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! That is 1 in 6 and more some developing nations!

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

hree systems 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)

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 & Changes the Environment Two types of Agriculture Industrialized and Subsistance Agriculture- Only enough food produced for the family, by the family, with none left for profit. Industrialized or high input in some nations Planation agriculture- produces 80% or worlds food –Heavy equipment based on fossil fuels –High input of fertilizer –Monocrop or monoculture farming –Larger yield per acre…

Industrialized agriculture Shifting cultivation Plantation agriculture Nomadic herding Intensive traditional agriculture No agriculture World Food Production Fig p. 279

Industrialized Agriculture- High Input Green Revolution 1950’s----- Step 1 Selectively bred genetically engineered high- yield crops (Corn, wheat, rice). Step 2- High input artificial fertilizer, Pesticide & Water Step 3- Increase the number of crops grown per year on ea acre- depleting soil Agriculture is one of our greatest successes and while also a major source of environmental damage More crops less land has the potential to increase biodiversity- preserve more land… New green revolution.

How Agriculture Changes the Environment Major environmental problems associated with Ag –Soil Compaction- Depletion- 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 –GMO (Genetically modified Organisms) Loss of biodiversity in nature and in our food systems

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

Became a national issue in the US in the 1930s –Intense plowing + drought –Loosened soil blew away during the “Dust Bowl” years

Pesticides required with monoculture agriculture and resistant organisms -artificial organic compounds –DDT, broad-spectrum - Atrazine –Aldrin and dieldrin used to control termites Toxic to humans and has been found in breast milk New 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

Solution Biomimicry Biomimicry- closer your model system to nature the more sustainable it will be. Nature Increases biodiversity- Polyculture Use of natural services of decomposers- fungi and bacteria Producers maintain soils- moisture, nutrients, shade, homes for worms, beetles, nematodes… base for complex food webs.

Alternatives….Contour Plowing One of the most effective ways to reduce soil erosion, Polyculure, Drip irrigation

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!

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