These are the slides for land use and soil erosion for student to study. You can check more ppt on my profile.

1. Land Use & Soil Erosion
• Agriculture =
dominant land use
• Urban Sprawl =
new land use threat
• Excessive soil
erosion – soil
components moved
to new location due
to water or wind
http://www.metacafe.com/watch/yt-x2CiDaUYr90/u_s_dust_bowl_of_

7. Type of Erosion
• Geological (natural) Erosion
- continuous slow rate of erosion
- 0.02 to 0.25 mm /yr for bare rock
- 2 mm /yr on stable soil surface
• Accelerated Erosion – human-caused
- 10 tons/A/yr
(natural replacement = 0.5 tons/A/yr)
- splash, sheet, rill, & gully erosion
- Dust Bowl (1930s)

8. Rill Erosion

9. Gully Erosion

10. Shelterbelt Program
• Response to Dust Bowl
• 1-5 rows of trees (preferable to have 12)
• ~ 70% reduction in wind speed
• Aesthetics, wildlife habitat, energy
conservation (25% savings)
• Will we repeat History? - removing
windbreaks to gain > field size

15. Managing Soil Erosion
• USDA – 3,000 Soil & Water
Conservation Districts
• Are we controlling soil erosion?
- rate today = rate during 1930s)
- 4 B tons /yr
- mostly on farmland (50% water-
based & 60% wind-based)
- 80% farmland > natural replace. rate

16. Tolerable Soil Loss
• USDA – erosion loss of 1 to 5 tons/A/yr
without impacting crop production
• No scientific basis for this measure

17. Costs of Soil Erosion
• Lower soil fertility / crop production
• Air (dust) & water (sediments) pollution
• Estimates of on-site costs = $27 B/yr
• Estimates of off-site costs = $17 B/yr

18. Erosion Factors (water)
1) Rainfall
• Amount, Intensity, Seasonality
2) Surface Cover (erodibility)
• Soil structure (related to water-stable
aggregates)
water-stable aggregates: material that aids
in soil particles clumping together in
water (e.g., organic matter)

20. Erosion Factors (water)
cover crops:
vegetation
grown
before/after
primary crop
for protection
of soil surface
(e.g., clover,
alfalfa, winter
wheat) –
related to green
manure

21. Erosion Factors (water)
green manure:
plowing under
of cover crop in
order to
increase soil
fertility (N
fixation),
increase organic
matter, reduce
erosion

22. Erosion Factors (water)
3) Topography
• Slope grade and length

23. Controlling Water Erosion of
Soil
clean tillage: crop residues turned into soil
soon after harvest; often fall plow
1) contour farming
2) Strip cropping
3) Terracing
4) Gully reclamation
5) Conservation tillage
6) Cropland Reduction Programs

24. Moldboard Plow

25. Moldboard Plow

26. Contour Farming
• Farming perpendicular to slope (across
slope) -- Jefferson
• Reduces water runoff (65%), erosion,
and siltation
• Link to Strip Cropping

27. Contour-Strip Cropping

29. Corn
Strip Cropping
• Alternate strips of crops across a slope
• Rotate crops (crop rotation), i.e., rotate
strips
• Example:
Corn-Oats-Alfalfa
Oats
Alfalfa

30. Waterways

32. Terracing
• Ancient practice from
mountain cultures
• Create bench-like
steps on steep slopes
• ridge terraces (broad-
base or grass
backslope) – broad
flat steps in slope
• channel terraces – dig
channel across slope;
used in high runoff
sites

33. Channel Terracing

34. Conservation Tillage
• Limit or restrict plowing (tilling) of soil
in order to reduce soil erosion
1) Minimum Tillage – field cultivator &
disc for working top few inches of soil
(vs. moldboard plow turning 6+ inches)
• < 50% of US cropland
2) No Till – field machinery cuts narrow
slit into soil & drops seed; maximal
surface residue; maximal soil protection

35. Minimum Tillage Equipment

36. No-Till Farming
• Pros:
- reduces labor, fuel consumption, soil
erosion
- increases crop yield
• Cons:
- need special equipment
- not universal
- disease & crop pest problems
(herbicide & pesticide use)

37. No Till Equipment

38. No Till

39. No-Till with Crop Residue

40. Pesticides
pesticide: chemical that kills pests (animal
& plant)
herbicide – weeds
insecticide – insects
rodenticide – rodents
Silent Spring – Rachel Carson (1960s)
1960s to present (6X > herbicide)

41. No-Till vs. Minimum Till

43. Alternative Agriculture Systems
conventional farming: agrochemicals, new
crop varieties, bigger equipment
alternative agriculture: use organic,
biodynamic, integrated, low-input or no-
till concepts

44. Alternative Agriculture Systems
organic farming: no agrochemicals;
combats disease/insects via cultural
treatments (e.g., crop rotation, green
manures, compost)
biodynamic farming: use soil preparations
made from animal manure, silica, and
plants
low-input farming: minimize use of
material from outside of farm

45. The Ecology of Farming
• Native communities = dynamic
equilibrium
• Human-altered systems = monocultures,
ecosystem simplification

46. “Cutting-Edge” Agriculture
Integrated Pest Mgt (IPM): limit pesticide
use by combating insect pests with
broad-spectrum (integrated) approach
(e.g., biological, chemical, cultural…)
precision farming: use satellites (Global
Positioning System = GPS) to map
fields and spatial data (crop yield,
fertilizer application); manage smaller
units (i.e., field sub-units)

47. Precision Farming

49. Precision Farming

50. Soil Properties
• comprised of: minerals
organic matter
water
air
• Properties = texture, structure, organic
matter, life, aeration, moisture content,
pH, fertility

51. Soil Texture
• Coarse fraction (rock, gravel) vs. fine-
earth fraction (sand, silt, clay)
• Sand > Silt > Clay
• textural classes (soil texture pyramid,
p.105, fig 6.2)
• adsorption: process of forming chemical
bonds (ionic bonds) between nutrients
(+) and soil (clay -) – relates to
leaching/fertility

53. Adsorption

54. Soil Structure
• arrangement/grouping of soil into
aggregates (or clumps)
• Influenced by “natural” physical factors
(e.g., freezing/thawing, burrowing) and
human alterations (e.g., tilling)
• Affects soil permeability (air & water)
and plant growth (roots)

55. Soil Organic Matter (OM) & Life
• OM = living & dead organisms in soil
• humus: top layer of soil produced via
decomposition; improves structure,
permeability, stability, fertility, habitat
• microorganisms vs. macroorganisms
• mycorrhizae (pl.): “fungus root”
symbiotic relationship between plant &
fungus – nutrient uptake from soil (e.g.,
conifers and fungi)

56. Aeration & Moisture Content
• pore space: space between soil particles
filled with air or water; relation to
structure & texture (sand vs. clay)
• Pore space (aeration/moisture content)
increased by OM
• At soil saturation, all pores filled with
water – correlated with surface runoff
intensity / erosion

57. Soil pH (reaction)
• soil reaction: pH of soil (acid, neutral,
basic) – depends on H+ or OH- ions
• wet & mesic soils – acidic to neutral
• dry soils -- basic
• pH & agriculture
- lime (CaCO3) – Ca+ ions reduce
acidity
- fertilizers (N, P) – with water…
acidic

58. Soil Fertility
• soil fertility: capacity to provide all
nutrients needed for maximum growth
• macronutrient vs. micronutrient
- N vs Fe
• relation to pH
• some nutrient sources:
• fixation, decomposition, animal waste

59. Soil Formation
Five Factors:
1) Climate (temp. & precipitation)
physical & chemical changes in
soil/rock (weathering) – clay, leaching
2) Parent material
- weathering in place or transported
- outwash plain, alluvial, lacustrine,
dunes, tephra

60. Soil Formation
Five Factors:
3) Organisms (macro and micro)
4) Topography – relation to water
movement & soil condition/type
5) Time
*4.5 - 3.5 billion yrs before present(ybp)
* relation to other 4 factors

61. Soil Profile
• soil profile: cross-section view of soil
horizons
• horizon: layers of soil that share
attributes of texture, structure, etc…

62. Soil Profile
Major Horizons:
• O horizon (organic layer)
• A horizon (topsoil, humus, life)
• E horizon (leaching zone)
• B horizon (subsoil, accumulation zone)
• C horizon (parent material, field stone)
• R horizon (bedrock)

63. Water Resources
Water Shortage?
1) Human Population
2) Consumption - ag.,industry,resident
3) Efficiency
4) Distribution Problems
5) Pollution (air, soil, water)

64. Water Cycle?
replacement period: time to complete cycle
(9 days to 37,000 years)
• Unequal distribution of precipitation
- US 102 cm
- MI 81 cm
- Death Valley 4 cm
- Pacific NW 368 cm
• Evaporation & Transpiration

65. Surface Water & Groundwater
• Surface water (lakes, streams)
- may be potable, municipal use
• Groundwater – water infiltrates into soil
• percolation into aquifer (porous soil
stratum of sandstone or limestone)
• zone of aeration: plant roots, capillary
water in pore spaces
• zone of saturation: pore filled from
water table down to bedrock

67. Watersheds
watershed: area drained stream/river
• U.S. Army Corps of Engineers
Flood Control
1) Levees – raise river banks with
earthen/stone dikes
• develop floodplains
• floods prevented, almost
• increase flood severity?

68. Flood Control (cont.)
2) Dredging – removal of sediments
(Corps) – pollutants?
3) Channelization – straightening streams
(NRCS) – floods & drainage,
Everglades
4) Dams – water impoundment – public
works projects
• potable water, irrigation, recreation,
energy
• loss of habitat, evaporation,
sedimentation, $$

69. Dams
- Alqueva Dam (Portugal)
Irrigation water but destroys critical
habitat for Iberian lynx

71. • World’s most
endangered cat
• Less than 600
• Spain & Portugal

72. • Distribution of
Iberian lynx

73. • Know
populations
Iberian lynx

74. • Alqueva Reservoir began filling February 8th 2002
behind
the 96-m-high floodgates
• New proposals to reduce wall height by 13 m leading
to a
reduction of the submersed area from 29,636 ha to

75. Protecting Watersheds &
Floodplains
• watershed protection as proactive &
sustainable flood control mgt.
• USDA, BLM, Army Corps, TVA
• floodplain zoning & Federal Flood
Disaster Protective Act of 1973
• nonstructural flood control

76. Types of Pollution
1) Sediment
2) Inorganic Nutrient
3) Thermal
4) Disease-Producing Microorganisms
5) Toxic Organic Chemicals
6) Heavy Metals
7) Organic Wastes

77. Managing Pollution
pollution control: (output control)
manage pollutant post hoc
- pollutant dispersion
pollution prevention: (input control)
avoid pollution a priori

78. 1) Sediment Pollution
- linked to soil erosion /poor land use
Sources: agriculture, logging,
construction, strip mines
Costs: $1 million per day in US
clog irrigation canals, hydro-
electric turbines, harbors, life of dams
shortened
- carries toxins
- turbid water & sedimentation
“kills” coldwater fish/bivalve
habitat

79. Controlling Sediment Pollution
- input control includes:
conservation tillage
contour-strip farming
shelter belts
terracing
cover crops/increase OM
- output control includes: $$$$$
sediment filtration systems (artificial &
natural)
dredging

80. 2) Inorganic Nutrient Pollution
- aquatic systems require certain chemical
elements to exist & support life
- includes C, O, N, H, P among others
- N & P often are limiting factors because
of their reduced abundance;
- P > N in importance as limiting factor
- > N & P = > productivity of aquatic
system

81. Lake Productivity Gradient
1) oligotrophic: nutrient-poor lake
- low productivity
- low plant/animal biomass
- e.g., Lake Superior = young lake
2) mesotrophic: moderate nutrient base
- swimming, fishing
3) eutrophic: nutrient rich
- dense algal blooms
- reduced dissolved oxygen, diminished
fishery

82. 3) Thermal Pollution
- increase temperature of aquatic system
- Harmful effects:
- reduced dissolved oxygen
- reduced fish reproduction
- spread of disease
- Benefits:
- increase growth rate of some fish
- heating homes
- Use of coolant towers

83. 4) Disease-Producing Organisms
- infectious organisms introduced to water;
cholera, typhoid fever, dysentery, polio,
Cryptosporidium
- better sanitation & water treatment can
reduce disease
e.g., chlorination for bacteria and
oxygenation for enteric disease
(intestine-dwelling; anaerobic)
- coliform bacteria count: index of
microorganism-based water pollution
coliform = usually harmless bacteria in
human gut

84. 5) Toxic Organic Chemicals
- Carbon-based compounds; synthetic
derivatives such as Volatile Organic
Compounds (VOCs) = toluene
- Synthetic Organics = resist
decomposition & therefore persistent
- Disrupt normal enzyme function in
organisms; interfere with normal
chemical reactions in cells

85. Water Pollutants
1) Review Table 11.4, p 268
2) Your choice, pick 1 of the pollutants
and,
a) be able to name it;
b) provide an explanation of its use;
c) indicate its source & its prevalence in
the Great Lakes; and
d) explain its effects on human health

86. 6) Heavy Metals
e.g., lead, mercury, arsenic, cadmium
(fundamental chemical elements)
- Mines & contaminated groundwater
- Mines & tailings (Clarks Fork of
Yellowstone)
- interfere with normal enzyme function
- lead contamination (soil & water) from
paint & plumbing pipe (solder)
- mercury contamination (methyl Hg in
air & water) from industry; in muscle
tissue

87. 7) Organic Waste: reduce available oxygen
- decomposition of wastes by bacteria uses
oxygen; release of nutrients -- cyclic
- Oxygen-demanding organic wastes
biological oxygen demand (BOD): index of
amount of organic matter in water
sample; indexed via rate of oxygen use
by bacteria
- aquatic indicator species (bio-sentinels
or bio-indicators) – also application to
other pollutants (may flies, trout,
bullheads, carp, sludge worms, mink)

88. 7) Organic Waste: reduce available oxygen
- decomposition of wastes by bacteria uses
oxygen; release of nutrients -- cyclic
- Oxygen-demanding organic wastes
biological oxygen demand (BOD): index of
amount of organic matter in water
sample; indexed via rate of oxygen use
by bacteria
- aquatic indicator species (bio-sentinels
or bio-indicators) – also application to
other pollutants (may flies, trout,
bullheads, carp, sludge worms, mink)

89. Eutrophication

90. Gulf of Mexico - Watershed

91. Gulf of Mexico - Watershed
• hypoxic zone
• dissolved oxygen
concentration less than
2 mg/L, or 2 ppm

92. Gulf of Mexico - Watershed
• 22,000 km2 in mid-
summer
• Size of New Jersey or
the states of Rhode
Island and Connecticut
combined

93. Gulf of Mexico - Watershed