week 5 material Flashcards
(26 cards)
Why are soils so important?
Directly contributes to a number of Sustainable Development Goals
What is Soil security?
the maintenance and improvement of the global soil resource to produce food, fibre and freshwater
What is soil?
The uppermost part of the earth’s surface that has been affected by weathering, new mineral formation, organic matter accumulation, erosion and deposition, and that forms the natural medium for the growth of land-based vegetation
What are soils characterised by?
horizons, or layers or the ability to support
rooted plants in a natural environment.
Why are horizons distinguishable?
result of additions, losses, transfers, and transformations of energy and matter
What is the upper limit of soil?
the boundary between soil and air, shallow water, live plants, or plant materials that have not begun to decompose
What would be the components of optimal loam soil?
Air 25%
Water 25%
Mineral Particles 45%
Organic Matter 5%
What is soil formation a function of?
Soil forming processes
Soil forming factors
What are some examples of Additions?
includes organic material (leaf litter, bark etc), dust, solutes, water
What is Translocation?
– Vertical and lateral movement of inorganic and organic material between different horizons
– Mostly moved by water, but can be moved by biota
– Main process in forming soil horizons
What is Transformation?
soil constituents are chemically or physically modified
What are the different soil forming factors?
parent rock climate time Relief Flora, Fauna and Micro-organismss
What are the different parent materials?
- Bedrock
- Transported material
- Organic material
What are the different forms of transported material?
– Alluvial sediments (deposited by rivers) – Colluvial sediments (deposited by gravity/hillslope) – Aeolian sediments (deposited by wind) – Glacial till or periglacial sediments
What are the different climate effects?
- Rainfall effects
* Temperature affects
effects of temperature on soil?
– Water balance in the soil
– Rates of chemical reactions and decomposition
processes
– Soil biota at all scales
What are organisms effects on soils?
- Vegetation
- Cryptogams
- Bioturbation by fauna
- Micro-organisms
What is relief?
Configuration of the land surface: – Topography – Slope – Aspect – Elevation – Landscape position
What are the Four soil forming processes?
Additions, losses, translocations,
transformations
What are the Five soil forming factors?
parent material, climate, organisms, relief
and time
What are the effects of time on soils?
Thicker horizons that sink deeper into parent material Increased iron accumulation making soils redder or yellower Increased clay content with depth Increased acidity (soil with lower pH) Nutrient leaching so soil is less fertile
What are the different kinds of soil loses?
– Leaching
– Erosion
– Decomposition of organic matter to form CO2
Where does calcification occur?
in low rainfall areas
process of Calcification?
- Slight downward leaching of soluble compounds occurs
- Soil water evaporates
- Calcium carbonate precipitates in subsoil
