7.3 Flashcards
Describe the steps in the formation of soil.
1) The soil forming process begins when weathering breaks bedrock into smaller pieces.
2) many organisms (bacteria, fungi, insects) begin to live I weathered materials. Over time these organisms die, decay, and add nutrients to the weathered material to form soil.
3) nutrients begin to be added to the soil, soil texture improves, and the soil’s capacity to hold water increases.
What is soil the result of?
Chemical and mechanical weathering and biological activity over long periods of time.
What does soil form in?
Layers. Solid bedrock from which weathered pieces of rock first break off is known as the parent rock. As pieces of weathered bedrock break off they form on top of the parent rock.
What is the difference between residual soil and transported soil?
Residual soil is the soil located above its parent material and transported soil has been moved to a location away from its parent bedrock by agents such as running water, wind, and glaciers.
What are the three major soil horizons? Describe each.
-A, B, C
A: high concentrations of organic matter and humus. Soil rich in humus are usually dark coloured; they range from gray to black.
B and C: less developed soil. B contains subsoils that are enriched with clay minerals. Accumulation of clay in the Bhorizon can cause the formation of hard materials commonly called hard pan. Horizon C contains weathered parent materials.
How does topography affect the thickness of developing soil?
Because in sloped areas, where runoff occurs, the courser particles of soil remain on the slopes while the smaller particles move downslope. As a result, soils on slopes tend to be thin and soils formed in lower areas are thick. Also, south facing soils receive more sunlight and more vegetation so they are thicker.
What are t effectors that contribute to the development of soil?
Vegetation which, overtime, can grow and mature in soil and increase the rate of soil development. Vegetation contributes to the buildup of humus and supplies acids to promote the weathering process. Parent bedrock, topography, plants and animals, time, temperature.
What are the 4 different types of soil in the world? (Just list).
1) polar
2) temperate
3) desert
4) tropical
Describe polar soil.
- where does it form?
- what is it good for?
- what doesn’t it have?
- what is present under it?
- where is it found?
- forms at high latitudes and high elevations.
- good drainage but no distinct horizons because they are shallow
- permafrost is often present under thin polar soils
- Greenland, Canada, and Antarctica
Describe temperate soil.
- what is it able to support (describe soil)?
- what determines the vegetation?
- vary greatly; able to support diverse environments (prairies, forests, grasslands)
- annual rainfall and specific amount will determine the vegetation
- grasslands- rich, fertile soil
- forests- less fertile
- prairie- dryer with grasses and bushes
Describe desert soils?
- what does it have high levels of?
- what can it support?
- does it have little or lots of organic matter?
- abundant___?
- describe the appearance.
- high levels of accumulated salts and can only support limited vegetation
- little or no organic matter- very thin A horizon
- abundant nutrients; during rain able to support many plants
- light coloured, course, may contain salts and gypsum
Describe tropical soil.
- why is it often infertile?
- what cause few nutrients and humus?
- what does it leach?
- what is its red colour due to?
- where is it found?
- intensely weathered and often infertile soil due to high temp and heavy rainfall
- intense weathering and hight bacterial activity cause few nutrients and humus
- leaching of soluable materials
- red colour- iron ore
- Brazil, Australia, Jamaica
List the three particles of soil, from smallest to largest.
Clay, silt, and sand
What makes soil fertile?
The availability of minerals and nutrients, number of microorganisms present, the amount of precipitation available, topography, and the level of acidity. Farmers will use natural and commercially produced fertilizers to replace minerals and maintain soil fertility.
How do soil horizons differ from one another?
Based on how developed the soil is. Poorly developed soils show little distinction between layers wheras develped soils show great distinction.
