Chapter 12. 2 Soil
Chapter 12.4 Soil as a Resource
• 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.
Soil Profile and Horizons
O Horizon: top organic layer of soil, made
mostly of leaf matter & humus
A Horizon: topsoil; gray to black organic-rich,
clay-poor soil with plant material; plant roots
grow here
B Horizon: subsoil; red or brown color from
iron oxides; made of clay & minerals washed
down from above; some roots grow here [clay]
C Horizon: slightly weathered parent material
& rock fragments [pebbles]
D Horizon: un-weathered rock [bedrock
Layer beneath soil is bedrock
Soil Types
• Arctic Soil – Areas with cold climates, rock
materials weather slowly, shallow soil profile
• Temperate Grassland- Areas with
mild/temperate climates, enough rain to grow
grass well but not a lot of trees. Good soil for
farming.
Soil Types, cont.
• Temperate forest soil- Areas with
temperate/mild climates with heavy tree
growth. Good for farming.
• Tropical grassland- Areas with dry/tropical
climate, warm and dry all year with wet and
dry seasons. Rock materials weather quickly,
soil profiles are deep
Soil Types, Cont.
• Tropical Forest Soils- areas with humid
(moist/wet) tropical climate, warm and rainy
all year. Rock materials weather quickly and
soil profiles are deep.
• Desert Soils- areas with little or no rainfall.
Limited vegetation which means more wind
erosion. Sandy soil
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
• 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.
Contour Farming
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.
Terraces
• Terraces: Flatten slopes into terraces to
prevent run off.
Strip Cropping
• 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.