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Agriculture: Resources

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Title: Agriculture: Resources


1
Agriculture Resources Impacts Themes
  • Agriculture Background
  • Major food resources
  • World food problems
  • Agricultural methods ( Green Revolution)
  • Environmental Impacts ( Huge ! )
  • Damage from energy, water, pesticide use
  • Land degradation / Soil loss
  • Overgrazing / Desertification
  • Solving problems gt Sustainable Agric.

2
1. BackgroundA. Major Food Sources
  • 10 crops provide majority of worlds nutrients
  • Wheat rice provide 25 of calories for the
    world
  • Corn soybean provide 25 of calories
    indirectlyas animal feed
  • Regional differences
  • Potatoes, barley, oats gt cool, moist climates
  • Cassava, sweet potatoes, sorghum gt tropical
    climates
  • Fruits vegetables are regionally important
  • Fish is important primarily in coastal countries

3
  • Meat and dairy distribution highly inequitable
  • Developed countries (20 of world pop.) gt
    consume 80 of worlds meat dairy production
  • gt50 of that meat production occurs in Developing
    Countries
  • This is leading to massive deforestation (e.g.,
    Brazil)
  • Meat prod. requires 3-8x more land than grain
  • 80 of U.S. corn acreage feeds livestock and
    poultry!
  • Modern factory farms for meat production foster
    huge environmental impacts
  • Waste-water lagoons, hormones, antibiotics

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  • Seafood is an important protein source
  • But, cannot solve world hunger problem !
  • Between 1950-1990, world fishing fleet tripled
  • Annual harvest quadrupled (is it sustainable??)
  • Since 1980s, 3/4 of all major world fisheries
    have declined dramatically
  • Enormous costs environmental impacts
  • Catching 70 billion in fish costs 124 billion
  • 1/4 of catch is lost
  • Huge by-catch of non-target fish is also lost

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8
Decline of Ocean Fish Resources
  • Ocean fish harvests have declined for nearly all
    species over the last three decades
  • 13 of 17 world fisheries are considered
    overfished and unsustainable at current harvest
    rates
  • Fish farming has compensated for some of this
    decline, but has enormous environ. impacts

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  • Red King Crab harvest from Bering Sea

11
  • Canadian North Atlantic Fisheries (largest cod
    fishery in the world)

12
  • Cod harvest from Newfoundland (2J, 3K, 3L)

13
  • Change in cod age structure with intense harvest

14
B. World Food Supplies Problems
  • World supply has improved dramatically over past
    century
  • 1950 - 2.5 billion people gt lt 2,000
    cal./person
  • 2005 - 6.5 billion people gt gt 2,500
    cal./person
  • Many regional shortages, however
  • Esp. central, eastern Africa densely pop. areas
    (e.g., India, S.E. Asia see Fig. 7.3)
  • Famines ( Widespread starvation, which cause
    social upheaval economic chaos)
  • Food supply usually has economic, political roots

15
Percentage of population that is malnourished
16
  • Most common problem in LDCs is nutrition
  • 850 million people in LDCs are malnourished(200
    million children)
  • Permanently stunted growth, mental retardation,
    and other developmental disorders
  • Poverty is the greatest threat to food security
  • In poorer countries, people often cannot afford
    to purchase an adequate variety of food
  • Lack sufficient protein (Kwashiorkor)
  • Missing key nutrients (iron)

17
Figure 7.2
18
  • Most common dietary problem in MDCs is
    over-nutrition
  • In NA and Europe, average daily caloric gt
    3,500

19
B. Agricultural Methods (Approaches)
  • Cultivation of crops began 10,000 years ago in
    at least 3 different regions
  • Wheat (Fertile crescent Iraq)
  • Corn (Mexico)
  • Rice (S.E. China)

20
  • 2) Resource-based agriculture
  • Subsistence Agriculture (50 of all croplands)
  • Two main kinds 1) Nomadic herding (subtropical,
    dry)2) Shifting cultivation (tropical forests)
  • 1 farmer feeds family
  • RequiresHigh amount of land, low energy, low
    capital

21
  • Intensive Agriculture (25 of all croplands)
  • Agriculture in China, India, etc. (esp. Rice)
  • 1 farmer feeds several
  • RequiresHigh amounts of labor, low energy,
    low capital

22
  • 3) Demand (Industrialized) Agriculture (25 of
    all croplands)
  • Agriculture in the U. S.
  • Goal ? production per unit of land area
  • ? fertilizer ? pesticides ? irrigation
  • ? mechanization (10 units fossil fuel energy
    1 unit food energy)
  • Includes crop breeding gt high responder
    crops (Fig. 7.26)
  • RequirementsHigh amounts of energy, high
    capital, low labor inputs

23
  • Now includes Genetically Modified Organisms (GMO)
  • GMOs contain DNA possessing genes from unrelated
    species ( transgenic)
  • Most GMOs are produced for pest-resistance (some
    have growth capacity or wider tolerance levels)
  • 60 of all processed foods in U.S. contain
    transgenic products (contain corn, soybean, etc.)
  • Plant breeding could also be used to create new
    crops
  • Most of world food comes from 20 widely grown
    grains and roots and 20 fruits and vegetables
  • At least 3,000 species of plants have been used
    for food at some point in time

24
  • Industrialized Agriculture has created the
    Green Revolution
  • 1900 2000 Huge improvements in yields of
    crops (4x to 8x increase in yields per acre)
  • 25 bushels corn per acre (1900) gt 100
    bushels (with rain) in 2000 200 bushels
    (irrigated Arizona!) in 2000(1 bushel corn /acre
    6.5 grams / sq. meter)

25
  • But at what cost ?
  • 1950 - 1995 2x ? food production
  • Required 5x ? fossil fuels 5x
    ? fertilizers 30x ? pesticides
  • Is this Sustainable ?

26
  • Green Revolution Useful in Tropical
    Countries?Sustainable?

27
2. Environmental Impacts
  • Vary greatly depending upon Agriculture Method
  • In developed countries, 95 of recent
    agricultural growth has been from industrialized
    agriculture practices (? pesticides, fertilizer,
    irrigation)
  • Less land cultivated in NA now than 100 years ago
  • In LDCs damage is widespread from nomadic herding
    (overgrazing), shifting cultivation
    (deforestation), traditional (pollution, other)

28
  • Ecological aspects of agriculture
    damage(Agro-ecosystems differ from natural
    ecosystems)
  • Most agriculture grows monocultures in regular
    arrangements
  • Susceptible to pests, nutrient depletion, etc
  • Ecological simplicity requires great input of
    energy, labor, pesticide to maintain
  • Soil preparation (plowing) often leads to great
    losses (wind water erosion)
  • Often involves growing crops that require
    irrigation

29
a. Impacts from Industrialized Agriculture
  • Farming in industrialized countries is highly
    energy-intensive
  • Mechanization, chemical use, irrigation
  • US food system consumes 16 of total energy use
  • Most foods require more energy to produce,
    process, and transport than they yield in
    calories
  • Much of energy use is exempt from stringent
    pollution laws

30
  • Agriculture accounts for largest single share of
    global water use
  • As much as 80 of water withdrawn for irrigation
    never reaches intended destination
  • Cheap cost encourages over-use gt
  • Waterlogging
  • Salinization

31
  • Fertilizers gt enormous water and air pollution
    problems
  • Adding nutrients via fertilizer usually
    stimulates growth and increases crop yields in
    short term
  • 1950 - Average of 20 kg/ha fertilizer used
  • 2000 - Average of 90 kg/ha fertilizer used
  • Much of the fertilizer runs off and contaminates
    surface waters or percolates into groundwater
  • Fertilizer contributes to air pollution directly
    and indirectly (denitrification)

32
  • Pesticide use produces many undesirable side
    effects (ecological environ. damage) A little
    background, first -
  • Only about 100 species of organisms cause 90 of
    crop damage worldwide
  • Insects are most frequent pests
  • Also includes fungi, plants (weeds), rodents

33
  • Pest control has a long history
  • Mostly involved management !
  • Romans burned fields and rotated crops to reduce
    crop disease
  • Some natural chemicals and biological controls
    used historically
  • Chinese (2,500 years ago) describe mercury and
    arsenic to control pests

34
Synthetic Chemical Pesticides
  • Modern era of pest control began in 1934 with DDT
    (Paul Muller received Nobel prize)
  • Cheap, stable, and easily spread over a large
    area
  • Highly toxic to insects, but relatively nontoxic
    to mammals
  • Pesticide use has increased dramatically since
    WWII (advent of modern chemical industry)
  • 90 of all pesticides are used in agriculture or
    food storage and shipping

35
Types (dont need to know)
  • Inorganic - Broad-spectrum, highly toxic, long
    lasting (e.g., arsenic, copper)
  • Natural Organic (Botanicals) - Generally plant
    extracts (e.g., rotenone, various phenolics)
  • Fumigants - gases (e.g., CCl4, ethylene
    dibromide)
  • Chlorinated Hydrocarbons - Fast acting and highly
    toxic to sensitive organisms (e.g., DDT,
    toxaphene)
  • Neurotoxins in many difference kinds of animals
  • Persistent - tend to biomagnify

36
  • Organophosphates - Extremely toxic to mammals,
    birds and fish (e.g., Malathion)
  • Outgrowth of nerve-gas research
  • Inhibit neurotransmitter enzyme
  • Carbamates - Similar to organophosphates (Sevin)
  • Extremely toxic to bees

37
Pesticide Benefits
  • Disease Control
  • Reduce insects as disease vectors
  • Malaria, Yellow Fever
  • Crop Protection
  • Might reduce pre-harvest post-harvest losses
  • One study 55 loss before pesticide reduced to
    20-30 loss after
  • 3 - 5 saving for every 1 spent on pesticides

38
Pesticide Problems
  • Kills non-target species
  • Up to 90 of pesticides never reach target
  • Kills beneficial insects (pollinators, predators)
  • Pesticide Resistance
  • Resistant members of pest pop. survive pesticide
    treatment and produce more resistant offspring
  • gt Pest Resurgence - (stronger pest emerges)
  • gt Creation of New Pests - (species jump to new
    crop)
  • Pesticide Treadmill
  • Must increase pesticide use b/c of (1) (2)

39
Survival of tobacco bud worms to constant doses
of the insecticide pyrethoid
40
Growth in numbers of damaging pest species with
the advent of chemical pesticides
41
  • Environmental Persistence and Mobility
  • Persistant chemicals (e.g., DDT) move through
    environment
  • Some are stored in body tissues gt
    bioaccumulation
  • Leads to accumulation up the food chain gt
    biomagnification
  • DDT banned from US for over 20 years, but 1000s
    of tons were shipped to LDCs until 2001!

42
  • Human Health Problems
  • WHO estimates 3.5 - 5.0 million people suffer
    acute pesticide poisoning each yeargt 20,000
    deaths/yr3rd worst environ. problem !
  • 2/3 of poisonings are to workers in LDCs
  • Many potential long-term health effects
  • PCBs linked to learning deficiencies in children

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6) Huge wildlife impacts (biomagnification)7)
May not even be effective !
  • 1930 gt 30 of crops lost to pests
  • Management techniques highly effective
  • 1990 gt 37 of crops lost to pests
  • ? Management ???? Chemicals

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Land degradation loss of cropland(Associated
with all kinds of agriculture)
  • Erosion gt 3 million hectares lost / year
  • Salinity gt 1 million hectares lost / year
  • Land development gt 8 million ha lost / year
  • 1 Billion ha of world farmland moderately damaged
    (area the size of China)
  • 300 Million ha seriously damaged
  • 80 million ha seriously damaged in U.S. (perhaps
    1/3 of the topsoil is lost!)

47
  • Land Degradation loss of biological
    productivity (based on potential for that
    specific land)
  • Land is considered degraded when soil is eroded,
    run-off is polluted, or biodiversity is greatly
    diminished
  • Erosion important natural process, both in soil
    formation and soil loss
  • Worldwide, erosion reduces crop production by
    equivalent of 1 of world cropland per year
  • Forces of erosion are wind and water
  • Caused by improper intensive farming
  • Tillage, row crops, no ground cover, no wind
    breaks

48
c. Overgrazing
  • Mostly associated with nomadic herding but also
    affects rangelands of developed countries
  • Overgrazing reduces plant cover and diversity,
    leads to soil erosion and compaction, and
    ultimately reduces range carrying capacity
  • Great reduction in U.S. from 1850 to 2000!
  • Prairies 200 animals / km2 gt 40 / km2

49
d. Desertification
  • Deterioration of lands in semi-arid regions
    associated with poor agricultural practices
  • Affects 1/6 of world population 25 of worlds
    potential agric. Land
  • Caused by improper tillage, overgrazing,
    woodcutting and natural factors (drought)
  • Results in decreased plant cover and diversity,
    soil erosion, and permanent loss of productivity
  • Desertification makes 4 million ha worthless for
    crops or grazing

50
3. Solving ProblemsA. More Green Revolution?
(read p. 154)
  • Technological advances and plant breeding
  • Corn yields increased 5x in last century
  • Genetically Modified Crops?
  • Round-up Ready soybeans were genetically
    engineered by Monsanto Corp.
  • Allows farmers to use Round-up which kills all
    weeds but not the crop
  • The gene has escaped to other soybeans, and now
    Monsanto claims that they own those soybeans, too
  • They won a lawsuit in Canada, and now years of
    soybean breeding by traditional farmers has been
    lost

51
B. Sustainable Agriculture
  • Reduce use of Energy (Fossil fuels)
  • Reduce Soil and Water Degradation
  • Soil Conservation
  • Managing topography
  • Contour Plowing, Strip Farming, Terracing
  • Reduce tillage
  • Maintain ground cover

52
  • Annual row crops cause highest rates of erosion
    because they leave soil bare for much of the year
  • Leave crop residue after harvest
  • Plant cover crops after harvest

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3) Reduce Pesticide Use
  • Old-fashioned Management practices useful
  • Crop Rotation
  • Mechanical Cultivation
  • Flooding Fields
  • Adjusting Planting Times
  • Modern alternative management practices
  • Habitat Diversification
  • Grow Mixed Polycultures (esp. in tropical areas)
  • Growing in Pest-Free Zones

55
  • Biological Controls
  • Predatory / Herbivorous Insects (Parasitic
    Wasps)
  • Hormones / Sex Attractants
  • Bacteria / Viruses

56
Integrated Pest Management
  • Flexible, ecologically-based strategy that uses a
    combination of techniques applied at specific
    times aimed at specific pests
  • Minimizes use of chemical controls
  • Uses economic thresholds to determine when
    economic damage justifies pest control(not
    simply preventative)

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4) New crops from nature!
  • At least 3,000 species of plants have been used
    for food at some point in time
  • Many new or unconventional varieties might be
    valuable food supplies
  • Winged-bean
  • Triscale

59
5) Support Organic Farming (J)
  • O. F. uses no synthetic chemical pesticides
  • Of the 321 pesticides screened, EPA reports 146
    are probable human carcinogens
  • Since 1972, 40 pesticides have been banned
  • Reduce your personal exposure to pesticides
    hormones gt Buy Organic !
  • Consumers can stimulate organic farminggt
    formation of pesticide-free farm zones
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