Food

• The major limiting factor to human population

growth

• Depends on environment and socio-political

issues

• Right now distribution is the main problem

• If the human population continues to grow,

quantity will be the problem

9/29/2013

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Unit 3 1

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

Earth as an Apple

http://www.farmland.org/Flash/appleEarth.html

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Unit 3 2

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

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Unit 3 3

Nutrition •Undernourishment =

•too few calories

•(especially developing

world)

•Overnutrition =

•too many calories

•(especially developed

world)

•Malnutrition = lack of

nutritional requirements

•(causes numerous diseases,

esp. in developing world)

Figure 9.2 9/29/2013

Guru IBESS

Unit 3 4

Percentage of population affected by

undernutrition by country, according to

United Nations statistics

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Unit 3 5

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.

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Unit 3 6

HOW TO FEED THE WORLD

• http://www.youtube.co

m/watch?v=QloMOOG-

bbE

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Unit 3 7

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

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Unit 3 8

Agriculture

9/29/2013

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Unit 3 9

2,000

1,500

1,000

500

0

Gra

in p

rod

ucti

on

(millio

ns o

f to

ns)

1950 1960 1970 1980 1990 2000 2010

Total World Grain Production

Year

9/29/2013

Guru IBESS

Unit 3 10

400

350

300

250

150

Per

cap

ita g

rain

pro

du

cti

on

(kil

og

ram

s p

er

pers

on

)

1950 1960 1970 1980 1990 2000 2010

World Grain Production per Capita

200

Year

9/29/2013

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Unit 3 11

Calo

ries p

er

day p

er

pers

on

3,700

3,500

3,300

3,100

2,900

2,700

2,500

2,300

2,100

19

60

19

70

19

80

19

90

20

00

20

10

20

30

Year

Developed countries

World

Developing

countries

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Unit 3 12

Figure 14-3 Page 276

Croplands

• Help maintain water

flow and soil infiltration

• Provide partial erosion

protection

• Can build soil organic

matter

• Store atmospheric

carbon

• Provide wildlife habitat

for some species

Ecological Services Economic Services

• Food crops

• Fiber crops

• Crop genetic

resources

• Jobs

Natural Capital

Croplands

Ecological

Services

Economic

Services

•Help maintain water flow and

soil infiltration

•Provide partial erosion protection

•Can build soil organic matter

•Store atmospheric carbon

•Provide wildlife habitat for some

species

•Food crops

•Fiber crops

•Crop genetic

resources

•Jobs

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Unit 3 13

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

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Unit 3 14

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

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 and fertilizers Overfertilization of lakes and slow-moving rivers from runoff of nitrates and phosphates from fertilizers, livestock wastes, and food processing wastes

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Unit 3 15

4% 2% 6% 5%

17% of total commercial energy use

Crops Livestock Food processing Food distribution and preparation

Food production

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Unit 3 16

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

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Unit 3 17

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 9/29/2013

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Unit 3 18

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

9/29/2013

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Unit 3 19

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

9/29/2013

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Unit 3 20

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

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Unit 3 21