Soil characterisation Flashcards
how does soil science of America define soil?
its the unconsolidated/organic matter on the immediate surface of the earth serving as a natural medium
what is typical make up of soil?
made up of minerals (45%), 5% organic material, and around 25% air and water however this does change in proportion
Soil forming processes?
they are determined by climate and organisms acting on local surface materials
what can affect soil formation?
climate, organisms, relief, parent material and time are all important affecting soil formation, “relief can hasten or delay the influences of climatic factors” Milne 1935
How do you categorise soil?
it is a physical and chemical description of the horizons, make up where pedogenic processes aren’t active the horizons have formed from organic parent material
what is the O Horizon?
litter and humus layer, differentiated by degree of decomposition and its often missing in cultivated soils or lawns
what is the A Horizon?
mix of organic and mineral components, most ideal soil known as top soil
What is the E Horizon?
the eluvial layer, stripped of clay and staining agents, lighter in colour and lower in organic matter
what is the B Horizon?
zone of illuviation that have been leached from overlying horizons
what is the C Horizon?
it is the lightly weathered parent material
properties of soil?
soil colour (determine nature of soil properties and horizons), mottle colour is a secondary colour not associated with composition
soil texture
three particle size classes
sand, silt and clay
soil structure
all to do with shape, size and distinctiveness, finer texture means stronger structure determining soil porosity
Consistency and plasticity
is strength at which soil holds together or resistance to deformation
macro porosity
this is shape and arrangement of soil amount of space between particles, water fills these spaces.
