Hungry to learn?
• Please read the board
and get out something to
write with!

“The way we eat has
changed more in the past
50 years than in the past
10,000 years.”
Big changes
• Uniformity of
product
• Control by very few
companies
• Industrial food
processes
• Monoculture
• Processing
It produces a
lot of food, but
is this
sustainable?
 (Something that can go
on and on because it
doesn’t use up resources
faster than they are
created.)
Remember the lesson of the Inca!
Monoculture
Monoculture
Polyculture
Polyculture
Polyculture
What are the tradeoffs of monoculture?




Benefits:
Easy to manage
Provides uniformity
Can be grown by few
people as long as they
have large machines
 Lack of diversity =
potential loss of crop to
disease/pest
 Need for pesticides
 Need for inorganic
fertilizer because crop
takes particular nutrient
from soil
 Loss of biodiversity from
field edges/cover crops
Pests and diseases generally are
plant-specific.
• Examples –
• Boll weevil attacks
cotton plants
• Rust fungus attacks
corn
• Yellow rust fungus
attacks wheat
• Colorado potato beetle
only attacks potatoes
Diversity protects harvests from pests
and diseases because they run out of
food.
Monocultures are like a banquet!
Pesticides can move through the environment
• Monocultures are often
crop dusted by planes.
• If it rains soon after
application, pesticide can
runoff into local stream.
What happens in a farming community’s
watershed?
• Where would the greatest
concentrations of
pesticide be?
Biomagnification: the accumulation of toxins as
they move up the food chain.
Genetic Resistance
• Individual pests can
tolerate different
amounts of
pesticide. Some
individuals are
stronger than
others and they can
survive.
The pesticide treadmill
• Pests develop resistance
to pesticide
• Farmer must use
Increased dosage,
application schedule,
increased toxicity
• It’s like a treadmill
because once a farmer
starts, it’s hard to stop
using pesticides.
The Tradeoffs!
• Advantages
• Disadvantages
Why are monocultures unsustainable?