Agriculture

1
Agriculture

• Agriculture encompasses both cultivation of crops
  and raising of livestock.
• Origin of agriculture is uncertain, but thought
  to be about 10,000 ybp.

2
Origins of Domestication
3
Natural Limits on Agriculture

• Insolation.
• Water availability.
• Soil fertility
• Competition.
• Gene pool.

4
Challenging the Constraints

• Irrigation.
• Fertilizers.
• Pesticides.
• Genetic engineering.

5
Threats to Irrigation

• Groundwater supplies can be depleted.
• Soil can be degraded.
• Water-borne diseases can proliferate.
• Infrastructure can be destroyed.

6
Groundwater Extraction

• Increased facility to extract groundwater.
• Expanded water demand.
• Increased extraction coincides with reduction in
  groundwater recharge.

7
OgallalaAquifer
http//www.rra.dst.tx.us/gw/Ogallala_1.cfm
8
Contributing Factors for Excessive Exploitation

• ? number of wells.
• ? area of irrigated farmland.
• Development of centre-pivot irrigation systems.

9
Contributing Factors for Diminished Exploitation

• Increased energy costs for pumping.
• Improved irrigation technology.
• Rural out migration.

10
Mesopotamia 2500 BCE
http//www.fsmitha.com/h1/map01mes.htm
11
Waterlogged Field
http//www.greenfacts.org/glossary/wxyz/waterloggi
ng.htm
12
Gezira Irrigation Canals
http//www.greatmirror.com/index.cfm?chapterid386
countryid381
13
Primary Fertilizers

• Compound fertilizers (nitrogen, phosphorus, and
  potassium).
• Calcium-bearing material (limestone ).

14
Fertilizers as Pollutants

• Excess nitrate and phosphate carried to rivers,
  lakes, groundwater, and coastal waters ?
  eutrophication.
• Excess nitrate ? nitrous oxide, a greenhouse gas.
• Excess nitrate ? nitric oxide, an ozone depleting
  substance.
• Excess nitrate ? ammonia ? acid deposition when
  oxidised.
• Dissolved nitrate is a health hazard.

15
Pesticide Impact

• Resistance in pest populations.
• Demise of non-target species.
• Contamination of water, air, soil.
• Bioaccumulation biomagnification.
• Adverse health of agricultural workers.

16
DDT

• First synthesized in 1874.
• Initially thought an ideal pesticide.
• Detrimental consequences eventually identified
  (migration, bioaccumulation biomagnification,
  impact on non-target species,).
• Banned with some exceptions.

17
Bhopal 3 December 1984

• Union Carbide (now Dow) pesticide plant in Bhopal
  opened in 1969.
• Phosgene ? methyl isocyanate (MIC) ? carbamate
  pesticides.
• Plant had history of accidents.
• Decisions taken by senior officials at Union
  Carbide increased danger.
• Thermal runaway explosive reaction released toxic
  gases ? death and disease.

18
Impacts

• Immediate
• Gases burned tissues and entered bloodstream.
• 40 pregnancies ? miscarriage.
• Long-term
• Health issues.
• Psychological disorders.
• Sociocultural repercussions.

19
Compensation

• In 1989 Union Carbide agreed to pay compensation.
• Average 580 for injuries and 1300 for death.
• Problems exist.

20
Soil Erosion

• Removes nutrient-rich surface soil.
• Agricultural systems particularly vulnerable to
  erosion.
• Certain agricultural practices ? vulnerability to
  erosion.
• E.g. fallowing without cover crop
• E.g. conventional tillage.

21
World Production (UNFAO)
22
Factory Farmed Pigs
Worldwatch Institute, 2003. Vital Signs 2003.
W.W. Norton Company, New York.
23
Factory Farming by Sector as a Percentage of
Global Production
Worldwatch Institute, 2004. State of the World.
Norton, New York.
24
Genetic Engineering

• Genetic engineering is a set of techniques for
  isolating, modifying, multiplying, and
  recombining genes from different organisms.
• Capra, 2002

25
DNA Discoveries Techniques

• 1950s double helix structure of DNA discovered.
• 1970s techniques for DNA sequencing and gene
  splicing developed.

26
Arguments for Genetic Engineering in Agriculture

• Potential for increasing yield.
• Potential for increasing tolerance of
  environmental stresses.

27
Concerns about GM Food

• New virulent strains of viruses.
• Introduction of altered genes into traditional
  cultivars and wild species.
• Resistant pest populations.
• Reduced genetic diversity.
• Increased use of herbicides.
• Dependence on transnational companies.
• Contamination of organic farms.
• Ethics.

28
Alternatives to Irrigation

• More efficient transport and application
  techniques.
• Low water demanding crops.
• Small scale projects.
• E.g. tassas.
• Importation of food.

29
Alternatives to Synthetic Fertilisers

• Nitrogen-fixing leguminous plants.
• Nutrient cycling decomposer microbes.
• Fallow periods and rotation.

30
Alternatives to Pesticides

• Biological control.
• Mechanical control.
• Intercropping.
• Refuge strips.
• Application of pesticide above pest population
  threshold.
• Acceptance of trade off.

31
Protection against Soil Erosion

• Conservation tillage (tie-in benefits).
• Terracing.
• Contour ploughing.
• Mulching.
• Windbreaks.

32
Terracesin Peru
http//www.andrys.com/peru4.html
33
Grassroots Projects

• Cost less than large scale schemes.
• Build on traditional and local knowledge of the
  environment.
• Accessible to the poor.
• E.g. World Neighbours.
• E.g. Campesino a Campesino

34
Concentrated Control in Canada

• 3 companies control gt 70 of fertilizer sales.
• 2 companies control gt 70 of beef packing.
• 4 companies mill 80 of the wheat.
• 5 companies dominate food retailing.

35
Legislation

• Tax on pesticides.
• Tax on factory farms.
• Shift in government subsidies from commodities to
  ecological goals.
• Support for farmers during the transition from
  conventional to sustainable production.

36
Ethical Eating

• Fair trade.
• Land equity.
• Buying locally grown food.
• Animal welfare.

37
Benefits of Locally Grown Food

• Farmers obtain ? proportion of the profit.
• ? environmental and monetary costs of transport.
• ? food quality.
• ? risk of food contamination.

38
Hunger

• Commitment to reduce world hunger by 50 voiced
  in 1996, 2001, and 2002.
• In Africa food production lt population growth.
• Worldwide most arable is being cultivated.
• Possible to ? yield on marginal land and use
  non-traditional space.