1. Chapter 12: Effects of Agriculture on the Environment

2. Food Insecurity Root cause Poverty Undernutrition Malnutrition Anemia
Goiters
Famine
Marasmus and Kwashiorkor
M = diet low in calories and protein
K = severe protein deficiency
1 billion do not get enough to eat!

3. US “Obesity Epidemic” Ogden et. al. (JAMA 288, 14; Oct. 2002)
Our National Eating Disorder
US “Obesity Epidemic” Ogden et. al. (JAMA 288, 14; Oct. 2002)
1.6 face health problems because they eat too much!

4. Health Effects Obesity Menstrual irregularities Diabetes
High blood pressure
High cholesterol
Osteoarthritis
Decreased mobility

5. How much does your drink really weigh?
If you drank one 12oz.can of soda daily and did not increase your physical activity, what would happen?
Average 12oz soda= 160 calories
160 calories X 365 days= 58,400 calories per year
3,500 calories = 1 pound
58,400 calories divide by 3,500 calories=
16.69 pounds of weight gain
What would happen if you drank one 44oz Big Gulp daily?
One 44 oz Big Gulp = 513 calories
Answer: 53.5 pounds

6. How many Food Pyramid daily servings do YOU really need?
Most women Active women Active men
Children (2-6) Most men Teen Boys
Older children
Teen girls
Total Calories , , ,800___
Food groups
Milk/dairy
Protein
Vegetables
Fruit
Grains
Fats

7. Five key nutrition messages:
More fruits and vegetables.
More whole grains, fewer processed foods overall.
More water, fewer “caloric” drinks.
Replace bad fats with “good” fats.
Be aware of
portion sizes.

8. Physical Activity Pyramid
20-40 minutes
3-4 times per week
aerobic fitness
45-60 minutes,
3-4 times a week
for weight loss
30 minutes
everyday for health
Children up to 18 years should have a minimum of 60 minutes daily of physical activity

9. Health Effects Shortness of breath Heart disease
Liver and kidney problems
Cardiac arrest and/or death
Gallbladder disease
Certain types of cancer

10. Three systems humans depend on for their food supply.
Croplands supply 77% of the grain using 11% of the land
Rangelands provide 16% of meat production Using 29% land
Ocean fisheries 7% (6% of protein in human diet)

11. Only 14 plants & 8 animal species supply ~90% of world’s food
Three grain crops that provide “more than half of the calories people consume”. Think about why this might be so. Consider advantages and disadvantages for this worldwide choice.
Wheat, rice, corn

12. 1 cow produces as much waste as 16 humans
Number of people worldwide who will die as a result of malnutrition this year: 20 million
Number of people who could be adequately fed using land freed if Americans reduced their intake of meat by 10%: 100 million
Percentage of corn grown in the U.S. eaten by people: 20
Percentage of corn grown in the U.S. eaten by livestock: 80
Percentage of oats grown in the U.S. eaten by livestock: 95
Percentage of protein wasted by cycling grain through livestock: 90
How frequently a child dies as a result of malnutrition: every 2.3 seconds
Pounds of potatoes that can be grown on an acre: 40,000
Pounds of beef produced on an acre: 250
Percentage of U.S. farmland devoted to beef production: 56
Pounds of grain and soybeans needed to produce a pound of edible flesh from feedlot beef: 16

13. Aquaculture World’s 3rd largest food producing system
Aquaculture Concentration of aquatic species
Cmmercial harvesting, Industrial fishing fleets use sonar, gps… vacuuming the seas.
Decreasing biodiveristy and degrading ecosystem
trawl bag
aquaculture
drift net
purse-seine

14. Aquaculture Facilities

15. Aquaculture

16. How Agriculture Changes the Environment
Agriculture is one of our greatest successes and while also a major source of environmental damage.
Major environmental problems associated with Ag
Soil erosion
Sediment transport and deposition downstream
On-site pollution from overuse and secondary effects of fertilizers and pesticides
Off-site pollution of other ecosystems, of soil, water and air

17. How Agriculture Changes the Environment
Major environmental problems cont.
Deforestation
Desertification
Degradation of aquifers
Salinization of soil (“Salting”)
Accumulation of toxic organic compounds
Loss of biodiversity

18. Our Eroding Soil
When land has been cleared of its natural vegetation, the soil begins to lose its fertility
Erosion is tied to the loss of particles that help maintain presence of plant nutrients
Became a national issue in the US in the 1930s
Intense plowing + drought
Loosened soil blew away during the “Dust Bowl” years

19. Dust Bowl image – historical file photo

20. Our Eroding Soil The land that became the Dust Bowl had been prairie
Deep rooted grasses had held soil in place
After plowing soil becomes exposed to rain and wind effects
When original vegetation (“canopy cover”) is cleared soil changes
Soil exposed to sunlight speeds the rate of decomposition

21. Our Eroding Soil
Traditionally declines in soil fertility were treated using organic fertilizers
Animal manures, worm castings
In the 20th century crop production increased
Chemical fertilizers
Adding nitrogen and phosphorous to the soil was easily achieved

22. Where Does Eroded Soil Go?
A lot of it travels down streams and rivers
Deposited at their mouths
Fills in water ways
Damages fisheries and coral reefs
Sedimentation has chemical effects
Enrichment of waters, eutrophication
Transport of toxic chemical pesticides

23. Making Soils Sustainable
Soil forms continuously
But very slowly
1mm of soil formation takes years
To be truly sustainable soil lost should equal amount of new soil produced

24. Alternatives….Contour Plowing One of the most effective ways to reduce soil erosion
Contour planted slopes

25. Controlling Pests Pests are undesirable:
Competitors, parasites, and predators
In agriculture pests are mainly
Insects, nematodes, bacterial and viral diseases, weeds and vertebrates.
Loss can be large
Estimated at 1/3 of potential harvest and 1/10 of the harvested crop

26. Controlling Pests
Because a farm is maintained in a very early stage of ecological succession and enriched by fertilizers and water
It is a good place for crops
AND early-successional plants (weeds)
Weeds compete for all resources
Light, water, nutrients, and space to grow. Weed are also early successional plants as well!

27. The History of Pesticides
Pre- Industrial Revolution methods
Slash and burn agriculture
Planting aromatic herbs that repel insects
Second stage began in the 1930
Petroleum based sprays and natural plant chemicals (e.g., nicotine)
Third stage was the development of artificial organic compounds
DDT, broad-spectrum
Aldrin and dieldrin used to control termites
Toxic to humans and has been found in breast milk

28. The History of Pesticides
Forth stage is a return to biological and ecological knowledge.
Biological control - the use of predators and parasites to control pests
The use of Bacillus thuringiensis (BT) is the most widely used BioInsecticide
Predatory insects such as ladybugs, or parasitic wasps
Proven safe and effective
Sex pheromones (chemicals released to attract opposite sex) used as bait in traps to interrupt reproductive cycle

30. Integrated Pest Management
Fifth stage
IPM uses a combination of methods
Biological control
Chemical pesticides
Methods of planting crops (mixed fields)
Goal can be control, but never complete elimination of pests
Economically makes sense
Does less damage to ecosystem, soil, water and air

31. Control of oriental fruit moth done by parasitic wasp.

32. Monitoring Pesticides in the Environment
World pesticide use exceeds 2.5 billion kg
US use exceeds 680 million kg
$32 billion worldwide, $11 billion in US
Once applied may decompose in place or be carried by wind and water
Breakdown products can also be toxic
Eventually fully decompose but can take a long time