Chapter 15

1. Chapter 15 Agriculture and Pest Management Agriculture Methods • Slash and Burn Agriculture. • Small areas - usually in tropics • Burning returns nutrients to soil • polyculture practiced = plant many different types of plants • Land recovers - forest re-invades • Labor Intensive Agriculture • Occurs under three conditions • 1. When topography won’t allow mechanization • 2. When crop won’t allow it • 3. Where cost is prohibitive and labor cheap

2. Chapter 15 Mechanized Agriculture • Typical of North America, Europe and former Soviet Union • Requires large tracts of land • Special varieties of plants that can be harvested by mechanical means (hybrids, G.E. species) • monoculture = planting only one species of plants on large areas • Can cause soil erosion and depletion of soil nutrients • Cheap fuel - energy from fossil fuels replaces labor • Has significantly increased food production

3. Chapter 15 Energy Versus Labor • Mechanized agriculture substitutes energy from petroleum for human labor • 1913 - took 135 hours of labor to produce 2,500 kilograms of corn • 1980 - took 15 hours to produce 3500 kilograms of corn • Energy from petroleum is used for: • Tilling, planting harvesting, pumping water, • To produce fertilizers, pesticides - herbicides, fungicides and insecticides • Changes in the cost or availability of fuel will impact on the worlds ability to feed itself!!!! • Broad implication of US dependence on foreign oil

4. Chapter 15 Impacts of fertilizers • 25% of the world’s crop yields is attributed to the use of fertilizers - no fertilizers- 25% decrease in food • oil costs - poverty- hunger - fertilizer paradox • Macro nutrients – nitrogen (N), phosphorus (P), potassium(K)– also C,H,O but… • Micronutrient – copper zinc, iron, magnesium, manganese, boron, etc • Why do we have to fertilize? Where do the Macro nutrients and micronutrients go?

5. Chapter 15 Inorganic fertilizers do not replace organic matter ! • Why is organic matter important? • Humus • prevents compaction, makes poor spaces • lowers pH • serves as food for bacteria and earthworms • holds moisture • holds nutrients and provides slow release of them, less runoff of pollutants  • Total dependency on inorganic fertilizers causes adverse changes in soil properties.

6. Chapter 15 Pesticides • Pesticide = any chemical used to kill or control the populations of unwanted fungi, animals, or plants (pests). Weeds = unwanted plants • Herbicide = kills plants • Insecticide = kills insects • fungicide = kills fungi • rodenticide = kills mice and rats • Target organisms = pests you desire to kill • nontarget organisms = other organisms killed by a pesticide in addition to targeted pest including many beneficial organisms

7. Chapter 15 Insecticides • Natural insecticides • Nicotine • Pyrethrum - chrysanthemums • Rotenone • Synthetic organic insecticides • 1867 - Paris green - acetate and arsenide • 1942 - DDT - dichlorodiphenyltrichloroethne • DDT saved 5 million lives in first ten years of uses. BUT insects became tolerant and DDT biomagnified !!!!

8. Chapter 15 Three Types of Synthetic Insecticides • 1. Chlorinated hydrocarbons • Examples: DDT, aldrin, dieldrin, toxaphene, chlordane, mirex, kepone  • Mode of action – thought to be a neurotoxin, but mode(s) of action is / are not fully understood • Very persistent- half life 10-15 years • Banned in U.S. but still used in developing countries—problem?

9. Chapter 15 2. Organophosphate • Examples: Chlorpyrifos (Dursban) Diazinon (Spectracide), Malathion •  Mode of action - cholinesterase inhibitor •  Short half lives, but more toxic to humans and require more frequent applications 3. Carbamates • Examples: carbaryl (Sevin) •  Mode of action - cholinesterase poison • Half life - short - hours/days

10. Chapter 15 Problems With Pesticide Use • 1. Persistence - hard pesticides • Global transport - found all over the world • Bioconcentration, bioaccumulation, biomagnification (amplification) • 2. Insects build up resistance • 3. Impacts on non-target beneficial organisms • 4. Short term and long term health problems of farm workers

11. Chapter 15 Reasons Pesticides Are Widely Used • 1. Use of Pesticides has increased about of food that can be grown worldwide • 2. Economics - cost of pesticides is less than the increased value of crops produced • 3. Needed to control disease organisms

12. Chapter 15 Organic Farming • Prior to availability of fertilizers and pesticides all farming was organic • Organic farming is use of animal manure, crop rotation, mixture of crops, manual labor or biocontrol to kill pests • “Organically grown” vegetables, grains and meat are gaining in popularity because of health concerns over use of pesticides and because of nutrition concerns

13. Chapter 15 Integrated Pest Management • Integrated Pest Management = use of a variety of methods to control pests rather relying on use of pesticides alone - Integrated use of chemical, physical and biological methods of controlling pests • Examples: Use of sex attractants (pheromones), male sterilization, release of predators and parasites, pest resistant crops, use of natural pesticides, modification of farming techniques