Transcript Environmental Science Power Point Lecture

Food and
Agriculture
History and Types of
Agriculture
Demand-based agriculture - production determined by
economic demand and limited by classical economic
supply and demand theory. This approach became
common during the industrial revolution.
Resource-based agriculture - production determined
by resource availability; economic demand usually
exceeds production. This approach was the original
type of farming 10,000 years ago. Modern
approaches are very high tech and somewhat more
expensive.
Plant Food Sources
250,000 plant species 
3000 tried as crops 
300 grown for food 
100 species used on large scale for food 
15 to 20 species provide vast majority (90%) of
man’s food needs
• It takes about 16 pounds of grain to produce one
pound of edible meat
• Largest crop volumes provided by: wheat, rice,
corn, potatoes, barley
– Wheat and rice supply ~60% of human caloric
intake
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Other Plant Food Sources
1.
2.
3.
4.
5.
6.
7.
8.
9.
Potatoes
Barley
Sweet Potato
Cassava
(source of
tapioca)
Grape
Soybean
Oats
Sorghum
Sugarcane
10. Millet
11. Banana
12. Tomato
13. Sugar Beet
14. Rye
15. Orange
16. Coconut
17. Cottonseed
18. Apple
19. Yam
20. Peanut
21. Watermelon
22. Cabbage
23. Onion
24. Bean
25. Pea
26. Sunflower
Seed
27. Mango
Types of Crops
• Cash crops vs. subsistence crops
• cash crops may provide non-food
products (latex)
• provide products which do not
make up our primary nutrition
(tea, coffee)
Agroecosystems
• Ecosystem created by agricultural
practices
–characterized by low
• Genetic diversity
• Species diversity
• Habitat diversity
Agroecosystems
Agroecosystems differ from natural ecosystems in five
major ways:
1. Farming attempts to stop ecological succession
2. Species diversity is low
a.farmers usually practice monoculture
b.monoculture tends to  soil fertility
3. Farmers plant species (crops) in an orderly fashion this can make pest control more difficult
4. Food chains are far more simple in agroecosystems
5. Plowing is like no other natural disturbance
a.plowing can  erosion
b.cause more nutrient loss (which is replaced by
fertilizer)
World Food Supply and the Environment
• Our current food problem is the result of
our human population
• Food production depends upon
favorable environmental conditions
• Agriculture changes the environment such changes can be detrimental
• Food supply can be adversely affected
by social unrest that influence
agriculture
Grain Production
•
Grain production increased from 631 to 1780 million
metric tons from 1950 to 1990.
• Has leveled off since then
• Top five countries in order of producing the most
amount of grain are:
1. China
2. United States
3. India
4. Canada
5. Ukraine
Livestock
 domesticated livestock (sheep, pigs,
chickens, cattle) are an important food
source for humans
 ruminants (four-chambered stomachs)
contain bacteria that can convert plant
tissue to animal protein/fat  hence,
plant material originally unusable for man
is converted into food sources that can
be ingested by man
Wilkes, Angela. My first word board book. (1999) DK Publishing, NY.
Meat Sources
• About 90% of all meat and milk are consumed by
United States, Europe and Japan which constitute only
20% of world population
• About 90% of the grain grown in the United States is
used for animal feed
• 16 kg of grain 1 kg of meat
– By eating grain instead would get 20 times the
calories and 8 times the protein
Malnutrition and Famines
• One quarter of the human population is malnourished
– Sub-Saharan Africa (~225 million)
– East and Southeast Asia (~275 million)
– South Asia (~250 million)
– Parts of Latin America
Malnutrition/Famines
• Stem from not enough calories per day in addition to not
getting the necessary amounts of carbohydrates, proteins,
lipids (fats), minerals, and vitamins
• Generally diets are high in starches
• Famine conditions
– Major droughts
-- Political instability
– Population sizes
-- Land Seizures
– Massive immigration
-- Pestilence
– Floods
-- Distribution breakdown
– Wars
--Panic buying
– Chaos in economy
-- Hoarding
Limits on Food Production
 arable land
 precipitation
 temperature
 Climate change
Methods to Increase Food Supply
• Improved irrigation and utilization of water
– Drip irrigation
• Increasing arable land
– Difficult because of precipitation and
temperature
• Eating lower on the food chain
– Most rangeland is not arable and humans
cannot utilize grass/hay as food; therefore,
this argument is not considered valid
Methods to Increase Food Supply
• Food distribution modification
– Today distribution of food is a major
problem in Africa/Asia
– Best solution: teach locals how to best
utilize their land with appropriate
technology so they can attempt to support
themselves and not rely on others.
New vs. Old
Agriculture
Soil Resources
• What is Soil?
• Ways We Use and Abuse Soil
• Erosion
How much Land
is Arable?
Pests and
Pesticides
The problem with chemicals
• Groundwater contamination
• Effects of low concentrations?
• Bioaccumulation and Biomagnification
Pesticides Pro and Con
• Kill unwanted pests that carry
disease (rats, mosquitoes,
Tse-Tse flies)
• Increase food supplies
• More food means food is less
expensive
• Effective and fast-acting
• Newer pesticides are safer,
more specific
• Reduces labor costs on farms
• Food looks better
• Agriculture is more profitable
• Accumulate in food chain
• Pests develop resistance –
500 species so far
• Resistance creates pesticide
treadmill
• Estimates are $5-10 in
damage done for $1 spent on
pesticide
• Pesticide runoff
• Destroy bees - $200 million
• Threaten endangered species
• Affect egg shell of birds
• 5% actually reach pest
• ~20,000 human deaths/year
Types of Pesticides
• Biological – Ladybugs, parasitic wasps, etc.
• Carbamates effect nervous system of pests more water
soluble than chlorinated hydrocarbons
– Aldicarb, aminocarb, carbaryl (Sevin), carbofuran,
Mirex
• Chlorinated Hydrocarbons affect nervous system –
– Aldrin, Chlordane, DDT, dieldrin, lindane and
paradichlorobenzene
• Fumigants are used to sterilize soil and prevent grain
infestation
Types of Pesticides
• Inorganic – arsenic, copper, lead, mercury
– Highly toxic and bioaccumulation
• Organic or natural – derived from plants such as
tobacco and chrysanthemum
• Organophosphates – extremely toxic, low persistence
– Malathion, parthion, chlophyrifos, acepate,
propetamphos and trichlofon
Pesticide Protection Laws in
the U.S.
• Government regulation has banned a number of
harmful pesticides but some scientists call for
strengthening pesticide laws.
– The Environmental Protection Agency (EPA), the
Department of Agriculture (USDA), and the Food
and Drug Administration (FDA) regulate the sales
of pesticides under the Federal Insecticide,
Fungicide and Rodenticide Act (FIFRA).
– The EPA has only evaluated the health effects of
10% of the active ingredients of all pesticides.
What Can You Do?
Reducing Exposure to Pesticides
• Grow some of your food using organic methods.
• Buy organic food.
• Wash and scrub all fresh fruits, vegetables, and wild foods you pick.
• Eat less or no meat.
• Trim the fat from meat.
Fig. 13-30, p. 299
Integrated Pest Management
• Some practices for preventing pest damage may
include
– inspecting crops and monitoring crops for damage
– using mechanical trapping devices
– natural predators (e.g., insects that eat other insects)
– insect growth regulators
– mating disruption substances (pheromones)
– if necessary, chemical pesticides
Parts of IPM
• Polyculture instead of monoculture
• Intercropping – alternate rows of crops that have different
pests
• Planting pest-repellent crops
• Mulch to control weeds
• Natural insect predators – ladybugs, preying mantis, birds
• Rotating crops to disrupt insect cycles
• Using Pheromones to attract insects to traps
• Releasing sterilized insects
Solutions
Sustainable Organic Agriculture
More
High-yield
polyculture
Organic fertilizers
Biological pest
control
Integrated pest
management
Efficient
irrigation
Perennial crops
Crop rotation
Water-efficient
crops
Soil conservation
Subsidies for
sustainable farming
and fishing
Less
Soil erosion
Soil salinization
Aquifer depletion
Overgrazing
Overfishing
Loss of
biodiversity
Loss of prime
cropland
Food waste
Subsidies for
unsustainable
farming and
fishing
Population
growth
Poverty
Fig. 13-33, p. 302
Sustainable
Agriculture
• Results of 22 year
study comparing
organic and
conventional
farming.
Figure 13-34
Solutions
Organic Farming
Improves soil fertility
Reduces soil erosion
Retains more water in soil
during drought years
Uses about 30% less
energy per unit of yield
Lowers CO2 emissions
Reduces water pollution
from recycling livestock
wastes
Eliminates pollution
from pesticides
Increases biodiversity
above and below ground
Benefits wildlife such as
birds and bats
Fig. 13-34, p. 302
What Can You Do?
Sustainable Organic Agriculture
• Waste less food
• Eat less or no meat
• Feed pets balanced grain foods instead of meat
• Use organic farming to grow some of your food
• Buy organic food
• Eat locally grown food
• Compost food wastes
Fig. 13-35, p. 303