bedrock:
rock thats structurally apart of/connected to earths crust
regolith:
any loose fragmented earth material that covers bedrock
what is soil?
- the upper most material of terrestrial environments.
- provides chem and phys needs of plant life (including water)
- contains minerals (from rocks) and organic matter
- soil isnt just dirt (the solid factor)
- it contains gas and liquid components too
- soil atmosphere contains O2 and other gases from air, and CO2 and methane from the soil.
- soil water contains dissolved substances such as nutrient’s for the plants
how does soil form? (soil formation aka pedogenesis)
5 factors !
1) parent material
2) climate
3) organisms
4) relief
5) time
1) parent material (underlying rock)
The nature of the parent mat. will influence the composition of the soil made from it
2) relief (topography)
slope of the environment and its aspects whether it faces N, S, E, W
3) climate
- measure of temperature and precipitation
- precipitation influences downward movement of mat.
- temp influences decomposition
4) organisms
Biological activity of plants, animals, and microbes (bacteria and fungi) is essential for good soil development
5) time
properties of soil develop over time in centuries
S.P - colour
- colour of soil changes with depth in its profile
- colour can come from the parent material or processes of the location
- munsell soil colour chart
S.P - texture
- based on the particles of sand, silt, and/or clay present in the sample
- clay > silt > sand. clay retains the most water
- determines different factors (e.g ability to retain water and how much gases in it)
S.P - structure
- refers to the way particles are grouped together into soil masses called PEDS
- shape and size of peds influences movement of water + air
S.P - minerals
parent material
↓
primary minerals
↓
secondary minerals (changes from primary)
- Clay minerals are the most important secondary bcus they hold plant nutrients
through chemical interactions.
S.P - chemistry
- pH of soil, how acidic/basic it is
- primary nutrients: nitrogen, phosphorus, potassium
- pH affects nutrients availability for plants (e.g farmers alter the soil pH to suite their needs)
S.P - moisture
- water comes from precipitation.
- some water flows over surface, some infiltrates the soil
- water leaves soil through evaporation, transpiration, and leaching (aka percolation)
soil horizon:
distinct layers that are different in phys or chem composition, organic content, or structure
- we follow the canadian system of soil classification CSSC for naming horizons
soil horizon
- Horizons develop from the removal or accumulation of chemical compounds, usually by water movement
- Horizons are separated into organic and mineral groups
soil profile: soil pedon: polypedon:
the full set of horizions in a location down to its parent material.
a small division of soil column in an area showcasing these properties
area of the same type of soil type, made of many pedons
Organic Horizons
- top most layer of the soil profile
- O horizon
- formed from material that accumulates from plants and animals (organic material)
-humus.
Mineral Horizons
- A, B, C horizons
- the roots of plants penetrate and influence A + B horizons.
A Horizon
Mineral soil at surface where mixed with organic humus
- mineral and humus
B Horizon
where drained/filtered materials accumulate
- high concentrations of clay located here
C Horizon
- weathered rock
- little to no organic material
- partially altered parent material
- above bedrock
Ah + Ae Horizons (Mineral horizons)
- Ah, darked coloured organic rich layer where biological activity occurs
- Ae, light coloured portion where downward eluviation (transport) has removed clay, o.g matter, iron, and aluminum compounds.
- common subdivision of the uppermost mineral layer
