40m due to high temperatures and humidity encouraging the weathering of bedrock
Tropical Red Latosol O Horizon
Thick due to year round plant growth
Nutrients from humus are absorbed by vegetation rather than staying in the soil
Tropical Red Latosol A Horizon
Fertile but very thin
Tropical Red Latosol B Horizon
Leaching of silicate compounds as rainfall is higher than evapotransipration causing a moisture surplus
Iron and aluminium compounds left behind
Why are tropical red latosols poor for agriculture
Low nutrient content
Vulnerable to heavy rainfall, leading to high rates of leaching
How have tropical red latosols been adapted for agriculture?
Slash and burn can add nutrients to the soil
What uses do tropical red latosols have?
Cattle ranching in the Amazon
Useful for building as it is hard when it dries out
What are the causes of soil erosion?
Clearing of vegetation - rain falls directly on to the soil, soil is exposed to wind, roots holding the soil together are removed
Ploughing - makes the soil vulnerable to wind
Topography - soil is more likely to be washed away on a steep slope
High rainfall - increases water erosion
Low rainfall - soil dries out and is more vulnerable to wind
What are the impacts of soil erosion?
Loss of nutrients
Soil is less able to hold water
How can soil erosion be managed?
Crop rotation - cover crops can maintain the soil until the main crop is sown again
Wind breaks - hedges or trees can be used to protect against wind erosion
Terracing and contour ploughing - slows the movement of water down a slope
Mulching - protects the soil from wind and slows down run off
What are the causes of water logging?
Soils with few air spaces fill up with water quickly e.g. clay
Precipitation higher than evapotranspiration
Too much irrigation
What are the impacts of water logging?
Root growth may be prevented or they may even rot
Water can decrease the soil temperature, reducing growth
Crops may be out competed by weeds
Land is hard to plough
How can water logging be managed?
Reduced irrigation
Contour ploughing/terracing
Drainage
What are the causes of structural deterioration?
Removal of the vegetation that retains structure
Livestock or machinery compacting soil
Salinisation causing soils to clump together
What are the impacts of structural deterioration?
If compacted, plants can’t grow
Loss of pore spaces can cause plants to dry out due to a lack of water
Land is hard to plough
How is structural deterioration managed?
Moving livestock regularly
Adding sand to clay soils
Avoiding salinisation
