Soil Formation & Erosion (College Board AP® Environmental Science): Flashcards
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Define soil formation.
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Cards in this collection (25)
Define soil formation.
Soil formation is the process by which rocks break down and organic material accumulates to create soil over time.
How does parent material affect the soil that forms from it?
Parent material determines the mineral composition and texture of the soil.
True or False?
Cold, dry climates speed up soil formation.
False.
Warm, wet climates promote faster soil formation, because temperature and precipitation control the rate of weathering and organic decomposition.
Define soil horizons.
Soil horizons are distinct layers of soil that develop over time due to biological, chemical, and physical processes.
Why do steep slopes tend to have thin soils?
Steep slopes tend to have thin soils because of erosion, while valleys accumulate deeper soils.
Soil formation is a slow process, taking to thousands of years to develop significant layers.
Soil formation is a slow process, taking hundreds to thousands of years to develop significant layers.
How do earthworms and microbes improve soil fertility?
Earthworms and microbes improve soil fertility by mixing and aerating the soil.
Define soil profile.
A soil profile is the vertical arrangement of soil horizons, which helps categorize soil types.
What determines soil texture?
Soil texture is determined by the proportion of sand, silt, and clay in the soil.
Define porosity.
Porosity is the amount of space between soil particles, which affects water and air movement.
The O horizon is also known as the layer.
The O horizon is also known as the litter layer.
Define permeability.
Permeability is how easily water passes through soil.
What does a dark soil color usually indicate?
A dark soil color usually indicates a higher organic matter content; red or yellow soils indicate iron oxides.
Which soil horizon is known as the zone of leaching?
The A horizon (topsoil) is the zone of leaching, as water carries soluble minerals and clay particles downward out of it.
True or False?
The B horizon is rich in organic material.
False.
The B horizon (subsoil) contains little organic material; it is the zone of accumulation, where minerals, clay, and soluble compounds leached from the A horizon collect.
What is the C horizon composed of?
The C horizon is composed of weathered rock fragments (parent material) from which the soil above develops.
Define soil erosion.
Soil erosion is the process by which soil is removed from one location and transported to another by natural forces such as wind and water.
Why do tropical soils have thin topsoil layers?
Tropical soils have thin topsoil layers because of rapid decomposition.
What are the effects of erosion on soil?
Erosion reduces soil fertility, depletes organic matter, and can lead to desertification.
Which human activities accelerate soil erosion?
Human activities that accelerate soil erosion include deforestation, overgrazing, and unsustainable agriculture.
cuts step-like platforms into steep slopes to slow runoff.
Terracing cuts step-like platforms into steep slopes to slow runoff.
What caused the Dust Bowl of the 1930s?
The Dust Bowl was an example of wind erosion that resulted from poor land management and severe drought in the Great Plains.
What is contour plowing?
Contour plowing is plowing along the contours of slopes rather than up and down them.
What is the purpose of growing cover crops?
Cover crops, such as clover or rye, are grown between cash-crop harvests to anchor the soil against erosion.
How does protecting soil also protect water quality?
Healthy soils act as natural filters, removing pollutants and sediments from water before it reaches groundwater or surface water.
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