Chapter 12 Notes
12.2
What is parent material?
MATERIAL FROM WHICH SOIL IS FORMED
What is residual soil? A soil whose PARENT material is the bedrock beneath the soil.
The Bluegrass region of Kentucky is an example of a residual soil.
What is transported soil? Soils formed elsewhere and deposited, by winds, rivers, and
glaciers, in other locations. An example would be soils in the Midwest and New
England are transported.
What is Humus? Fertile, rich, soil formed from ORGANIC materials such as
decaying plants and animals. Nitrogen is abundant in humus. Found in the
uppermost layer of the A horizon.
12.3 Mass Movement and Erosion
Define Erosion: The removal and transport of materials by natural agents such as
wind and running water.
Types of mass movement
Landslide: movement of a mass of bedrock or loose soil and rock down the slope of a
hill, mountain, or cliff.
Creep: VERY slow movement of soil down a slope. While you might not see the
movement, you will know it happened because fence posts, trees or other things
planted in the soil will begin to lean downhill.
Slump: Blocks of land tilt and move downhill along a surface that curves into a
slope. This happens when a slope is too steep and the bottom of the slope cannot
support the top of the slope.
Earth flows: a mass of water soaked weathered material flows downhill.
Mudflows: Rapid movement of water tat contains large amounts of clay and silt
(mud).
12.4 Soil as a resource
Soil fertility: the ability of a soil to grow plants.
Soil depletion: when the soil is over farmed and gradually becomes lacking or
depleted in the necessary nutrients for growing crops.
What are ways that soil depletion can be reversed?
Add fertilizers, rotate crops, don’t use a field for a time so that it can naturally
replenish its nutrients, or add fertilizer. Fertilizers are not the best way to improve
soil due to the ecological hazards that fertilizers can create.
Ways to reduce soil erosion:
1. Windbreaks – plant trees along the edges of fields. This stops/breaks the wind
and reduces the impact of the wind on the field’s erosion.
2. Contour Farming: Prevents water from flowing rapidly downhill and carrying soil
with it. Instead of planting in rows up and down, the farmer plants in rows that
follow the contour of the land.
3. Terraces: Flatten slopes into terraces to prevent run off.
4. Strip Cropping: Alternating a row of crops that leaves bare ground with a row that
covers the ground. An example would be corn in one row (bare ground beneath
the stalks) with alfalfa, which covers the ground.