soils Flashcards
what are zonal soils?
a soil which has experienced the max effect of the climate and natural vegetation
what are the 5 essential soil functions?
physical stability and soils hydrologic buffer food biodiversity and habitat nutrient cycling filtering and buffering
what is nutrient cycling?
carbon, nitrogen, phosphorus and many nutrients are stored, transformed and cycled in the soil
what is food, biodiversity and habitat?
the diversity and productivity of living things depends on soil
what is the hydrologic buffer?
soil helps control where rain, snowmelt and irrigation water goes.
what is filtering and buffering?
the minerals and microbes in the soil are responsible for filtering, buffering and detoxifying organic and inorganic materials
what is physical stability and support?
soil structure provides a medium for plant roots
what are different layers of the soil?
O -humus A- topsoil B- subsoil C- rock being weathered D- bedrock
what are the 2 types of soil profile?
tropical red latosol
podsol
what is the humus layer?
it is a thin layer of rooting vegetation - such as grass and leaves
what is the topsoil?
this layer is rich in humus and minerals from the rock
so it is good for growing crops
what is the subsoil?
it has little humus but is rich in minerals
what is rock that is being weathered?
it has been broken into chunks already
what is the bedrock?
solid rock, mot yet weathered but it will be one day
what is rill erosion?
when rainfall does not soak into the surface it can gather on the surface and runs down hill forming channels called rills
what is sheet erosion?
as raindrops loosen soil the overland flow can transport topsoil
what is saltation?
main process of soil transportation
what is creep?
occurs when particles greater than 0.5mm are too heavy to be lifted by wind
what is wind erosion?
occurs when forces exerted by wind overcome the gravitational and cohesive forces of soil particles
what is gully erosion?
if rills are unattended to they grow into larger gullies
what is river bank erosion?
soil is washed away by unmanaged rivers as they meander across floodplains
repeated erosion reduces the fertility of the soil by…
- removal of topsoil
- reduction in depth of soil
- reducing infiltration
this in turn can lead to…
loss of seeds, fertilisers and pesticides
young plants being sand blasted
increased difficulty of field operations
damage to the environment includes…
- deposition of sediment onto roads land and into dams
- manage to quality of water courses
- increased run-off and sedimentation causing greater risk to flooding
what are the causes of soil erosion?
deforestation
what are the solutions to soil erosion?
plant fast growing trees
place terraces and small dams to hold soils
the key to reducing soil erosion by rainwater is to reduce the amount of surface flow water by…
installing field drains
reducing the amount of water running onto fields
use of manure to stabalise topsoil
protecting the soil in winter
what is salinisation?
a build up of salts in the soil
what are the problems with salinisation?
excessive water application - rainwater contains salts
how much farmland is affected by salinisation?
estimated 10-20%
what are the 4 soil structures?
granular and crumb structures
blocky structures
prismatic and columnar structures
platy structures
granular and crumb structures?
individual particles of sand, silt and clay grouped together in small nearly spherical grains
blocky structures
soil particles that cling together in nearly square or angular blocks
prismatic and columnar structures
soil particles which have formed into vertical columns or pillars separated by verticle cracks
platy structures
made up of soil particles aggregated in thin plates or sheets piled horizontally on one another
