lesson 9: agriculture and environment big question: can we feed the world without destroying the...
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Lesson 9: Agriculture and Environment
Big Question:
Can We Feed the World Without Destroying the
Environment?
Lesson 9 / ESRM 100 / University of Washington
Some Facts about Agriculture
Agriculture may be the most sustainable human activity.
How much do we actually consume each year? In
America, we consume more than half a ton of food a
year per person.
Farmers feed the more than 6 billion people in the
world (see the U.S. Census Bureau's Population Clock
for the current world population.
Lesson 9 / ESRM 100 / University of Washington
What Do We All Eat?
Most of the world’s food is provided by only 14
plant species.
Lesson 9 / ESRM 100 / University of Washington
Where the World’s Major Crops Grow
Lesson 9 / ESRM 100 / University of Washington
The Bad News About Farming
•Farming often degrades soil.•Fertilizers and pesticides affect soil, water, and
downstream ecosystems.•Irrigation of farmland can lead to salinization (the
buildup of salts in the soil to the point that crops can no
longer grow).•Irrigation can also cause an accumulation of toxic
metals.•Farming can cause a loss of biodiversity.
Lesson 9 / ESRM 100 / University of Washington
Population Growth and Food ProductionAnother big problem: if the human population doubles
as expected, agricultural production will need to double.
Where would we produce all that additional food?
Lesson 9 / ESRM 100 / University of Washington
Dust Bowls and Our Eroding Soils
“The Worst Hard Time” http://www.amazon.com/Worst-Hard-Time-Survived-American/dp/061834697X
; The Plow that Broke the Plains http://www.archive.org/details/PlowThatBrokethePlains1
Lesson 9 / ESRM 100 / University of Washington
Soil Conservation Practices Reduce Erosion
"Soil Erosion in the Palouse River Basin: Indications of Improvement" at
http://wa.water.usgs.gov/pubs/fs/fs069-98/
Lesson 9 / ESRM 100 / University of Washington
The Plow Puzzle
Lesson 9 / ESRM 100 / University of Washington
Long-term Sustainable Agriculture
In areas with a long history of plowing, farmers kept
farming by putting nutrients back into the soil.
They used organic fertilizers, such as animal manure.
Chemical fertilizers were an important development to
increase crop production in the twentieth century.
Lesson 9 / ESRM 100 / University of Washington
Where Eroded Soil Goes
Much of it travels down streams and rivers. 2.7 billion
metric tons per year are deposited in reservoirs, rivers,
and lakes.
Soil eroded from farms carries chemicals that affect the
environment.
Fertilizers carried by sediments increase the growth of
aquatic algae: eutrophication.
Sediment damage costs the United States about $500
million a year.
"The Washington and Oregon Mid-Shelf Silt Deposit and Its Relation to the late Holocene
Colombia River Sediment Budget" at http://wrgis.wr.usgs.gov/open-file/of99-173/
Lesson 9 / ESRM 100 / University of Washington
Making Soils Sustainable
In ideal farming, the amount of soil lost would never be
greater than the amount of new soil produce.
In contour plowing, the land is plowed as horizontally as
possible across the slopes.Contour plowing greatly
reduces soil erosion, and uses less fuel and time.
Lesson 9 / ESRM 100 / University of Washington
Contour Plowing and No-till Agriculture
Mentioned link at http://www.ars.usda.gov/research/publications/publications.htm?seq_no_115=216627
Lesson 9 / ESRM 100 / University of Washington
Conservation Tillage In the United States
Lesson 9 / ESRM 100 / University of Washington
Farm Pests
Lesson 9 / ESRM 100 / University of Washington
How Much Pesticide Do We Release into the Environment? And Where Does It Go?
About 500 million kilograms of 600 different pesticides
were used in the United States in 2005. About 60% of
pesticides found in U.S. waters are herbicides (weed
killers).
Surprisingly little is known about past and present
concentrations of pesticides in major rivers. We need a
wide-scale program to monitor pesticides in our water.
Lesson 9 / ESRM 100 / University of Washington
The Search for a Magic Bullet
To limit pests, many farmers used slash-and-burn
agriculture, where farmers partially cleared small
patches of vegetation in a forest.
Lesson 9 / ESRM 100 / University of Washington
DDT
Bald eagle at Union Bay Natural Area (UW campus) Mt. Rainier in background from www.flickr.com
Lesson 9 / ESRM 100 / University of Washington
Ecological Approaches to Pest ControlResearch to control agriculture pests has shifted to a
fourth stage, biological control, and a fifth stage,
integrated pest management.
Biological control uses predators and parasites to
control pests.
An effective biological control agents is Bacillus
thuringiensis (BT). It causes a disease that affects
caterpillars and the larvae of other insect pests.
Biological control is safe and effective.
Lesson 9 / ESRM 100 / University of Washington
Integrated Pest Management (IPM)
Biological control has not solved all problems. IPM uses
biological control, certain chemical pesticides, surveys,
and careful attention to the timing of planting and
pesticide use.
Lesson 9 / ESRM 100 / University of Washington
Hybrids and GeneticModification: Creating Better CropsGenetic modification is a different approach to pest
management.
People used to think that corn that looked good—a
nicely shaped ear of corn with straight rows of kernels—
was the most productive. Henry Wallace’s experiment
showed that looks had nothing to do with productivity.
Lesson 9 / ESRM 100 / University of Washington
Hybrids and the Green Revolution
Led to the scientific development of hybrid corn.
Hybridization was so successful that it led to the Green
Revolution: development of new strains of maize, wheat,
and rice with greater disease resistance and ability to
grow under poor conditions.
Lesson 9 / ESRM 100 / University of Washington
Biotech
Acreage planted with genetically modified crops (GMCs)
has grown rapidly since 1996.
Lesson 9 / ESRM 100 / University of Washington
Bioteching New Hybrids
The development of hybrids within a species is a natural
phenomenon. However, there are concerns about
superhybrids and superweeds:• Superhybrids may require more water and
fertilizer.• Superweeds may be difficult to control.
There are also concerns about potential effects of
growing GMCs on marginal lands.
Lesson 9 / ESRM 100 / University of Washington
Grazing on Rangelands: An Environmental Benefit or Problem?Almost half of Earth’s land area is used as rangeland.
Much of it is arid and is in poor condition from
overgrazing.
Lesson 9 / ESRM 100 / University of Washington
Overgrazing
Land near streams fares the worst. Retracing the steps
of Lewis and Clark reveals the damage done since their
1804 expedition.
Lesson 9 / ESRM 100 / University of Washington
Organic Farming
Lesson 9 / ESRM 100 / University of Washington
Deserts: What Are They andWhat Causes Them?
Lesson 9 / ESRM 100 / University of Washington
Does Farming Change the Biosphere?
