This document discusses the major concerns with conventional agriculture, including water pollution from animal waste and fertilizers, water and land use changes, impacts on animals and ecosystems, and human health issues. It then explores alternatives like organic agriculture, agroecology, and integrated pest management. Specifically, it examines the problems of nitrogen pollution from fertilizers and animal waste, large-scale livestock production, and proposes solutions like using legumes for natural nitrogen fixation and moving toward smaller, more sustainable farms and food systems.

1. Agriculture
What are some concerns about
conventional agriculture?

2. Goals:
• To understand some of the major concerns with
conventional agriculture, and why conventional
agriculture began and prospered
• To explore how growing corn and raising meat
affect ecosystems, and how to combat some of
these concerns through agroecology practices
• To consider our future options for growing food for
a planet of 9+ billion

3. Major Concerns with Conventional
Agriculture (an incomplete list…)
• Water pollution – animal waste, pesticides, herbicides,
fertilizers
• Water use - dams, irrigation canals, groundwater
• Land use changes – habitat loss, erosion, wetland loss,
desertification
• Animals – animal welfare, waste, medication overuse,
feed requirements, introduction of invasive species
• Genetic modification & ownership of plant genomes
• Energy use & greenhouse gases
• Human health

4. What is conventional agriculture?
• Large farms
• Lots of inputs: $,
fertilizer, energy,
water, pesticides
• Monocultures

5. What is organic agriculture?
• A farm using methods that avoid most synthetic
materials (pesticides and antibiotics)
• There ARE large, industrial-scale organic operations
• Many small-medium sized farmers cannot afford the
organic label
vs

6. What is agro-ecology?
The application of ecology to the design and
management of sustainable agro-ecosystems
Agro-ecology is a whole-systems approach to
agriculture and food systems development – it
incorporates
– Traditional knowledge
– Local food systems experience
– Sustainable agriculture practices

7. Green
Revolution
1. Plant monocultures of new hybrids (disease
resistant and higher yielding)
2. Produce high yields by using chemical inputs &
water
3. Mechanize irrigation, planting, harvesting
Started in 1950s with development of fertilizers and
wide-spread availability of pesticides and farm
equipment

8. Africa: the Green Revolution’s next iteration
Agricultural companies are buying up or leasing large tracts of land in Africa to grow soy, corn,
and other export crops, often displacing small farmers.

9. Let’s look at one problem…nitrogen
from fertilizers and animal waste
1900 1960 1980 20001920 1940
50
100
150
200
0
TotalNfixation(TgNyr-1)
4
3
2
1
5
0
6
HumanPopulation(billions)
1900 1960 1980 20001920 19401900 1960 1980 20001920 1940
50
100
150
200
0
TotalNfixation(TgNyr-1)
4
3
2
1
5
0
6
4
3
2
1
5
0
6
HumanPopulation(billions)

10. Source: Compiled from Landsat Thematic Mapper satellite imagery, Iowa Dept. of Natural Resources.

11. Nitrogen…so what?
• Plants and animals
need nitrogen
• But…there can be too
much of a good thing!
• Too much nitrogen
results in:
eutrophication of
aquatic systems
…which leads to…
There is both cultural (human) and
natural eutrophication

12. • 1960s = 40 global dead zones
• Today = more than 400

13. Why care about nitrogen?
We should care because it causes…
• Water pollution (eutrophication, dead zones)
• Acidic precipitation (rain, snow, fog)
• Climate change (nitrous oxide)
• Air pollution (nitric oxide=smog)

14. Agroecology solution: legumes!
Bacteria in the root nodules
of legumes naturally fix
inorganic atmospheric
nitrogen , providing
nutrients to the plant while
receiving sugars in return

15. Many other chemicals are used (that
we aren’t talking about today)!
• Pesticides/herbicides such as atrazine and
neonicotinoids
• Genetically engineered crops and pesticides –
“Roundup Ready”

16. Agroecology solution: Integrated Pest
Management
–Disrupting Reproduction
• Female Sex Pheromones
• Male Sterilization
–Natural Predators

17. Nitrogen also comes from animal waste…

18. CAFOs (Concentrated Animal Feeding Operations)
In the US, the percentage of
our meat products that
come from factory farms:
• 99.9% of chickens for meat
• 97% of laying hens
• 99% of turkeys
• 95% of pigs
• 78% of cattle
• http://www.factoryfarmma
p.org/

19. Global Impacts of
Livestock
• Produces 18% of
greenhouse gas
emissions
• Uses 30% of the
Earth’s total land
surface
• Good videos:
Fresh, Food Inc.,
King Corn,
Frontline’s Harvest
of Fear
A double quarter pounder: uses 3000 liters of water

21. Worldwide Picture
• As income increases, meat consumption also increases
• Consequences: water, chemical inputs to grow grain,
animal abuse, transportation costs, monocultures

22. Fig. 8.5
Benefits
of eating
lower on
the food
chain

23. Agroecology solution
• Smaller farms with fewer animals
• Using animal waste as fertilizer is OK in small
amounts
• Rotating animals
• Eating less meat!
Note: if you eat dairy
you are still part of the
meat system

24. Organic vs Conventional
• Organic yields match conventional yields &
outperforms conventional in years of drought
• Organic farming systems build rather than
deplete soil organic matter, making it a more
sustainable system
• Organic farming uses 45% less energy
• Conventional systems produce 40% more
greenhouse gases
• Organic farming systems are more profitable
than conventional

25. Can organic farming “feed the world”?
Some takeaway considerations:
– We waste 30-40% of our food
– There are currently enough calories produced for
everyone (2,700 calories/person)
– Of the ice-free land on earth, almost 40% is already
dedicated to agriculture
Perhaps the question should be
instead: should conventional
agriculture feed the world?

26. Solution: Agroecology
Recognize the farm as an ecosystem:
– Grow lots of different crops, use heritage seeds
– Rotate crops & animals
– Implement integrated pest management
– Use legumes or small amounts of animal waste for
fertilizer
– Use wetlands to reduce runoff and eutrophication

27. What you can do:
Buy local, buy organic, ask questions!
www.LocalHarvest.org – Find a CSA
www.EatWellGuide.org - Find local farms