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AGEC/FNR 406 LECTURE 38 - PowerPoint PPT Presentation

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AGEC/FNR 406 LECTURE 38. Rice Paddy. World Food Production. Major links between food production and the environment: 1. Food production relies on good quality land and adequate supplies of water;

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Rice Paddy


World Food Production

Major links between food production and the environment:

1. Food production relies on good quality land and adequate supplies of water;

2. Historically, most land clearing has been for agriculture;

3. Wide range of agricultural impacts on the environment.


Why are people inthe developed world well fed…

One major factor: developed world has 45% of arable land but only 25% of population

... while those in developing countries are less well fed?


Food vs. population...

Aggregate food production has grown dramatically in past 100 years

Two main sources of increases in food production:1. Area expansion

2. Technical progress

Indicator of growth in food production: long-term trend in food prices has been downward, but concerns about a slowdown in food production have been raised.


Per capita food production

Calculated as: total production/population

Growing, but not as rapidly as total production Annual growth rates: 1950s: 1.4% 1960s: 0.8% 1970s: 0.4% 1980s: 0.4% … and holding steady


Cropland per person

Calculated as: area in production/population

world average = 0.75 acres/personN. America average = 2.17 acres/personDeclining everywhere!

Some examples (% change 1961-86):N. Africa: down 47% (0.77 acres) China: down 44% (0.22 acres) SSA: down 39% (0.82 acres) S. Asia: down 39% (0.49 acres)


Figure: World Agricultural Output, 1961-90

Key point: aggregate production continues to climb, but per capita production is leveling off.


Food per personWorld average area per person = 0.30 hectares“Typical” grain yield = 3000 kg/ha

This translates into 2.5 kg/person/dayAverage calorie content = approx. 2500KCal/kgThis translates into 6250 Kcal/person/dayMore than enough! So what’s the problem?

Key point: aggregate production continues to climb, but per capita production is leveling off.


Food production per person

Increasing everywhere except sub-Saharan Africa

Fastest growth: developed countries


1. Slow population growth

2. Crop improvements


Sources of increases in food production

1. New land (forests, deserts)

2. Reduction in fallow (currently 1/3 of arable)

3. Multiple cropping (rainfall limiting factor)

4. Intensification (new varieties, irrigation)

green revolution
Green Revolution

Development of new varieties (originally of wheat in Mexico and rice in the Philippines) during the 1950s and 60s.High yielding varieties (HYVs) (also known as modern varieties (MVs)) were more responsive to inorganic fertilizer and irrigation, and faster maturing. Bred with pest and disease resistance.

impacts on agriculture
Impacts on agriculture

1. MVs profitable, replaced TVs

2. Irrigation expanded

3. Use of chemicals increased

4. Diversity of genetic material reduced b/c MVs related via common ancestors (see Table from Fowler and Mooney)

impacts on food production
Impacts on food production

1. In areas with MVs, food production doubled or tripled in 20-30 years, far surpassing increases in population.

2. Less yield variability

3. Lower food prices

impacts on poverty and nutrition
Impacts on poverty and nutrition

1. More food: unambiguous impact

2. Lower food prices

3. Large farms bias?

4. More food necessary but not sufficient to eradicate poverty and malnutrition

impacts on environment
Impacts on environment
  • 1. Irrigation leads to salinization
  • 2. Fertilizer use increases nutrient loads
  • 3. Pesticides may impair ecosystem health
  • Biotech may have uncertain impact
critiques of green revolution
Critiques of Green Revolution

1. “Social” critiquea. the green revolution didn’t fix problems associated with access by the poor b. technology destroys social fabric

  • “Scientific” critiquea. the green revolution escalated uses of technology, especially environmentally damaging technologies b. GR reduced genetic diversity