Download Chapter 2-section 3 geology notes

Chapter 2- Section 3
Soil Conservation
I.
Why is soil one of Earth’s most valuable natural resources?
Everything that lives on land, including humans, depends
directly or indirectly on soil.
Fertile soil is valuable because there is a limited supply. Less
than 1/8 of the land on Earth have soils suitable for farming.
II.
When is the value of soil reduced?
The value of soil is reduced when soil loses its fertility and
when topsoil is lost due to erosion.
A. Loss of fertility
B. Loss of topsoil
Plant cover can protect soil from erosion.
Wind erosion is another cause of soil loss.
C. Soil loss in the Dust Bowl was caused by over plowing and
drought in the Great Plains.
III. How does conservation plowing help conserve soil?
The previous year’s crop residue protects the soil.
A. Contour plowing- farmers plow their fields along the curves of
a slope t o slow runoff of excess rainfall.
B. Conservation plowing- farmers disturb the soil and plant cover
as little as possible leaving dead weeds and stalks to retain
moisture and to hold the soil in place.
C. Crop rotation- a farmer plants different crops in a field each
year.
Ex: Year one: Corn (absorbs large amounts of nutrients)
Year two: Rye (uses fewer soil nutrients)
Year three: Legumes (restores nutrients)