Soil Forming Factors Flashcards
What are soil forming factors?
The things that affect the way soil is being made or formed all the time☺️
How many years does it take to form 10mm of soil?
200 years
Name the five main soil forming factors.
- topographical/ Geographical factors ( R)
- Climatic factors ( CL)
- Biological factors ( O)
-Parent material ( P) - Time( T)
What are geographical factors? Why are they important?
They are the shape of land and affect where the soil is formed
Name features of geographical factors?
Aspect or direction
Altitude or height
Angle of slope
What is altitude? How does it contribute to soil formation?
It is the height of land above sea level.
Temperatures on the upper surface are very extreme and fluctuate continuously. They are cold at night and very hot in the day. The continuous contraction and expansion of rocks on mountains causes the rocks to weaken and over time weather
What is the angle of slope? How does it affect soil formation?
It is how steep or gradual/ gentle the slope is. The is more soil formation on gentle slope that steep slopes because gentle slopes hold on to water and when mixed with water they cause hydrolysis
What is aspect or direction? How does it affect soil formation?
It is the direction that the slope faces.
Slopes facing the north are warmer and evaporation rate is higher rather than South facing slopes that are wetter and cooler. The is more weathering on South facing slopes because of hydrolysis and carbonation. The amount of rain also affects the decomposition process
Which slopes weather more? Facing towards the sea or away from the sea.
Why?
Towards the sea.
Because the amount of rainfall they receive is higher than those facing away from the sea resulting in hydrolysis and carbonation
What are climatic factors?
Factors that affect the long term weather patterns of an area.
Name the climatic factors.
Temperature
Rainfall
Wind
Sunlight
Humidity
How does temperature and rainfall affect soil formation?
Fluctuating temperatures causes rocks to expand and contract continuously weakening them and then they eventually crack and begin to weather
Rainfall affects soil formation by hydrolysis and carbonation which weakens the rocks and make them weather leading to soil formation
How does wind and sunlight contribute to soil formation?
Wind speeds up soil formation and weathering by blowing particles from one place to another.
Sunlight affects soil formation by hotter temperatures and moisture leading to faster decomposition and weathering
How does humidity contribute to soil formation?
It increases the rate of decomposition of organic matter
What are biological or organisms factor?
They are factors caused by living organisms that contribute to soil formation.
List the biological factors that contribute to soil formation.
Vegetation
Animals
Mesofuana
Human activities
How does vegetation contribute to soil formation?
Plant roots penetrate through rocks causing them to widen and eventually crack.they result in weathering and soil formation.
When plants die they add organic matter and minerals to the soil, (humus) which is the first layer Of horizon in the soil
What is the function of plant roots?
They hold the soil together. Reducing erosion and making the soil stable
What is mesofuana?
Medium sized organisms that live in the soil.
Give examples of mesofuana
Nematodes and mites and beetleworms
How do micro organisms contribute to soil erosion?
They break down organic matter and nutrients leading to decomposition.
Give examples of micro organisms that live in the soil
Fungi
Bacteria
Termites
How do mesofuana contribute to soil formation
The beetleworms and earthworms mix organic matter and rock particles leading to soil formation.
They bring air to the soil when they burrow and move around
What agricultural activities contribute to soil formation
Planting vegetation
Leaving bare soil covered with mulch
What is parent material
The underlying geological or bedrock that from which soil horizons form
Give examples of how parent material can be formed
When particles are blown from one place to another
When rocks weather or humus is formed
What determines the properties of the soil during early stages of parent material.
Character and chemical composition
What are the soluble-ions in parent material?
Magnesium, Potassium, sodium and calcium
What are the properties of the soluble ions in parent material
Available to plants
Easily dissolved in water
What has a direct impact on soil chemistry and fertility
Parent material composition
In what weather/ climate conditions does soil formation occur the most?
Warm and wet conditions
How many years does it take to form 2cm of soil
1000 years
Does time affect how quickly soil forms?
No, it is the type of soil and environment that determines it. Soil in another area can form faster than soil in another area in the same span of time
How long does it take to form 1m of soil in tropical African countries
75000 years
How many years does it take to form 10mm of soil in South Africa
300 years
What is the difference between soil formation in other countries and south Africa which 10mm
100 years
300-200=100 years
Why does it take longer for soil to form in South Africa
Because it’s exposed to humid and hot climate so it takes a lot of time for lichens to hold on to the soil and begin weathering process
Why is time important in Soil formation
It determines the seasons and how long each period has
Which horizon takes less time to develop
Surface horizon
What is steady soil state?
When the horizon and properties do not change for long periods of time
Name 3 things that occur in the soil over time
Thicker horizons sink deep into parent material
The is an increased iron accumulation in the soil which makes the soil redder
The is increased acidity
