Environmental Impacts of Conventional Agriculture

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Environmental Impacts of Conventional Agriculture

• October 22, 2004

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Fundamental Differences Between Conventional
(Modern) and Traditional Agriculture

• Conventional agriculture is highly LINEAR,
  traditional agriculture is highly CYCLICAL.
• Conventional agriculture is based on maximizing
  the output of a narrow range of species.
  Traditional agriculture is based on achieving
  reasonable yields of a DIVERSITY of species.
• Conventional agriculture is ultimately
  UNSUSTAINABLE because it is based on capital
  depletion and massive additions of external
  inputs (e.g. energy, water, chemicals).
  Traditional agriculture is designed to live off
  of the interest.

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Summary Quotes on the Impacts of Conventional
Agriculture (source Horrigan, Lawrence and
Walker, 2002)

• Industrial agriculture views the farm as a
  factory with inputs (such as pesticides, feed,
  fertilizer, and fuel) and outputs (corn,
  chickens, and so forth). The goal is to increase
  yield (such as bushels per acre) and decrease
  costs of production.
• Industrial agriculture depends on expensive
  inputs from off the farm (e.g. pesticides and
  fertilizer) many of which generate wastes that
  harm the environment it uses large quantities of
  nonrenewable fossil fuels and it tends toward
  concentration of production, driving out small
  producers and undermining rural communities.

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Summary Quotes (cont)

• The following environmental and public health
  concerns are associated with the prevailing
  production methods
• 1) monocultures are eroding biodiversity among
  both plants and animals
• 2) synthetic chemical pesticides and fertilizers
  are polluting soil, water and air, harming both
  the environment and human health
• 3) soil is eroding much faster than it can be
  replenished, taking with it the lands fertility
  and nutrients that nourish both plants and those
  who eat them
• 4) water is consumed at unsustainable rates in
  many agricultural areas and
• 5) massive inputs of fossil fuel energy are
  required to keep the agricultural system going.

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Major Environmental Concerns of Conventional
Agriculture

1. Heavy reliance on chemical pesticides
   (insecticides and herbicides) to control damaging
   insects and weeds.
2. Intensive soil manipulation/application of
   chemical fertilizers to maintain crop
   productivity.
3. Heavy reliance on external inputs of energy and
   water.

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Heavy Reliance on Chemical Pesticides to Control
Insects and Weeds

• WHY do we do it this way?
• Modern agriculture based on monocropping (better
  for large scale mechanization)
• Irrigation allowed for year-round cropping of the
  same crop (tropics)
• Creates ideal conditions for pests, natural
  controls are eliminated

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Mono-cropping creates ideal conditions for pests
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Heavy Reliance on Chemical Pesticides to Control
Insects and Weeds

• What are some of the impacts of doing it this
  way?
• Human health impacts (more on Wednesday)
• Loss of biodiversity in the fields pesticides
  kill both target and non-target species
• Loss of biodiversity higher up the food chain due
  to bio-magnification

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Heavy Reliance on Chemical Pesticides to Control
Insects and Weeds

• Why is this not sustainable?
• Pesticide resistance results in a pesticide
  treadmill
• Initial applications of a pesticide may kill
  99.9 of the target insect, but the 0.1 left
  behind will be resistant to the pesticide and
  their genes will be passed on to each new
  generation of pest
• Very short life spans for crop pests mean that in
  a short time pesticides will begin to lose their
  effectiveness (treadmill)

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Heavy Reliance on Chemical Pesticides to Control
Insects and Weeds

• What are the sustainable alternatives?
• Integrated pest management (Indonesia, the
  Philippines) promote conditions favorable for
  natural pest predators (e.g. ladybugs)
• Crop rotation altering the planting of crops
  from season-to-season disrupts insect lifecycles
• Strip cropping altering the spacing of crops
  prevents the rapid spread of pests throughout a
  field

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Natural predators help to keep crop pests under
control
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Crop diversity also helps to keep pests under
control
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Heavy Reliance on Chemical Pesticides to Control
Insects and Weeds

• What are the barriers to sustainable
  alternatives?
• Knowledge of IPM takes time to obtain
• The transition from chemical pesticides will
  probably result in lower yields for some time
• Chemical pesticides are cheap and work well in
  the short term
• Government subsidy programs promote mono-cropping
  on large acreages (more next week)

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Intensive soil manipulation and application of
chemical fertilizers.

• Why do we do it this way?
• Mono-cropping depletes nutrients from the soil
• Mechanization has led to soil compaction and soil
  erosion
• Lack of organic material being put back on the
  fields

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Intensive soil manipulation and application of
chemical fertilizers.

• What are the impacts of doing it this way?
• Over-application of fertilizers can contaminate
  groundwater supply
• Over-application of fertilizers and subsequent
  runoff of fertilizers from fields to bodies of
  water results in eutrophication (e.g. Gulf of
  Mexico dead zone)
• Over-reliance on chemical fertilizers and
  mechanization results in soil compaction and loss
  of organic matter in the soil this increases the
  rate of soil erosion from fields and impacts
  water quality

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Crops like corn are highly erosive
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Agricultural best management practices (BMPs)
include buffer strips between fields and bodies
of water
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Intensive soil manipulation and application of
chemical fertilizers.

• Why is this not sustainable?
• Fertilizer production is fossil fuel intensive,
  and chemical fertilizers are currently
  artificially under-priced (price ? cost)
• Long-term health problems (water contamination)
  from over-application of fertilizers
• Use of fertilizers to substitute for lost topsoil
  is only a temporary solution

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Intensive soil manipulation and application of
chemical fertilizers.

• What are sustainable alternatives?
• Strip cropping and crop rotation depends on crop
  DIVERSITY as a means of maintaining soil
  fertility and pest resistance
• Contour farming and terracing to help prevent
  soil erosion
• Use of soil building crops, nitrogen-fixing crops
  (e.g. legumes) or green manure
• Integrate livestock into cropping system in order
  to take advantage of nutrient and soil building
  benefits of manure

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Contour farming
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Pennsylvania farm practicing strip cropping
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Intensive soil manipulation and application of
chemical fertilizers.

• What are the barriers to sustainable
  alternatives?
• Difficult transition, knowledge of strip farming
  and ideal crop rotation takes time
• May result in initial declines in output per acre
• Fertilizers are cheap and easily available
• AGAIN, government subsidy programs reward
  mono-cropping and penalize inter-cropping, strip
  cropping and crop rotation

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Heavy reliance on external inputs of water and
energy

• Why do we do it this way?
• High-yielding varieties require large inputs of
  fertilizer (energy intensive), pesticides and
  water
• Modern agriculture is highly mechanized energy
  intensive
• What are the impacts of doing it this way?
• Depletion of fossil fuel
• Depletion of fossil water
• Salinization of soils

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Heavy reliance on external inputs of water and
energy

• Why is this not sustainable?
• From a NET ENERGY perspective, we are now using
  more energy to get less
• Limited fossil fuel and water supplies
• What are the sustainable alternatives?
• Adapt crops to growing conditions, favor more
  native varieties (as opposed to growing rice in
  the desert)
• Promote more local/regional agriculture
• Eat less meat!
• What are the barriers to sustainable
  alternatives?
• The usual suspects!