1. Lokhesh
Mithuna Maran
Mogan Prasad
Mohamed
Abbas
Nandhakumar
Nandhini
Priyanka
E.V.S Project
B.Arch (1st year)
Section ‘B’

8. Soil, a
limited
resource we
depend upon,
but take for
granted

9. Soil Erosion
 What causes soil erosion?
 How serious of a problem is it?
 Good news and bad news from the U.S.
 What is desertification?
 How do salts degrade the soil?

10. CAUSES OF SOIL EROSION
Wind WHY
CARE
about
Water #1 soil
erosion?
People

12. Impacts of Soil Erosion
 Loss of soil fertility
 Sediment runoff causes
problems in surface water
(pollution, clog ditches, boat
channels, reservoirs)
 #1 source of U.S. water
pollution
 Renewable only on LONG
timeframes (200-1,000yrs. for 1
inch)

13. Soil Erosion
On Ag. land in U.S. today, soil is eroding 16 times faster
than it is created

14. Global Soil Erosion
Areas of serious concern
Areas of some concern
Stable or nonvegetative areas
Fig. 14-7 p. 280

15. Causes of Desertification
Overgrazing
Deforestation
Erosion
Salinization
Soil Compaction
Natural Climate Change

16. World Desertification
Fig. 14-9 p. 282

17. Desertification: causes and consequences.
•Occurring on 1/3 of world’s land

18. SALINIZATION
1. Irrigation
water contains
small amounts
of dissolved
salts
2. Evaporation
and
transpiration
leave salts
behind
3. Salt builds up
on soil

20. Reducing and Cleaning Up Salinization
Reduce irrigation
Switch to salt-tolerant crops
Flush soils
Not growing crops for 2-5 years
Install underground drainage

21. Soil Degradation on Irrigated Land
 Salinization Evaporation Evaporation
Transpiration
 Waterlogging
1. Precipitation and
irrigation water
percolate
downward
2. Water table rises Waterlogging
3. Bad for roots
Less permeable
clay layer
Fig. 14-11 p. 283

24. What controls soil productivity?
 Water -infiltration, drainage, storage
 Nutrients/toxins (12/17)
 Gas Exchange -CO2 out, O2 in
 Strength/rooting volume
 Waste Disposal
 Seed/seedling nursery

25. Where is the best soil?

26. Where are the productive soils?
We see what we know. The more we know, the
more options we realize we have w/ the world’s
soils.

27. What are some threats?
 Finite arable land: 1.1 billion hectares
 1961 0.32 ha/p; today 0.15 ha/p; 2050 0.12 ha/p
 Erosion – today 12-40 Mg/ha 30% agricultural
lands irreversibly damaged.
 Desertification – e.g., 27% China affected w/ new
2500 km2/yr.
 Salinization- affects 20% of world’s 250+ million
hectares of irrigated lands.
 Contamination w/ heavy metals.
 Urbanization and other competing uses.
 Problematic off-site issues & competing uses.

28. Threats? Think little things.
 Compaction or loss of porosity.
 Loss soil organic matter.
 Loss CEC other buffering potential. Doolittle Prairie –
e.g., 10% reduction
in pore volume
= 152 m3/ha
= 2200 ft3/ac
-less gas exchange,
water storage, root
volume; poorer
nursery.
-water quality &
quantity, air quality

29. Soil Conservation
 What is soil conservation and how does it work?
 What are some methods for reducing soil erosion?
 Inorganic versus organic fertilizers

30. Soil Conservation
Involves many ways of reducing soil erosion and restoring
fertility to soil.

31. Conventional Tillage
Farmers plow the land and then
break up and smoothes soil to
make a planting surface
 Leaves soil vulnerable to
erosion
 Midwest tillage often down in
fall (winter bare)

32. Conservation Tillage
Disturbing the soil as little as
possible while planting crop
 Not tilling over winter
 Planting without disturbing
soil
 Special equipment “inject” soil
with seed, fertilizer etc.
 In 2003 45% of U.S. farms

35. Terracing
Used on
steep
slopes
Reduces
erosion
and water
loss

37. Contour
planting
Planting
crops in rows
across the
slope
Strip
Cropping
Cover Crops: can be planted Alternating
right after harvest to hold onto crops from
soil during winter row crops
and crops
that

39. Alley Cropping: several cops planted together in rows
(alleys) Increases shade (less water) Provide
windbreaks

40. Windbreaks

41. SOIL RESTORATION
 Organic fertilizer
 Animal manure
 Compost
 Crop rotation
 Commercial inorganic fertilizer

42. Organic Fertilizer
Has decreased in the U.S.
due in part because
most farmers no longer
raise livestock and it
costs too much to
transport
 Poop Factory and
Phillies Soil
 Inorganic fertilizers
have taken off

43. Inorganic Fertilizers
Nitrogen, Phosphorous,
Potassium
 Grown in usage
worldwide
 Credited with increasing
crop yields (1/4 of world
crops)
 W/o could only feed 2-3
billion people
 Many problems
associated (see next
slide)

44. “Conservation is a state of harmony between men and
land.”
- Ibid.
“What greater grief than the loss of one's native
land.”
-Euripides
“The land belongs to the future”
-Willa Cather