Agriculture and Food Supply

1) Soil Degradation & Sustainable Agriculture

2) Trends in Agriculture and Food Production

3) Solutions to Sustain a Global Food Supply

Maintain the Humus, Sustain Soil Fertility

• Partly decomposed organic matter.• Typically found in O & A horizons.• High capacity for holding water and nutrients.• More biologically active soil increases nutrient cycling.

Humus: To Be or Not to BeRoot systems add

humus too!Erosion processes

exacerbate topsoil loss.

Soil Degradation• Activities resulting in humus loss :

– Deforestation• Removal of forest litter source (trees)• Burning of slash and O-horizon humus

– Overgrazing• Surface litter completely removed.• Loss of productive root system organic inputs.

– Over-cultivation• Over-harvest (remove all crop biomass) • Tilling soil (accelerates soil organic matter oxidation)

• Factors that facilitate erosion:– Loss of living ground cover and humus– Susceptibility to wind and water forces

Extreme Soil Degradation:“Desert Pavement”

Causes of Soil Degradation

40% of global agricultural lands

Soil degradation is made worse by poor agricultural practices on already low fertility soils.

Golden Rules of Sustainable Agriculture

• Organic mulch for nutrients

• Maximize biomass production

• Maximize biodiversity of crop plants

• Cover the soil (cover crops; agroforestry)

• Minimal or zero tillage

• Protect from natural erosion forces– Wind (shelterbelts)– Water runoff (contour farming)

shelterbelts

contour farming & strip crops

Historical Trends in Agriculture and Food Supply

• Subsistence Farming:– Objective is family food security and some profit.– Pre-Industrial Revolution in developed countries.– Largely uses sustainable agricultural practices.– Human and animal labor intensive – low tech.– Deficit met by natural harvest (e.g. wild game).– Still dominant in developing countries.

• Population growth dominant in developing world.• Resort to non-sustainable practices that promote

environmental degradation (esp. soil loss).

Subsistence Farming Today: Answer More, Less, or the Same

as in the Past?• Labor intensive• Technologically

based• Use of marginally

productive lands• Clearing of tropical

rainforests• Over-cultivation• Over-grazing

Modern Industrialized Agriculture

• Bringing additional land into cultivation

• Increasing use of inorganic fertilizers

• Increasing use of herbicides and pesticides

• Increasing use of irrigation

• Substituting old varieties with genetic hybrids

• Fewer kinds of crops (reduced biodiversity)

• Less recycling of animal wastes

• More grain used for animal meat production

U.S. Corn Yields

The Green Revolution (1943)• Hybrid Mexican Wheat

heat resistant and high grain production.

• Temporarily closed the gap between food production and need in some developing countries.

• Heavy reliance on fossil fuels, herbicides, irrigation, fertilizers, and pesticides.

• Negative impact on small farmers and culturally specific crops.

Status of the Global Food Supply: Per Capita Food and Grain Production

No global shortage on average today.

But what about in 20 years? Can we increase by 40%?

Why is there still hunger today?

The Food Trade versus Food Aid• Profit over need in a global market economy.• North America is the major exporter of food.• Asia, Africa, and Latin America have become

the major food importers in the past 45 years.

• 20% are still hungry!• Food aid needed for famine.• Broader us of food aid today.

Food Aid: True or False

• Alleviates chronic hunger

• Helps local agriculture

• Disrupts local economy

• Contributes to ecological deterioration

Give a man a fish; you have fed him for today.Teach a man to fish; and you have fed him for a lifetime." --Old Chinese Saying

Solutions to Sustain a Global Food Supply

• Why not simply cultivate more land?

• Eat lower on the food chain & convert animal crops (feed grain) to human crops.

• Convert cash crops to food crops

• Consume less per capita & fewer pets

• Increase crop yields:– Restoration of soil fertility– The promise of genetically engineered foods

Promises of this Biotechniology

• Engender resistance to disease and pests

• Engender resistance to herbicides

• Increase tolerance range:– Drought– Salt

• Increase nutritional value

• Incorporate vaccines to human disease

What’s the advantage of each?

Problems with this Biotechnology

• Environmental problems:– Promote pesticide resistance in pests– Unwanted spread of toxins– Unwanted spread of traits

• Food Safety– Allergic reaction of transgenic proteins

• Access to the new technology– Large agro-industry ownership & profit motive– Illegal to propagate expensive patented seed