1. Issues and Impacts of Agriculture
Food Resources
Issues and Impacts of Agriculture

2. Main Topics Methods of producing food Increasing food production
Environmental effects of food production
Issues of sustainability

3. Sources of food worldwide
Of 30,000 edible plants, only 15 species.
supply 90% of our food
Primary plants: wheat, corn, and rice
Provide > ½ calories people consume
Primary animals: cattle, pigs, and chicken
2ndary: Eggs, milk & cheese

4. Major Types of Agriculture
Traditional subsistence
Shifting cultivation
Nomadic herding
Traditional intensive
Plantation
Industrialized

5. Industrialized agriculture Intensive traditional agriculture
Land
Industrialized agriculture
in developed countries
Labor
Capital
Fossil fuel
energy
Land
Intensive traditional agriculture
in developing countries
Labor
Capital
Fossil fuel energy
Fig. 12.3a, p. 264

6. Shifting cultivation in tropical
forests
in developing countries
Land
Labor
Capital
Nomadic herding in
developing countries
Land
Labor
Capital
Fig. 12.3b, p. 264

7. World Food Production Plantation agriculture
Industrialized agriculture
Shifting cultivation
Plantation agriculture
Nomadic herding
Intensive traditional agriculture
No agriculture
Fig. 12.2, p. 263

8. Total World Grain Production
2,000
1,500
1,000
500
Grain production
(millions of tons)
1950
1960
1970
1980
1990
2000
2010
Fig. 12.8a, p. 268

9. Per Capita World Grain Production
400
350
Per capita grain production
(kilograms per person)
300
250
200
150
1950
1960
1970
1980
1990
2000
2010
Fig. 12.8b, p. 268

10. Green Revolutions First green revolution (developed countries)
Second green revolution
(developing countries)
Major International agricultural
research centers and seed banks
Fig. 12.4, p. 265

11. Producing Food by Green-Revolution Techniques
High-input monoculture
Selectively bred or genetically-engineered crops
High inputs of fertilizer
Extensive use of pesticides
High inputs of water
Increased intensity and frequency of cropping

12. To increase rice yields: More, bigger grain per stalk (heavier head)
More stalks per acre
(higher density)
More plantings per year
Heavier heads required:
more fertilizer, water, hybrids with shorter stalks (to prevent lodging)
Higher density plantings required:
more fertilizer, constant water, hybrids with smaller root system
More plantings per year required:
more fertilizer, year round water, pesticides
More fertilizer, water, pesticides & hybrid seed required:
more energy, esp. from fossil fuels
more cash, especially US dollars

13. Results of Green Revolution: Mixed
Higher yields per acre when inputs available
Lower yields when inputs unavailable
Increased dependence on cash economy
Increased dependence on fossil fuel
Increased imports of inputs
Income disparity??
Migration to cities??

14. Unintended consequences: Killer Bees
Mild-mannered, low honey producing Italian bee X
Aggressive, high honey producing African bee?
Hope for a mild-mannered, high producing bee
Instead, got an aggressive, low producing bee
Worse yet – it escaped, and is interbreeding with other bees making them aggressive & low producing too!

15. Environmental Effects of Food Production
Biodiversity loss
Soil degradation
Air pollution
Water pollution
Human health

16. Biodiversity Loss Soil
Loss and degradation of habitat from
clearing grasslands and forests and
draining wetland
Invasive species out competing natives
Killing of wild predators to protect
livestock
Loss of genetic diversity from
replacing thousands of wild crop
strains with a few monoculture strains
Erosion
Loss of fertility
Salinization from irrigation
Desertification
Fig a, p. 271

17. Greenhouse gas emissions from fossil fuel use
Air & Climate
Water
Greenhouse gas emissions from fossil fuel use
Other air pollutants from fossil fuel use
Pesticide drift from spraying
Dust / airborne particulates
Weather alteration from large scale clearing
Aquifer depletion
Water diversions
Increased runoff and
flooding from land cleared
to grow crops
Sediment pollution from
erosion
Fish kills from pesticide
runoff
Surface and groundwater
pollution from pesticides, fertilizers & livestock
Overfertilization (eutrophication) of lakes
and slow-moving rivers
from runoff of nitrates and
phosphates from
fertilizers, livestock
wastes, and food
processing wastes
Fig b, p. 271

18. Nitrates in drinking water Pesticides residues in drinking water,
Human Health
Nitrates in drinking water
Pesticides residues in drinking water,
food, and air
Contamination of drinking and
swimming water with disease organisms from livestock wastes
Bacterial contamination of meat
Farm worker exposure & working conditions
Fig c, p. 271

19. Food Production since Green Rev
Rapid increases in total production
Prices decreasing
Shortages in developing countries
Approaching limits on meat production

20. Increasing World Crop Production
Crossbreeding and artificial selection
Genetically modified organisms (GMOs)
Continued Green Revolution techniques
Introducing new foods
Working more land

21. Alternative Solutions: Sustainable Agriculture
Low-input agriculture
Organic farming
See Fig p. 291
Non-meat alternatives
Research in sustainable techniques

22. In Summary:
Supplying food for the world’s growing population was and still is an issue.
Policy and research play a big role.
Efforts to increase production have focused on:
Improved varieties thru breeding and genetic engineering
Inputs, esp. chemicals, energy and water
Agriculture has multiple impacts on the environment and human health
Sustainable agricultural techniques are growing but far behind conventional