environment

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

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

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

8. 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

9. 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

10. 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
To increase rice yields:
More, bigger grain per stalk
(heavier head)
More stalks per acre
(higher density)
More plantings per year
More fertilizer, water, pesticides & hybrid seed required:
more energy, esp. from fossil fuels
more cash, especially US dollars

11. 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??

12. 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!

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

14. Fig. 12.10a, p. 271
Biodiversity Loss
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
Soil
Erosion
Loss of fertility
Salinization from irrigation
Desertification

15. Fig. 12.10b, p. 271
Air & Climate
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
Water
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

16. Fig. 12.10c, p. 271
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

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

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

19. Alternative Solutions:
Sustainable Agriculture
Low-input agriculture
Organic farming
Non-meat alternatives
Research in sustainable techniques
See Fig. 12-21 p. 291

20. Soil failure and the sheep boom
• Soils, crop yields already in decline
• Merino sheep introduced 1811 & breeding ↑ yields 143%
• Wool tariffs 1824
• Civil War 1860s (wool blankets!)
• 1.5 million sheep in VT in mid-1800s
• Hillsides denuded
• After Civil War, sheep industry failed in VT
• Farms abandoned

21. And Cows still with us.
1525 of VT’s 6800 farms are dairy
Served New England market
for milk, butter & cheese.
In 1960, 10,000 dairy
farms produced half the
milk that the current 1525
farms produce now!
Average herd size ↑↑
Production per cow ↑↑
Jersey cows bred in VT
helped make VT butter and
cheese famous!
Breeding & other ag research
remain import to VT’s economy
and environment.