1. AP Environmental Science
Ch 14
Food Resources
© Brooks/Cole Publishing Company / ITP

2. Soil

3. Soil Formation Soils develop in response to: Climate Parent Material
Topography
Time
Living and dead organisms

4. Climate Climate (temperature and moisture) affect:
Weathering processes
Microenvironmental conditions for soil organisms
Plant growth
Decomposition rates
Soil pH
Chemical reactions in the soil

5. Destructional -Weathering Landscapes broken down by chemical & physical processes & erosion
Includes temperature changes (freezing and thawing, thermal expansion), crystal growth, pressure, plant roots, burrowing animals
Causes disintegration of parent material and facilitates chemical weathering
Chemical
Always in water
Includes hydration, hydrolysis, oxidation, reduction, carbonation

6. Parent Material
Parent material- refers to the rock and minerals from which the soil derives.
The nature of the parent rock has a direct effect on the soil texture, chemistry and cycling pathways.
Parent material may be native or transported to area by wind, water or glacier.

7. Topography
Topography- physical characteristics of location where soil is formed.
Drainage
Slope direction
Elevation
Wind exposure

8. Time Soil horizons Soil profile Humus Bedrock Immature soil
O horizon
Leaf litter
A horizon
Topsoil
B horizon
Subsoil
C horizon
Parent
material
Mature soil
Young soil
Bedrock
Immature soil

9. Organisms in Soil Bacteria—fix nitrogen
Worms and insects-aerate and fertilize the soil
Trees, plants, etc. provide stability against erosion and organic material
Humus--decomposed, organic matter
Decreases erosion and retains water
Provides nutrients
Improves porosity so makes root growth easier.
Temperate deciduous forests and grasslands have very rich soil

10. Increasing percentage sand
Soil Properties
100%clay
Increasing
percentage silt
percentage clay 20 40 60 80
100%sand
100%silt
Increasing percentage sand
Water
High permeability
Low permeability
Fig , p. 224
Infiltration/permeability
Porosity
Leaching
Texture pH
Etc.

11. Soil Properties Texture Nutrient Infiltration Water-Holding Aeration
Capacity Capacity
____________________________________________________
Clay Good Poor Good Poor
Silt Med Med Med Med
Sand Poor Good Poor Good
Loam
(mix) Med Med Med Med

12. Soil Chemistry Acidity / Alkalinity – pH
Most abundant element in soil is oxygen in the form of SiO2
Major Nutrients
Nitrogen
Phosphorus (phosphates)
Potassium (potash)

13. Acidity / Alkalinity – pH
pH directly affects the availability of plant food nutrients
Too acidic or basic will not:
Allow compounds to dissolve
Allow presence of certain ions
Best if between pH 6 – 8 (except for acid loving plants)
Too acidic, add ground limestone
Too basic, add organic material like steer manure

14. Nitrogen Content Importance
N is component of proteins and DNA
Stimulates growth and produces rich green color
Quality and protein content of fruit
Taken up by plant as NH4+ (ammonium) and NO3- (nitrate)
Replenished naturally by:
Rhizobacteria on legume roots (beans, alfalfa) that fix nitrogen gas for plant use
Fertilizer from manure or inorganic sources

15. Phosphorus for Growth Abundance causes:
Strong root system
Increases seed yield and fruit development
Parts of root involved in water uptake (hair)
Major role in transfer of energy--ATP
Taken up by plant as H2PO4- and HPO4-2
Fertilizer is made from rock phosphate
Banned in laundry detergents in some states due to eutrophication of lakes from runoff.—IN is one

16. Potassium Content “Potash” Important in vigor and vitality of plant
Carries carbohydrates through the plant
Improves quality of fruit
Promotes vigorous root systems
Offsets too much N
Found naturally in feldspar and micas

17. Improving Soil Nutrients
Organic fertilizer- from plant and animal materials (i.e. green manure, cow manure)
Commercial inorganic fertilizer- produced from various minerals.
Humus
Crop rotation-by planting crops that use a lot of nutrients, like corn, and the next year plant those that return nutrients, like legumes.

18. Inorganic Commercial Fertilizers
Trade-Offs
Inorganic Commercial Fertilizers
Advantages
Disadvantages
Easy to transport
Easy to store
Easy to apply
Inexpensive to produce
Help feed one of every
three people in the
world
Without commercial
inorganic fertilizers,
world food output could
drop by 40%
Do not add humus to soil
Reduce organic matter
in soil
Reduce ability of soil to
hold water
Lower oxygen content of
soil
Require large amounts of
energy to produce,
transport, and apply
Release the greenhouse
gas nitrous oxide (N2O)
Runoff can overfertilize
nearby lakes and kill fish

19. Food Production
Generalized locations of the world’s principal types of food production.
Fig. 12–2
© Brooks/Cole Publishing Company / ITP

20. Food Production Food systems
Croplands-mostly produce grain; provide 77% of the worlds food
Rangelands and Confined Animal Feeding Operations (CAFOs)-produce meat; provide 16% of world’s food
Ocean fisheries-produce 7% of worlds food
14 plants & 8 terrestrial animal species supply approximately 90% of the world’s caloric intake
Wheat, rice, and corn provide more than ½ the calories humans consume-annuals!

21. Food Production
Technological advances caused a huge increase in food production due to growing/raising plants and animals closer together than ever before
Competition within species minimized
For plants: farm machinery, irrigation, inorganic fertilizers, pesticides, high yield varieties
For animals: antibiotics, food additives, growth hormones, enclosed animal pens.

22. Figure 14-3 Page 276 Natural Capital Croplands Ecological Services
Economic
Services
Ecological Services
Economic Services
Help maintain water flow and
soil infiltration
Provide partial erosion protection
Can build soil organic matter
Store atmospheric carbon
Provide wildlife habitat for some
species
Food crops
Fiber crops
Crop genetic
resources
Jobs
• Help maintain water
flow and soil infiltration
• Provide partial erosion
protection
• Can build soil organic
matter
• Store atmospheric
carbon
• Provide wildlife habitat
for some species
• Food crops
• Fiber crops
• Crop genetic
resources
• Jobs

23. Types of Food Production
Industrialized agriculture- high input, high output form of farming, usually consisting of monocultures made possible b/c of cheap energy OIL
Large amounts of fossil fuel, water, commercial fertilizers, and pesticides.
10 units nonrenewables/1unit food (on table)
Mostly used in developed countries
Plantation agriculture- Cash crops in the tropics

24. Green Revolutions First “Green” Revolution since 1950
Haber-Bosch process was developed, which fixes nitrogen, a limiting factor to plant, and therefore animal, growth.
Process uses fossil fuels
Increased yields per unit area of cropland.
Diverse family farms became monocultures of GM, high–yield crops
Large inputs of fertilizer, pesticides, and water
Increased the intensity and frequency of cropping.
2nd Green Revolution since 1967
Introducing fast-growing, higher yield dwarf varieties of rice and wheat to developing countries

25. Types of Food Production
Traditional agriculture- low input form of farming
1 unit nonrenewable resource input =1unit food
Traditional subsistence- human labor & draft animals to produce enough crops or livestock for a family’s survival.
Shifting cultivation and nomadic livestock herding

26. Types of Food Production
Traditional intensive-increased inputs of labor, fertilizer, and water to achieve higher yields for sale.

27. Growing Techniques Growing techniques in traditional agriculture
Interplanting – growing several crops on the same plot so diversity reduces water loss and risk due to misfortunes
1. Polyvarietal cultivation – planting several varieties of the same crop.
2. Intercropping – two or more different crops grown at the same time on a plot.

28. Growing Techniques 3. Agroforestry-crops and trees grown on same plot.
4. ***Polyculture – different plants that mature at different times
Low input, less fertilizer and water due to varying root systems, wind and water erosion protection, less insecticide higher yields!
Interplanting video clip

29. Soil Erosion and Degradation
Soil erosion- movement of soil components, especially litter and topsoil, from one place to another.
Makes soil less fertile and less able to hold water
Takes typically 200–1000 years to form 2.5 centimeters (1 inch) of topsoil
Eroding faster than it forms in about one–third of the world's cropland
In the U.S. is being eroded 16x faster than it is being formed
Moving water is the prime cause of erosion.

30. Soil Erosion and Degradation
Major areas of the world are threatened by serious soil erosion.

31. Soil Erosion and Degradation
1930s- a combination of drought and poor soil conservation led to severe wind erosion of topsoil in what is known as the Dust Bowl of the Great Plains.
1935 Soil Erosion Act- SCS (Soil Conservation Service) promoted sound soil conservation practices
Soil Erosion Video

32. Soil Erosion and Degradation
Causes:
Overgrazing
Deforestation and devegetation
Surface mining
Poor irrigation techniques
Salt buildup
Farming on unsuitable terrain
Soil compaction by farm machinery.

33. Soil Erosion and Degradation
Problems with irrigation
Salinization- results in irrigated cropland where salts build up to levels that decrease yields or prevent cultivation.
Waterlogging- results when excess irrigation water raises the water table and lowers crop productivity.

34. Soil Conservation
Soil conservation involves reducing soil erosion and restoring soil fertility.
Conservation–tillage farming- use of special tillers or no–till methods that inject seeds, fertilizers, and herbicides into unplowed soil. Soil not disturbed over winter in temperate zones.
Windbreaking- use of vegetation surrounding a plot of land to reduce wind erosion
Use of cover crops during the off-season (i.e. winter wheat can be grown in some areas.)
Stalks and stem remains of harvest can be left in field over winter

35. Soil Conservation Other methods: Erosion Control video clip
Terracing- protects steep slopes
Contour farming- plowing at right angles to the slopes
Strip cropping maintains strips of different vegetation between crops
Alley cropping grows crops between rows of trees
Agroforestry
Erosion Control video clip

36. CONTOUR PLANTING
AND STRIP CROPPING
TERRACING
WINDBREAKING
ALLEY CROPPING
AGROFORESTRY

37. World Food Supply
Enough food is produced to feed all people, but it is unevenly distributed.
LDCs are undernourished or malnourished
Undernutrition- can’t meet basic energy needs
Malnutrition- energy needs met, but not enough proteins and vitamins (“mal” = bad)
Still growing exponentially
MDCs are over nourished and wasteful.
More grain is going to livestock and cars, so the price of grain b/t roughly tripled, setting record highs.
Recently been buying or leasing lands in LDCs to grow crops

38. World Food Supply
Carrying capacity of Earth is reliant on both food and freshwater supplies
Our food supply is based on limited freshwater, as well as nonrenewable fossil fuels.
Many tracts of land are being use to grow corn or sugar cane for fuel instead of food.
The number of people Earth can support depends on the following:
Cultural carrying capacity/person (habits, diet, etc.)
Sustainability of future food production
Percentage of the population eating meat (higher trophic level…remember 2nd law of thermodynamics!)

39. World Food Supply Per capita food production slowing Freshwater crises
Salinization of soil and erosion
Drought and flooding due to climate change
World population increasing
Increasing demand for food in industrializing countries, especially meat
Degradation and loss of cropland
Decrease in grain stores which have been kept since ancient times

40. Increasing Food Production?
To increase crop yields
Genetic engineering
Raise the share of photosynthetic product in the seed
Develop strains of plants resistant to disease, insects, and drought.
Increase inputs of water, fertilizer, and pesticides
Eventually these additions produce no additional increase in crop yields.

41. Genetically Modified Food and Crops
Trade-Offs
Figure Page 292
Genetically Modified Food and Crops
Projected
Advantages
Projected
Disadvantages
Need less fertilizer
Need less water
More resistant to insects,
plant disease, frost, and
drought
Faster growth
Can grow in slightly salty
soils
Less spoilage
Better flavor
Less use of conventional
pesticides
Tolerate higher levels of
pesticide use
Higher yields
Irreversible and
unpredictable genetic
and ecological effects
Harmful toxins in food
From possible plant cell
Mutations
New allergens in food
Lower nutrition
Increased evolution of
Pesticide-resistant
Insects and plant
disease
Creation of herbicide-
Resistant weeds
Harm beneficial insects
Lower genetic diversity

42. Increasing Food Production
Investigate new types of food
Cultivation of less widely known plants that may be found in seed banks or elsewhere
Cultivation of perennial plants reduce inputs of water, fertilizer, and energy – reduce soil erosion
Yummy insects: microlivestock

43. Increasing Food Production
Cultivating more land
Clear tropical forests
Nutrient–poor soils will likely make agriculture unsustainable
Removal of valuable carbon sink
Loss of biodiversity
Irrigate arid lands
Expensive dams
Depletion of groundwater
A major economically profitable and environmentally sustainable expansion of cropland is unlikely over the next few decades.

44. Turning to the Oceans Fisheries and fish harvests
11 of the world’s 15 major oceanic fishing areas have been fished at or beyond their estimated maximum sustainable yield for commercially valuable species and are in a state of decline.
Why?
Growing demand for seafood
Efficient, large–scale industrial fishing fleets
Degradation and destruction of coastal wetlands
Pollution of coastal waters

46. Turning to the Oceans Aquaculture—the Blue Revolution
Fish farming and fish ranching
Produce high yields in a small volume of water
Increase yields by crossbreeding and genetic engineering
Supplies 1/3 of the commercial fish harvest
Aquaculture – the limitations
Conversion of coastal wetlands to fish farms
Genetic pollution of natural fish populations by escapees
Contamination of nearby waters with waste and chemicals

47. Environmental Impacts
General considerations
World population increase will demand greater food production
Further application of green revolution techniques will increase food production, but these techniques have limitations and environmental consequences
Industrialized agriculture has a greater harmful impact on air, soil, water, and biodiversity resources than any other human activity!

48. Environmental Impacts
Fig. 12–11 a and b
© Brooks/Cole Publishing Company / ITP

49. Environmental Impacts
Fig. 12–11 c and d
© Brooks/Cole Publishing Company / ITP

50. Environmental Impacts
Fig. 12–11 e
© Brooks/Cole Publishing Company / ITP

51. Environmental Impacts
Focus on meat
More than 1/2 of the world’s cropland is used to produce livestock feed
Overgrazing is the major cause of desertification of arid and semi–arid lands
Cattle produce the GHG, methane (CH4) primarily when belching, which is 25X’s more potent GHG than CO2
Cattle in feedlots require large doses of antibiotics: 70% of all U.S. antibiotics in U.S. goes in meat production
50% of all water withdrawn from rivers and aquifers used for meat production each year.
1 cow’s waste = 16 humans’!
Meatrix Video--5 min

52. Kilograms of grain needed per kilogram of body weight
Beef cattle
Pigs
Chicken
Fish (catfish
or carp) 7 4
2.2 2
© 2004 Brooks/Cole – Thomson Learning

53. The Ultimate Question
Do we feed people at the expense of the environment?
Worldwide we already have enough food, it just has to be distributed evenly
Many cases in scientific research have shown that when food sources increase, so do species’ populations…positive feedback loop…possibly furthering environmental damage.
Humans have one thing that other species do not: RESTRAINT
Possibly turn to population controls instituted with promised food aid?
In the meantime, people are dying and this can’t be ignored.

54. Sustainable Agriculture
Some ways to reduce environmental impact
Reduce water waste in irrigation
Emphasize biological pest control and integrated pest management
Increase use of organic fertilizers
Increase use of soil conservation techniques.
Increase use of polyculture: less water, fertilizers, herbicides, insecticides, and greater biodiversity.
Eat less meat
Bill Nye: Dinner (14 min)

55. Sustainable Agriculture
Solutions
Sustainable Agriculture
Increase
Decrease
High-yield polyculture
Organic fertilizers
Biological pest control
Integrated pest
management
Irrigation efficiency
Perennial crops
Crop rotation
Use of more water-
efficient crops
Soil conservation
Subsidies for more sustainable farming and
fishing
Soil erosion
Soil salinization
Aquifer depletion
Overgrazing
Overfishing
Loss of
biodiversity
Loss of prime
cropland
Food waste
Subsidies for unsustainable
farming and fishing
Population growth
Poverty

56. Sustainable Agriculture
What Can You Do?
Sustainable Agriculture
Waste less food
Reduce or eliminate meat consumption
Feed pets balanced grain foods instead of meat
Use organic farming to grow some of your OWN
food
Buy organic food
Compost your food wastes

57. Pesticides: Types and Uses
Pest – any species that competes with humans for food, invades lawn and gardens, destroys wood in houses, invades ecosystems, causes disease, or is a nuisance.
100 species of plants (weeds), animals (mostly insects), fungi and microbes (infect plants and animals) cause 90% of damage to the crops we grow

58. Geographic range of five major pests in the lower 48 state of the United States

59. Types of Pesticides
Pesticides- chemicals used to kill undesirable organisms
Insecticides- insect killers
Herbicides- plant killers
Fungicides- fungus killers
Nematocides- round–worm killers
Rodenticides- rat and mouse killers

60. Types of Pesticides 1st generation pesticides
Mostly natural substances obtained from plants
Examples: pyrethrum and rotenone
2nd generation pesticides
Synthetic organic chemicals developed from fossil fuels since 1945
DDT
Broad–spectrum- toxic to many species
Selective- toxic to a narrowly defined group
Persistent- remain in the environment for an extended period of time

61. Use of Pesticides Most pesticide use is in developed countries
It’s use started after WWII as a way to get rid of extra toxic substances used during the war.
90% of insecticides and 80% of herbicides applied to crops in the U.S. are used for growing cotton and corn
U.S. lawns are doused with 10x more pesticides/hectare than cropland

62. The Case for Pesticides
Pesticides kill disease–carrying insects
Until the plasmodium that causes malaria became resistant, DDT was commonly used to combat it.
Pesticides increase food supplies and lower costs
Approximately 55% of the world’s food supply is lost to pests
Pesticides increase profits for farmers
Use of pesticides increases crop yields
Pesticides work faster and better than alternatives
New pesticides are used at lower rates

63. The Case Against Pesticides
The pesticide treadmill
1) Use of pesticides on a crop
2) Pests develop genetic resistance to pesticides
3) Dosage of pesticides increased or new pesticide is used
4) Pests develop genetic resistance to pesticides
5) repeat

64. Number of genetically resistant insect species
600
500
Neonicotinoids
(1995)
400
Number of genetically resistant insect species
Pyrethroids (1978)
300
Carbamates (1972)
200
Organophosphates (1965)
100
DDT/cyclodienes (1946)
1950
1960
1970
1980
1990
2000
Year

65. The Case Against Pesticides
Broad-spectrum pesticides affect many species other than the target.
Agricultural workers who are poisoned.
Waterway and drinking water pollution due to runoff.
Bioaccumulation of persistent pesticides
Biomagnification

66. Other Methods of Pest Control
Genetic engineering
Development of disease and pest resistant crop varieties
Could reduce the number and quantity of pesticides needed to protect crops
Potential limitations
Eventual pest adaptation to new crops
Resistance factors may be toxic to beneficial insects and other animals

67. Case Study: Bt Gene
Bt Gene video 10min

68. Other Methods of Pest Control
Biopesticides- plant toxins synthesized for mass production
Hormones- pheromones to lure pests into traps or other hormones to control maturation
Birth control- release of sterile males

69. Hormones
Hormones
Example: For normal insect growth, development, and reproduction to occur, certain juvenile hormones (JH) and molting hormones (MH) must be present at appropriate stages of the life cycle.
If applied at the proper time, synthetic hormones disrupt the life cycles of insect pests and control their population.

70. Other Methods of Pest Control
Integrated pest management- each crop and its pests are evaluated as parts of an ecological system.
A control program is developed that includes a mix of cultivation, biological and chemical control methods.
1) Crops monitored for damaging levels of pests
2) Biological control methods used
3) Small amounts of diverse chemicals used to prevent development of resistance and to avoid killing beneficial insects and predators

71. Integrated Pest Management
The goal: to keep each pest population just below the size at which it causes economic loss.

72. Case Study: U.S. Cotton Eradication Program
Boll weevils feed on cotton buds and flowers
Traditionally this plant required 41% of all pesticides and a tremendous amount of water.
USDA Boll Weevil Eradication Program has been touted as one of the most successful integrated pest management systems to date.
1st year numerous malathion pesticide treatments and stalks are plowed to the ground to prevent winter inhabitation
Years 2-5 use of pheromone traps and spraying only in fields where weevils are detected.
Eradication Program