The document discusses several key issues related to water pollution from agriculture:
1) Factory farming has led to large-scale livestock and poultry operations that produce over 500 million tons of manure per year, far more than can be absorbed by crops as fertilizer. The excess manure runs off into waterways.
2) Nitrogen fertilizers have revolutionized farming but are often over-applied, with only 30-50% used by crops. The excess enters water as nutrient pollution.
3) This excess nitrogen causes eutrophication, stimulating excessive algae growth. When the algae die off, their decomposition uses up oxygen, leading to hypoxic "dead zones" that cannot support aquatic
7. Clean Water Act (1972)
• Addresses point-source pollution.
• Set benchmarks, deadlines, and penalties for
non-compliance.
• Not perfect but is at least an attempt to
address the problem.
– We are FARbetter off today.
9. Agricultural Pollutants
• The latest EPA National Water Quality
Inventory indicates that agriculture is the
leading contributor to water quality
impairments, accounting for 60 percent of
contamination in rivers and lakes.
• Why?
– Most agricultural pollution is considered non-
point source and therefore not subject to the
Clean Water Act.
– The way agriculture is practiced has changed
greatly in the last 50 years.
• Rise of Factory Farming.
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14.
15.
16.
17. Changing Market Conditions
• In the 1970's the top 5 meat packing companies
processed about 25% of the market.
– Today the Top 4 (Tyson, Cargill, Swift, and National
Beef) process more than 80% of the meat we eat.
• In the 1970s, there were thousands of
independent slaughterhouses nationwide
producing the majority of beef sold.
– Today, we have only 13.
• Vertical Integration: When a company assumes
control of multiple stages in the production
process.
18.
19. What to Do With the Poo?
• On a small diversified farm manure is
used as fertilizer for crops.
– Small enough amounts of manure that it
can be broken down naturally to provide
the plants with nutrients.
• Large-scale commercial livestock and
poultry operations produce an estimated
500 million tons of manure each year.
– More than three times the sewage
produced by the entire U.S. human
population.
– Funneled into waste lagoons which often
leak.
• Becomes highly concentrated.
– 75 X More Concentrated than raw human
sewage.
• Then sprayed on fields at levels far byond
what can be absorbed.
– Runoff!
25. Quick Review: Elements vs. Compounds
• Elements: Smallest division of matter. You
can’t break matter down into any smaller
chemically different pieces.
– All material on earth is made up of 92 naturally
occurring elements.
• Compounds: Two or more different elements
bond together to form compounds.
– These compounds often have very different
chemical and physical properties than their
component elements.
30. Nitrogen
• When it comes to nutrient
pollution the element we
are most concerned with
is Nitrogen.
• Elemental nitrogen is a
colorless, odorless, tastele
ss, and mostly inert (non-
reactive) gas.
• Makes up 78.09% of
Earth’s atmosphere.
31. Nitrogen
• Nitrogen itself is a fairly
abundant element here
on earth.
• However, the vast
majority of that
nitrogen is in the form
of N2 an inert gas.
• N2 gas cannot be used
by plants directly.
32. Nitrogen Compounds
• Plants can only make use of
Nitrogen when it is in
chemical compounds such as
NH3 (Ammonia) and NO3
(Nitrate).
• These compounds are fairly
rare in nature.
• For this reason Nitrogen is
often a limiting nutrient in
ecosystems.
– Gets used up quickly (and
replenished slowly).
– When you run out plants stop
growing.
33.
34. Nitrogen and Traditional
Agriculture
• The issue of nutrient (Nitrogen) depletion
has plagued Agriculture for centuries.
– There is a limited amount of useable Nitrogen
in the soil and it replenishes slowly.
– Each planting season removes Nitrogen from
the soil and it is carried away with the crop.
• For many years farmers dealt with this
problem in 3 main ways.
– Move: Find new nutrient rich land to farm.
– Fertilize: Spread animal waste (manure) that
is high in Nitrogen.
– Crop Rotation: Alternate between planting a
crop that uses lots of nutrients, like corn, and
legumes (soy beans) that replenish nitrogen.
• Soy Beans have sacs of Nitrogen fixing bacteria
that convert atmospheric nitrogen into useable
compounds.
35. The Birth of Nitrogen Fertilizers
• During WW2 German chemists
Fritz Haber and Carl Bosch, in
an attempt to make
explosives, developed a
process to synthetically create
Nitrates and Ammonia.
• This technology revolutionized
how agriculture was practiced -
these synthetic nitrogen
compounds could be used as
fertilizer.
• “The Green Revolution”
36. Too Much Nitrogen
• With the availability of cheap
Nitrogen fertilizers many farmers
switched over.
– These are often over-applied in an
attempt to generate the highest
possible yield.
– Also creates an issue of excess manure.
• It is estimated that nitrogen fertilizers
(both artificial and manure) are
grossly over-applied.
– Only 30-50 Percent of the Nitrogen
fertilizer applied by US farmers is used
by the target crop plants.
– The rest enters the environment as
nutrient pollution.
– More is not necessarily better! Use
fertilizer more efficiently.
38. Eutrophication
• Remember: In most aquatic systems Nitrogen
acts as a Limiting Nutrient.
– The ecosystem can only support a certain number
of plant (algae) species.
– You can only have as many plants as there is
nitrogen to support them.
• When nitrogen-rich runoff from factory-scale
livestock operations and farm fields enters a
body of water it greatly alters the nutrient
balance.
– Greatly increases the amount of nitrogen.
39. Eutrophication
• Eutrophication:
Process in which a
body of water
receives excess
nutrients stimulating
excessive plant
growth.
– Nitrogen is no longer
the limiting nutrient.
– Algae Blooms.
41. Think back to Biology?
• What is photosynthesis?
– Occurs in plants.
– Converts Sunlight (energy), Carbon Dioxide, and
Nutrients into Complex Organic Molecules and
Oxygen.
• What is cellular respiration?
– Occurs in animals.
– Breaks down Complex Organic Molecules and
Oxygen into Energy and Carbon Dioxide
42.
43. Hypoxia
• Eutrophication produces lots of organic material.
When this material decomposes it uses up
Oxygen and produces Carbon Dioxide.
• Hypoxia: Water that has very low, or no dissolved
oxygen.
– Incapable of supporting life.
– Result of decaying organic material.
– Generally happens in deep water, at night, or during
droughts.
• Causes fish kills and can lead to dead zones.
– Dead zone in Gulf of Mexico is 8,500 square miles.
44.
45.
46.
47. Deadzones
• Deadzone in Gulf of
Mexico is 8,500 square
miles.
• Hypoxic Zones occur
worldwide.
• Map
• Major threat to the
fishing industry.