Transcript 1. ag and human health (good)

Food
• The major limiting factor to human
population growth
• Depends on environment and sociopolitical issues
• Right now distribution is the main problem
• If the human population continues to
grow, quantity will be the problem
Earth as an Apple
http://www.farmland.org/Flash/appleEarth.html
Where does our food come
from?
• Land crops and livestock!
– Only 14 species of plants
• Cash crops
• Subsistence crops
• Top food crops:
– Wheat, rice, maize, potatoes
How much food do people
need?
• 2600 calories/day
• If they don’t get this:
•
undernourishment
If they don’t get
specific nutrients:
malnourishment
– Marasmus,
kwashiorkor, chronic
hunger
• On the flip side of the
coin: obesity
Nutrition
•Undernourishment =
•too few calories
•(especially developing
world)
•Overnutrition =
•too many calories
•(especially developed
world)
•Malnutrition = lack of
nutritional requirements
Figure 9.2
Percentage of population affected by
undernutrition by country, according to
United Nations statistics
Global food security
•The world still has 800 million hungry people,
largely due to inadequate distribution.
•Global food security is a goal of scientists
and policymakers worldwide.
HOW TO FEED THE WORLD
• http://www.youtube.c
om/watch?v=QloMOO
G-bbE
The best ways
• “Give a man a fish
•
and you feed him for
a day. Teach a man
to fish and you feed
him for a lifetime.” –
Lao Tzu
Create systems where
food is grown and
distributed locally
Agriculture
Grain production
(millions of tons)
2,000
1,500
1,000
500
0
1950
1960
1970
1980
1990
Year
Total World Grain Production
2000
2010
Per capita grain production
(kilograms per person)
400
350
300
250
200
150
1950
1960
1970
1980
1990
Year
World Grain Production per Capita
2000
2010
Developed countries
3,500
3,300
3,100
2,900
World
2,700
Developing
countries
2,500
2,300
Year
2030
2010
2000
1990
1980
1970
2,100
1960
Calories per day per person
3,700
Natural Capital
Figure 14-3 Croplands
Page
Ecological276
Croplands
Services
Ecological Services
•Help maintain water flow and
• Help
maintain water
soil infiltration
Economic
Services
Economic Services
•Food crops
• Food crops
flow and soil infiltration
protection
• •Provide
Provide partial
partialerosion
erosion
protection
•Can build soil organic matter
• Can build soil organic
matter
•Store atmospheric carbon
• Store atmospheric
carbon
•Provide wildlife habitat for some
species
• Provide wildlife habitat
for some species
• Fiber crops
•Fiber crops
• Crop genetic
resources
•Crop genetic
• Jobsresources
•Jobs
Biodiversity Loss
Loss and degradation of habitat from
clearing grasslands and forests and
draining wetland
Fish kills from pesticide runoff
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
Waterlogging
Desertification
Air Pollution
Greenhouse gas emissions from fossil
Fuel issue
Other air pollutants from fossil fuel use
Pollution from pesticide sprays
Water
Water waste
Aquifer depletion
Surface and groundwater
pollution from pesticides
and fertilizers
Increased runoff and
Overfertilization of lakes
flooding from land cleared and slow-moving rivers
to grow crops
from runoff of nitrates
and phosphates from
Sediment pollution from
fertilizers, livestock
erosion
wastes, and food
processing wastes
Fish kills from pesticide
runoff
4%
2%
6%
5%
Crops
Livestock
Food processing
Food distribution and preparation
Food production
17% of total
commercial
energy use
Producing and eating meat
• Land use issues
– More land needed
• More land needed for grazing than grain
production
• Acre of grain for human consumption feeds more
than an acre used for grazing
• Land needed to grow forage AND raise animals:
Housing, food storage and waste disposal
Producing and eating meat
• Energy issues
– Eating at a lower trophic level
• More solar energy available to humans, less lost through
trophic transfer
– Storage of grain less energetically expensive than
processing and storing meat
• Transport, slaughter and refrigeration
– Energy costs associated with meat production
• Producing grain for livestock
– Fertilizers, irrigation, pesticides, farm machinery
• Animal waste management
– Pumping, treatment, transport, disposal
• Animal care and round up of free range livestock
Eating less meat: Pro and Con
• Advantages
– Reduced risk of disease
• Cholesterol
– Clogged arteries
– Hypertension
– Heart disease
– Reduced chemical exposure
•
•
•
•
Hormones
Steroids
Antibiotics
Pesticides (Biomag!)
– Reduced exposure to disease
• Mad Cow
• Salmonella/ E. coli
• Parasites
• Disadvantages
– Meat an excellent source of
protein
• Essential amino acids
– Rice and Beans!
• Difficult to get enough protein
without meat
– Nutritional deficiencies
•
•
•
•
•
Kwashikor: Protein
Blindness: Vit. A
Pollegra: Vit. B
Anemia: Iron
Inadequate essential fats
balance
How do we address world
hunger?
• Policy and behavioral
•
•
•
•
changes
Eat lower on the food
chain?
Modify food
distribution
Improve
infrastructure
Economic policies
– End subsidies
To feed the world….
• Conservation of matter
– Available resources limit agricultural production
– Nutrients used by plants
• Nitrates: Protein and DNA
• Phosphates: DNA, RNA, ATP
– Soil degraded as nutrients removed by harvest
• Conservation of Energy
– Trophic level energy loss
• Vegetarian vs Carnivorous diets
• Green revolution
–
–
–
–
Increase yield per acre
Monoculture
Intensive tillage = soil erosion
Requires
• Energy: Emissions and oil
• Fertilizers and pesticides: Toxic pollution, soil salinization
• Irrigation: Water rights and usage