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SoilJordan Del Guercio
Ryan Lee
Matt Jun
Nick Tang
APES Per. 5
Importance of Soil• provides physical support and nutrients
for plants, allowing them to live
• greatly affects both above-ground and below-ground ecology
• above-ground usually affects plants
• below-ground affects organic matter and decomposers
Earth’s Spheres• lithosphere – inorganic, rocky
crust
• hydrosphere – water
• biosphere –all living organisms
• atmosphere – air that surrounds planet
• each sphere contains a different amount of soil
Amount of Soil• lithosphere – soil is present, but it lacks nutrients and minerals
• hydrosphere – none
• biosphere – soil is present to support living organisms such as plants
• atmosphere – none
Soil Formation• soil forms
spontaneously from rock, which fragments as a result of heat, cold, wind, rain, hail and ice
• it is formed under high temperature and pressure
Factors of Soil Formation
• climate
• topography
• organisms
• time
• parent material
Climate• the quality of soil at the end of the soil formation process depends on the climate
• temperate regions: able to absorb nutrients, swells under moisture
• hot/humid regions: arable but easily dried, not able to hold nutrients
• cold regions: soil is similar to sand
Soil in a Temperate Climate
• contains minerals and nutrients that help plants grow
Soil in a Humid Climate
• easily dried, not able to hold minerals or nutrients
Topography• steepness of the soil’s location can affect runoff of water and vegetation
• parent material needs to lie undisturbed
Parent Materials• Geological material where soil horizons
form, made of weathered minerals
• Physical weathering: materials are broken down, usually occurs due to temperature
• Chemical weathering: parent material releases minerals and nutrients
Soil Structure• O-Horizon – where the nutrients come
from
• A-Horizon – nutrients absorbed by lower horizons, rich in organic matter
• B-Horizon – where nutrients are accumulated
• C-Horizon – withered soil
• R-Horizon – unexposed parent material
Loam• mixture of sand, silt and clay
• 40% sand, 40% silt, 20% clay
Loss of Soil• produced naturally at a rate of 1mm in 200-400 years
• soil is currently being lost as much as 40 times as much of its natural replacement rate
Desertification•Desertification is the persistent degradation of dryland ecosystems by climatic variations and human activities
Desertification•Desertification occurs as a result of a long-term failure to balance human demand for ecosystem services and the amount the ecosystem can supply
Causes of Desertification
•Poor management of agriculture•Globalization•Population growth
•Desertification effects a wide range of services provided by ecosystems to humans
Effects
Such as: food and water, climate regulation, and soil conservation
Sediments
• Soil erosion occurs when particles are transported down-hill towards ever faster flowing rivers
• In slowly moving waters, silt and sand are deposited with some mud, creating very fertile soil.
• In the sea, thick layers of sediment are formed as water is squeezed out and the sediment compacted to form sedimentary rocks.
The End of the Soil Cycle
• When subjected to extreme pressure, by being pushed deep down, or by colliding forces, sediment rock will metamorphose into new, harder rock forms like gneiss, schist, greywacke and marble. These weather like the original igneous rocks, to form sand, silt and clay.
Works Cited