Agriculture: Resources

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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.

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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

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• 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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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

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

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

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• Change in cod age structure with intense harvest

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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

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Percentage of population that is malnourished
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• 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)

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

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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)

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• 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

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• 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

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• 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

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• 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

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• 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)

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

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• Green Revolution Useful in Tropical
  Countries?Sustainable?

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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)

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• 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

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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

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• 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

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• 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)

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• 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

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• 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

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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

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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

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• 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

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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

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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)

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Survival of tobacco bud worms to constant doses
of the insecticide pyrethoid
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Growth in numbers of damaging pest species with
the advent of chemical pesticides
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• 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!

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• 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!)

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• 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

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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

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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

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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

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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

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• 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

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

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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

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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