Week 5 - Why are soils different? Flashcards
What is a soil forming factor? Why are soils different?
- Parent Material
- Climate
- Topography
- Organisms
- Time
- combination of these
Discuss Parent Material
- soils develop on range of parent material
- soils develop directly by weathering of consolidated rocks in situ or transported material
Transportation: Colluvial - gravity Alluvial & Fluvial - water Aeolian - Wind Glacial - Ice
Discuss Climate on Soil Formation
Temperature:
- Affects rate of rock mineral weathering and synthesis of soil (rate of reaction & diffusion of products)
- biological growth and decomposition enhanced
- around 3 fold increase per 10 degrees increase
Moisture:
- under wet or humid climates moisture accelerates weathering and formations
- net downward movement of water
- leeching of soluble minerals
- translocation of clay particles
*Aspect affects the moisture and temperature
List the different Clay materials and their environment
Wet & warm environments (much weathering) - Kaolinite
Extreme weathering environments - silicon from clays mobile and leached leaving iron and aluminium oxides although quartz remain (frameworks)
Semi-arid dry areas (little weathering) - montmorilionite
Discuss Topography on Soil Formation
Relief
- affects local climate, vegetation and drainage of landscape
- angle of slope affects proportion of soil run-off to inflitration
Aspect
- direction of the slope, you tell by the way you are facing the slope
- can change the amount of surface exposed to climate (weathering)
Discuss Organisms on Soil Formation
Plant growth - soil cover reduces erosion
Soil invertebrates - earthworms, termites, ants = increase soil structure & pedoturbation (involves mixing between soil horizons)
Micro-organisms breakdown organic matter
Discuss Time on Soil Formation
Over time we can see that as processes occur within the soil and composition can change. We see formation and decomposition of soils (weathering).
