This document discusses soil as an important resource that needs to be conserved and protected from threats like depletion and salinization. It provides examples of methods for preventing soil erosion, including windbreaks, contour farming, terraces, strip cropping and no-till farming. Terrace farming can increase the amount of usable land for farming by making previously steep slopes farmable. It estimates it would take 50 years to naturally form 10 centimeters of new topsoil based on a rate of 2 millimeters per year.

1. Weathering,
Soil, and Erosion
12.4 Soil as a resource

2. Know
• soil fertility
• soil depletion
• salinization

3. Understand
• Soil is an important resource that can be
conserved and protected.

4. Do
• Describe ways is which human activity
threatens soil fertility.
• Summarize soil conservation methods
that reduce soil erosion.

5. 4. Nutrients return to
soil
3. Plants die and 1. Soil contains
decompose in the ground nutrients
2. Natural vegetation 5. Crops use
uses nutrients nutrients
6. Crops are
harvested
7. Fertilizers must be added to
replace nutrients.

6. List and briefly describe three
methods of preventing erosion of
farmland.
• Windbreaks: planting belts of trees along
field edges. Contour farming: planting
crops in rows parallel to land contours.
Constructing terraces: flattening sloping
areas by forming terraces. Strip cropping:
alternating a crop that leaves bare ground
with a crop covers the ground. No-till
farming: doing planting, fertilizing, and
weed control at the same time.

7. 12.4 #1. Describe some ways
to prevent soil depletion.
• #1. Allowing fields to lay
fallow, Allowing a crop to
decompose on the soil, and
changing the kind of crop
grown on a field from year to
year.

8. Uruguay
Pointe-de-Rivere-
du-Loupe, Canada
Colorado

9. #2. How and where does
salinization occur?
• #2. Salinization occurs in
desert areas when irrigation
water evaporates rapidly and
minerals dissolved in the
water are left behind on the
soil surface.

10. Montana
California
South Africa

11. #3. Describe at least three methods
that can be used to protect a field
from wind or water erosion.
• #3. Windbreaks: planting belts of trees along field
edges.
• Contour farming: planting crops in rows parallel to
land contours.
• Constructing terraces: flattening sloping areas by
forming terraces.
• Strip cropping: alternating a crop that leaves bare
ground with a crop covers the ground.
• No-till farming: doing planting, fertilizing, and
weed control at the same time.

14. New Zealand

15. Corn
Oats & radish

16. #4. Terrace farming is used to reduce erosion.
Explain how terrace farming could also increase
the amount of land available for farming.
• #4. Some slopes may be too
steep for use in farming. By
creating terraces on these
slopes, unusable land becomes
farmable land.

17. Laos
Peru

18. #5. One estimate for the rate at which natural processes can
replace topsoil that has been eroded is about 2 millimeters per
year. At this rate, how long would it take to form 10 centimeters of
new topsoil? Show your work.
• 2 mm X 1 cm = 0.2 cm
#5. 1 year 10 mm 1 year
• 10 cm X 1 year = 50 years
0.2 cm