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5.1 Introduction to soil system - Coggle Diagram
5.1 Introduction to soil system
Soil forming process
Factors affecting soil charactheristics :
climate
organisms
Relief
Parent material
Time
soil forming process involve :
Transfer
Translocation
Leaching
-Decomposition
Weathering
Nutrient cycling
transfer
gains and losses of material to and from the profile
biological mixing
burrowing animals like earth worms, ants, etc.
leaching
downward loss of nutrients through soil layers.
Transformation
Weathering
Nutrient cycling
Decomposition
Soil structure and properties
sand, loam, clay
sand
moderate mineral content
highest drainage
low water holding capacity
highest air space
sufficient space to live
high potential to hold organic matters
low productivity
clay
limited mineral content
poor drainage
highest water holding capacity
little space for colonization
low potential to hold organic matters
waterlogged crops above
loam
high mineral content
intermediate drainage
intermediate water holding capacity
have most space for biota to live
good mix of organic matter
highest productivity in balanced soil
benefits of soil to support plant growth
anchorage for roots
supply of water
supply of oxygen
supply of mineral nutrients
protection against adverse changes of temperature and pH
physical condition that restrict root geowth
mechanical barriers
absence of cracks
shortage of oxygen due to waterlogging
dryness
temperature that are too high or too low
chemical conditions that restrict root growth
high aluminium concentration
low nutrient supply
trace metals or salinity associated with insecticide or herbicide
Soil as a system
open system
linked to other environmental system (climate and vegetation)
plays a central role in many biogeochemical system
provide a short term storage for chemical elements
main interface between biotic and abiotic process within ecosystems
INPUTS:
organic materials (leaf litter), parent materials, precipitation, infiltration, energy, inorganic matter (from parent material), atmospheric input (C, N, etc)
OUTPUTS:
Energy, uptakes by plants, mass movement, radiation, soil erosion, nutrient loss and gaseous loss:
Nitrogen, water, heat, soil particles/erosion, CO2, methane
TRANSFERS (within the soil)
biological mixing, translocation and leaching (minerals dissolve in water
moving through soil).
TRANSFORMATION
decomposition, humification, weathering & nutrient cycling
STORAGES
organic matter, nutrients, organisms, minerals, air and water
example:
soil food web
nitrogen cycle
Soil Profile
O (organic or humus)
A (topsoil)
E (eluviated horizon)
B (subsoil)
C (parent material)
R (bedrock)
O (organic or humus)
Organic horizon, humus layer (vital element for soil
fertility). Its helps to prevent erosion, hold moisture
A (topsoil)
Dark coloured, stained by down washed humus. Layer where seeds germinate, and plants roots grow where Most biological activity occurs here.
E (eluviated horizon
Made up by sand & silt, lighter colour due to removal
of clay and calcium by water (translocation)
C (parent mats)
Possible iron accumulation, brighter colour due to deposition of iron and aluminium, little humus, plant root penetrate through this layer
R (bedrock)
Mineral layer, show little or no sign
of soil formation.
