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