Food, Soil, and Pest Management
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Transcript of Food, Soil, and Pest Management
Chapter 12
We can sharply cut pesticide use without decreasing crop yields by using a mix of cultivation techniques, biological pest controls, and small amounts of selected chemical pesticides as a last resort (integrated pest management).
What is a pest – interferes with human welfare
Natural enemies—predators, parasites, disease organisms—control pests In natural ecosystems In many polyculture agroecosystems
Pesticides Insecticides – insects killers Herbicides – weed killers Fungicides – fungus killers Rodenticides – rat and mouse killers
Herbivores overcome plant defenses through natural selection: coevolution
First-generation pesticides-natural chemicals from plants
Second-generation pesticides Paul Muller: DDT Nobel Prize 1948 Benefits versus harm
Broad-spectrum agents – toxic to many pests and non-pest species. Chlorinated hydrocarbons: DDT, organophosphates : malathion, parathion
Selective or narrow spectrum agents - Persistence – length of time they remain
deadly in the environment for years, biologically magnified in food webs
Biologist : DDT use was increasing to control mosquitoes
Silent Spring - 1962 Potential threats of
uncontrolled use of pesticides
Gave impetus to the US environmental movement
Save human lives prevented deaths from malaria, typhus and bubonic plague : at least 7 million people
Increases food supplies and profits for farmers protect 55% of the world’s food supply. Profit $1:$4
Work quickly, long shelf life, easily shipped and applied
Health risks are very low relative to their benefits
New pest control methods: safer and more effective
Accelerate the development of genetic resistance, 5 to 10 years, sooner in
the tropics
Financial treadmill
Kill natural predators and parasites that help control
Only 0.1-2% of the pesticide applied by aerial or ground spraying reaches
the target pest. Rest pollutes air, water, harm wild life, affect human
health
Expensive for farmers
Some insecticides kill natural predators and parasites that help control the
pest population
Pollution in the environment
Some harm wildlife
Some are human health hazards
David Pimentel: Pesticide use has not reduced U.S. crop loss to pests Loss of crops is about 31%, even with 33-
fold increase in pesticide use High environmental, health, and social
costs with use, $5-10 in damages for every $1 spent
Use alternative pest management practices could halve the use of chemical pesticides on 40 major US crops
Pesticide industry refutes these findings Campbell soup tomatoes in Mexico, Rice in
Indonesia, Sweden
Best-selling herbicide (Roundup), Monsanto
Advantages – does not harm living things, degrades into harmless substances within weeks
Disadvantages - resistant weeds , expensive to develop other pesticides
1955: Dieldrin sprayed to control mosquitoes
Malaria was controlled
Dieldrin didn’t leave the food chain
Domino effect of the spraying
Happy ending
U.S. federal agencies EPA USDA FDA
Effects of active and inactive pesticide ingredients are poorly documented
Circle of poison, boomerang effect – residues of banned chemicals exported to other countries may come back on food, winds carry persistent pesticides such as DDT
1998 – 50 countries developed treaty that requires exporting countries to have consent from importing countries for exports of 22 pesticides , 5 industrial chemicals
2000 – 100 countries signed to phase out 12 of the most hazardous persistent organic pollutants (POP’s), 9 of them hydrocarbons (DDT)
United States has not signed this agreement
Fool the pest : rotate crops, adjust plant times
Provide homes for pest enemies
Implant genetic resistance : GMO’s
Bring in natural enemies : natural predators
Use insect perfumes
Hormones Scald them
Integrated pest management (IPM) Coordinate:
cultivation, biological controls, and chemical tools to reduce crop damage to an economically tolerable level
Disadvantages expert knowledge
Control prices – keep artificially low Provide subsidies – price supports, tax
breaks, subsidies for 31% of global farm income Developed : $280 billion /year Substitute traditional subsidies with ones
that promote sustainable farming practices Subsidies to fishing – promotes destructive
fishing practices Let the marketplace decide
United Nations Children’s Fund (UNICEF) suggests these measures. Can be done at an average annual cost of $5-10 / child Immunizing children against childhood
diseases Encourage breast-feeding Prevent dehydration in infants and children Prevent blindness – Vitamin A capsule
(75c/child) Provide family planning services Increase education for women
Sustainable food production will require reducing topsoil erosion, eliminating overgrazing and overfishing, irrigating more efficiently, using integrated pest management, promoting agrobiodiversity, and providing government subsidies for more sustainable farming, fishing, and aquaculture.
Producing enough food to feed the rapidly growing human population will require growing crops in a mix of monocultures and poly cultures and decreasing the enormous environmental impacts of industrialized food production.
Soil conservation, some methods Terracing Contour
planting Strip cropping
with cover crop Alley
cropping, agroforestry
Windbreaks or shelterbeds
Conservation-tillage farming
No-till Minimum
tillage
Identify erosion hotspots
Organic fertilizer Animal manure – dung , urine Green manure – freshly cut, growing green
vegetation Compost microorganisms to break down organic
waste Commercial inorganic fertilizer active ingredients
Nitrogen Phosphorous Potassium
Crop Rotation
Soil salinization Prevention Clean-up
Desertification, reduce Population growth Overgrazing Deforestation Destructive forms
of planting, irrigation, and mining
Reduce irrigation
Switch to salt-tolerant crops (such as barley, cotton, and sugar beet
Flush soil (expensive and wastes water
Stop growing crops for 2–5 years
Install underground drainage systems (expensive)
Paul Mader and David Dubois 22-year study Compared organic and conventional farming
Benefits of organic farming little or no use of synthetic pesticides,
fertilizers or genetically engineered seeds, fields free for 3 years
livestock raised without genetic engineering
Fig. 12-32, p. 308
SOLUTIONS
Organic Farming
Improves soil fertilityReduces soil erosionRetains more water in soil during drought years
Uses about 30% less energy per unit of yield
Lowers CO2 emissionsReduces water pollution by recycling livestock wastes
Eliminates pollution from pesticidesIncreases biodiversity above and below ground
Benefits wildlife such as birds and bats
Effect of different fertilizers on nitrate leaching in apple trees calcium nitrate and alfalfa residues,
composted chicken manure, integrated approach (combined)
Less nitrate leached into the soil after organic fertilizers were used – 4.4 to 5.6 times less
Annual Wheat Crop
Plant
Roots of a tall grass prairie
plant
Better at using water and nutrients
Supports local economies Does not have to be transported far –
reduces greenhouse gas emissions, 5 to 17 times less
Reduces environmental impact on food production – grow organic food or buy organic food grown locally
Community-supported agriculture (CSA)