5.1 Soil (DP IB Environmental Systems & Societies (ESS): SL): Flashcards
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Define infiltration.
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Cards in this collection (28)
Define infiltration.
Infiltration is the process by which water enters the soil from the surface.
Define percolation.
Percolation is the downward movement of water through the soil layers.
Define leaching.
Leaching is the loss of dissolved minerals and nutrients as they move down through the soil profile.
What are the four main components of soil?
Soil is made up of inorganic (mineral) matter, organic matter, water and air.
Define humification.
Humification is the transformation of organic matter into stable humus.
True or False?
Infiltration is an example of a soil transformation.
False.
Infiltration is a transfer, since it involves a change in location rather than a change in chemical nature, state or energy.
Define decomposition.
Decomposition is the breakdown of organic matter by microorganisms, releasing carbon dioxide, water and nutrients.
Weathering, decomposition, nutrient cycling, salinisation and humification are all examples of soil .
Weathering, decomposition, nutrient cycling, salinisation and humification are all examples of soil transformations.
What are anthropogenic inputs to the soil system?
Anthropogenic inputs to the soil system are human-made additions such as compost, fertilisers and irrigation water.
Define soil profile.
A soil profile is the layered structure of distinct horizons that develops in soil through long-term interactions within the soil system.
Which four factors influence the development of a soil profile?
Soil profile development is influenced by climate, vegetation, parent material and time.
How does soil composition typically change with depth in a soil profile?
Soil profiles typically change from organic-rich layers near the surface to more mineral-rich layers deeper down.
Why do peat soils in boreal forests such as Scandinavia contain thick layers of partially decomposed organic matter?
In Scandinavian peat soils, cold, wet conditions slow decomposition rates, allowing partially decomposed organic matter (peat) to accumulate.
True or False?
Desert soils typically have thick, organic-rich topsoil.
False.
Desert soils are typically shallow and mineral-dominated, due to low organic matter input and minimal leaching.
Define soil texture.
Soil texture is the physical make-up of soil, determined by the relative proportions of sand, silt, clay and humus.
Define humus.
Humus is dark, crumbly organic matter formed from the partial decay of dead plant material in soil.
How can sand, silt and clay be distinguished using the feel test?
In the feel test, sand feels gritty, silt feels smooth and clay feels sticky when wet.
What are the three main methods used to determine soil texture?
Soil texture can be determined using a soil key, the feel test or a laboratory settling test.
Why do sandy soils, such as those in East Anglia, UK, require more frequent irrigation?
Sandy soils drain quickly and do not retain enough moisture for some plants.
In urban areas, compacted clay soils often need added to improve their structure and aeration.
In urban areas, compacted clay soils often need organic matter added to improve their structure and aeration.
True or False?
Well-aerated soils limit plant root growth and microbial activity.
False.
Well-aerated soils support root growth and beneficial microbial activity.
What three key functions do soils carry out within terrestrial ecosystems?
Soils support plant growth, biodiversity and biogeochemical cycles.
True or False?
Plants obtain carbon from the soil in the same way as nutrients such as nitrogen and phosphorus.
False.
Carbon is an exception; plants obtain carbon from the atmosphere, not the soil.
Soils act as a natural , providing a substrate for seed germination and root development.
Soils act as a natural seed bank, providing a substrate for seed germination and root development.
Why do tropical forest soils typically act as a carbon source rather than a long-term carbon store?
Warm, moist conditions accelerate decomposition, so carbon is released back into the atmosphere quickly.
Why can tundra, wetland and temperate grassland soils accumulate large amounts of carbon?
Cold temperatures and waterlogged conditions slow decomposition, allowing organic matter to build up rather than being released as CO2.
Why do the fertile soils of the Amazon rainforest support such diverse plant life?
The Amazon rainforest's soils contain high levels of essential nutrients, supporting its diverse plant life.
How do the soils of UK ancient woodlands contribute to biodiversity?
Ancient woodland soils are rich in biodiversity and support rare fungal species that play important roles in nutrient cycling.
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