Chapter 12: Effects of Agriculture on the Environment

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!

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

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

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= 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 How much does your drink really weigh?

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 1,600 2,200 2,800___ Food groups Milk/dairy 222 Protein 2 23 Vegetables 345 Fruit 234 Grains 6911 Fats 223

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.

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

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

hree systems T hree 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)

T hree 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 Only 14 plants & 8 animal species supply ~90% of world’s food

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

Aquaculture World’s 3 rd 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 purse-seine drift net aquaculture trawl bag

Aquaculture Facilities

Aquaculture

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

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

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

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

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

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

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

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

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

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!

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 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 The History of Pesticides

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

Control of oriental fruit moth done by parasitic wasp.

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