Where does our food come
from?
• Croplands (mostly grain) – provide 77%
of the world’s food
• Rangelands (meat) supply 16%
• Oceanic fisheries (fish and shellfish) –
7%
How Is Food Produced?
• Sources of food
• Primary plants: Wheat, corn, and rice
• Primary animals:
fish, beef, pork, and chicken
• 14 plant and 8 animal species provide
90% of the global food calories
Major Types of Agriculture
• Industrialized agriculture
• Large amounts of fossil fuel, water, fertilizer, and
pesticides to produce monoculture crops or livestock
animals
• Plantation
• Form of industrialized agriculture – single ownership
• Traditional subsistence agriculture
– Produce only enough for the family
• Traditional intensive agriculture
– Increase outputs for profit
Industrialized Agricultural
Wastes and Land Pollution
• Animal Confinement
– Waste runoff
• Overgrazing
– Increases soil erosion
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Sedimentation
Nutrient application
Irrigation
Pesticides
Waste runoff increases nutrients
and pathogens in streams
Overgrazing typically strips the
land of any natural protection and
leaves the soil very susceptible to
erosion
Runoff carries sediments, nutrients and
pesticides into streams that damages
fish habitat
Agriculture alters native habitats
and reduces native biodiversity
Major Types of Agriculture
• Plantation - Form of agriculture that involves
concentrated ownership of land with the
means of production in the hands of one
family or corporation, the use of hired labor,
and mono-crop production for sale.
• Cash crops mostly for sale in developed
countries
• Bananas, coffee, soybeans
Traditional
Industrialized
Plantation
World Food Production
ustrialized
Traditional
Producing Food by GreenRevolution Techniques
• Since 1950, increase in global food
production has come from increased
yields per unit area of crop land.
Producing Food by GreenRevolution Techniques
•
Green revolution involves three steps:
1. High-input monoculture using selectively
bred or genetically-engineered crops
2. High yields using high inputs of fertilizer,
extensive use of pesticides and high
inputs of water
3. Multiple cropping – increase the number
of crops grown per year on a plot of land.
Green Revolutions
First green revolution
Second green revolution
(developed countries)
(developing countries)
Major International agricultural
research centers and seed banks
Producing Food by Traditional Techniques
Interplanting – simultaneously grow several
crops on the same ground. Reduces chance of
losing year’s crop to pests, bad weather, etc.
Producing Food by Traditional
Techniques
• Types of Interplanting
– Polyvarietal cultivation – planting several varieties of
the same crop
– Intercropping – grow two or more different crops at
the same time (grain+nitrogen fixing plant)
– Agroforestry (alley cropping) – crops and trees are
grown together
– Polyculture – many different types of plants that
mature at different times are grown together
Causes of Soil Erosion
• Wind
• Water
• People – farming, logging,
construction (or any activities that
weaken root strength)
Soil erosion in a wheat field
Global Soil Erosion
Areas of serious concern
Areas of some concern
Stable or nonvegetative areas
Soil Degradation on Irrigated Land
• Salinization
• Waterlogging
Evaporation
Evaporation
Transpiration
Waterlogging
Less permeable
clay layer
Reducing and Cleaning Up
Salinization
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Reduce irrigation
Switch to salt-tolerant crops
Flush soils
Not growing crops for 2-5 years
Install underground drainage
Saltwater and drainage is a continual problem for
lowland agriculture near Puget Sound.
Tidegate – lets water out, but not back in.
Solutions: Soil Conservation
Soil Restoration
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Organic fertilizer
Animal manure
Green manure – fresh cut vegetation
Compost
Crop rotation – legume crops add nitrogen
to soil
• Commercial inorganic fertilizer
Catching and Raising More Fish
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Fisheries
Fishing methods
Overfishing
Commercial extinction
Aquiculture
Fish farming and ranching
Pesticides: Types
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Chemicals that kill undesirable organisms
Insecticides - insects
Herbicides - plants
Fungicides - fungus
Rodenticides - rodents
First Generation Pesticides
• Primarily natural substances
• Sulfur, lead, arsenic, mercury
• Plant extracts: nicotine, pyrethrum
Second Generation Pesticides
• Primarily synthetic organic compounds
• Broad-spectrum agents – toxic to many
species
• Narrow-spectrum agents – toxic to few
species
• Persistence in the environment
The Case for Pesticides
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Save human lives – spread of disease
Increase food supplies and lower costs
Work better and faster than alternatives
Health risks may be insignificant
compared to benefits
• Newer pesticides are becoming safer
• New pesticides are used at lower rates
Characteristics of an Ideal Pesticide
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Affects only target pests
Harms no other species
No genetic resistance
Breaks down quickly in the environment
Be more cost-effective than doing nothing
The Case Against Pesticides
• Genetic resistance
• The pesticide treadmill – pay more for less
effect
• Can kill non-target and natural control
species
• Can cause an increase in other pest species
• Pesticides do not stay put
• Can harm wildlife
• Potential human health threats
Bioaccumulation and Biomagnification
• Persistent (nonbiodegradable)
toxins build up in
an animal over
time =
bioaccumulation
• Become more
concentrated at
higher trophic
levels =
biomagnification
Integrated Pest Management
• Ecological system approach
• Reduce pest populations to economic
threshold
• Field monitoring of pest populations
• Use of biological agents – natural
predators, parasites, disease
• Chemical pesticides are last resort
Why is Integrated Pest Management
not More Widely Used?
• Requires expert knowledge
• Slower than conventional pesticides
• Initial costs may be high
• Hindered by pesticide industry
Solutions: Sustainable Agriculture
• Low-input agriculture
• Organic farming
• Profitable
• Increasing funding for research in
sustainable techniques