Food Resources
Issues and Impacts of Agriculture
ENVS 1 Oct. 14, 2002
See Miller Chapter 12
Main Topics
 Methods of producing food
 Increasing food production
 Environmental effects of food production
 Issues of sustainability
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
Major Types of Agriculture
Traditional subsistence
Shifting cultivation
Nomadic herding
Traditional intensive
Plantation
Industrialized
Land
Labor
Capital
Industrialized
agriculture
in developed
countries
Fossil fuel
energy
Land
Labor
Capital
Fossil fuel energy
Intensive
traditional
agriculture
in developing
countries
Fig. 12.3a, p. 264
Land
Labor
Capital
Land
Labor
Shifting cultivation
in tropical
forests
in developing
countries
Nomadic
herding in
developing
countries
Capital
Fig. 12.3b, p. 264
World Food Production
Industrialized agriculture
Plantation agriculture
Shifting cultivation
Nomadic herding
Intensive traditional agriculture
No agriculture
Fig. 12.2, p. 263
Total World Grain Production
Grain production
(millions of tons)
2,000
1,500
1,000
500
0
1950
1960
1970
1980
1990
2000
2010
Fig. 12.8a, p. 268
Per capita grain production
(kilograms per person)
Per Capita World Grain Production
400
350
300
250
200
150
1950
1960
1970
1980
1990
2000
2010
Fig. 12.8b, p. 268
Green Revolutions
First green revolution
Second green revolution
(developed countries)
(developing countries)
Major International agricultural
research centers and seed banks
Fig. 12.4, p. 265
Producing Food by GreenRevolution 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
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
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??
Unintended consequences: Killer Bees
Mild-mannered, low honey producing Italian bee
X
Aggressive, high honey producing African bee?
Hope for a mildmannered, 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!
Environmental Effects of Food
Production
Biodiversity loss
Soil degradation
Air pollution
Water pollution
Human health
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
Soil
Erosion
Loss of fertility
Salinization from irrigation
Desertification
Loss of genetic diversity from
replacing thousands of wild crop
strains with a few monoculture strains
Fig. 12.10a, 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
Fig. 12.10b, 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
Fig. 12.10c, p. 271
Food Production since Green Rev
Rapid increases in total production
Prices decreasing
Shortages in developing countries
Approaching limits on meat production
Increasing World Crop Production
 Crossbreeding and artificial selection
 Genetically modified organisms (GMOs)
 Continued Green Revolution techniques
 Introducing new foods
 Working more land
Alternative Solutions:
Sustainable Agriculture
Low-input agriculture
Organic farming
See Fig. 12-21 p. 291
Non-meat alternatives
Research in sustainable techniques
Vermont:
A case of agricultural innovation and
environmental degradation
Developing & disseminating new breeds:
• Merino sheep
• Jersey cow
• Morgan horse
• Green Mountain potato
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
What’s was next for Vermont?
5 cows earn $357.50 per year, while 40 sheep net only
$40 per year
-- Vermont Board of Agriculture, 1868
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.
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