1. Soil
Ch 13 and CIE sources

2. The changing face of agriculture
10,000 years ago, people in different cultures began to raise plants for food and to domesticate animals
Agriculture: practice of raising crops and livestock for human use and consumption
Cropland: land used to raise plants for human use
Rangeland: land used for grazing livestock
Land devoted to agriculture now covers 38% of Earth’s land

3. The changing face of agriculture
Traditional agriculture: uses human and animal power
Hand tools, simple machines
Polyculture: different crops are planted in one field
Industrial agriculture: uses large-scale machines and fossil fuels to boost yields
Also uses irrigation, fertilizers, and pesticides
Monoculture: planting a single, genetically similar crop
More efficient but reduces diversity, is disease prone
Narrows the human diet
Used in industrial agriculture

4. Industrialized Crop Production Causes Soil Erosion
Industrialized agriculture, high-input agriculture (intensive) produces 80% of world’s food supply
Uses heavy equipment and large amounts of fossil fuels, water, commercial fertilizers, pesticides, and financial capital.
Primarily monocultures – single crop in one area.
Goal is to steadily increase crop yield, Ex Corn

5. The effects of industrialized agriculture
Industrial agriculture has allowed food production to keep pace with population growth
But it has many bad environmental and social effects
Benefits: increases crop yields while reducing pressure to develop natural areas for new farms
Drawbacks: water, fossil fuels, fertilizers, pesticides worsen pollution, erosion, and desertification
Requires far more energy than traditional methods
Displaces low-income farmers who can’t afford the technology, forcing them to move to cities

6. Sustainable agriculture
Suitable farmland is disappearing
We must improve the efficiency of production
It is better to raise animals and crops that pollute less, require less fuels, and have less impact on natural systems
Sustainable agriculture: maintains healthy soil, clean water, and genetic diversity
Treats agricultural systems as ecosystems
Low-input agriculture: uses smaller amounts of
Pesticide, fertilizers, growth hormones, antibiotics, water, and fossil fuels than industrial agriculture

7. Regional differences in soils affect agriculture
In rainforests, rain leaches minerals and nutrients, reducing their accessibility to roots
Rapid decomposition of leaf litter results in a thin topsoil layer with little humus
Farming quickly depletes the soil’s fertility
Swidden agriculture: traditionally used in tropical areas
After cultivation, a plot is left to regrow into forest
Temperate prairies have lower rainfall and less nutrient leaching, resulting in higher fertility

8. Differences in regional agriculture
Swidden agriculture is not sustainable at high population densities
Fertile prairies can be farmed repeatedly if protected

9. The Dust Bowl In late 1800 and early 1900, farmers and ranchers:
Grew wheat, grazed cattle
Removed native grasses
Dust Bowl: 1930s drought and erosion caused “black blizzards” of sand
Thousands of farmers left their land
Relied on governmental help to survive

10. The Soil Conservation Service (SCS)
Started in 1935 by the Congress, the SCS works with farmers to develop conservation plans for farms
The SCS is now named the Natural Resources Conservation Service
Other countries started their own conservation agencies
No-till farming in Argentina, Brazil, and Paraguay
Grassroots organizations helped by agronomists and government extension agents

11. Agricultural subsidies affect soil degradation
Theoretically, the market should discourage farmers and ranchers from degrading the land
But degradation is slow, and farmers can’t afford to lose money
Many governments spend billions to subsidize agriculture
20% of a U.S. farmer’s income comes from subsidies
Pros of subsidies: protect farmers from uncertain weather
Cons of subsidies: encourage farming of vulnerable land
Producing more food than needed, driving prices down
Farmers should buy insurance against losses

12. Seed banks conserve wild genes
Industrial agriculture’s use of genetically similar crops has led to efforts to conserve wild relatives of crops
Wild crops contain genes will will need in the future
Seed banks: institutions that store seed types
Seeds are collected, stored, and periodically planted
Wild crops must not be allowed to interbreed with genetically modified crops
To prevent introduction of GM crops into wild populations

13. The Green Revolution increased yields
Green revolution: drastically increased food through new
Technology
Crop varieties
Farming practices
Spread to the developing world in the 1940s
Wheat, rice, corn
Norman Borlaug won the Nobel Peace Prize for his work

14. U.S. programs promote soil conservation
Conservation Reserve Program (1985): farmers are paid to put highly erodible land in conservation reserves
Trees and grasses are planted instead of crops
Each dollar spent saves 1 ton of topsoil
Generates income for farmers
Improves water quality and provides habitat
$1.8 billion/yr protects 30–40 million acres
The 2008 Farm Bill limits protection to 32 million acres
But funds 14 other programs
International agencies also promote sustainable agriculture

15. Sustainable approaches to irrigation
Match crops and climate
Don’t plant water-guzzling crops in dry areas
Plant beans or wheat, not rice
Subsidies make irrigation water artificially cheap
Drip irrigation delivers water directly to plants
Drip irrigation works best on smaller plots with perennial plants (fruit trees)

16. Fertilizers boost yields
Fertilizers: substances containing essential nutrients to enhance crop production
Inorganic fertilizers: mined or synthetically manufactured mineral supplements
Organic fertilizers: the remains or wastes of organisms
Manure, crop residues, fresh vegetation (green manure)
Compost: produced when decomposers break down organic matter

17. Inorganic fertilizers cause problems
Inorganic fertilizers have boosted production
But also severely pollute
Leaching and runoff of inorganic fertilizers causes:
Groundwater contamination
Dead zones in water systems
Air pollution from evaporated nitrates
Inorganic fertilizer use has skyrocketed worldwide

18. Sustainable fertilizers
Sustainable approaches to fertilizing delivers nutrients directly to plant roots and avoids overapplication
Add fertilizers to drip irrigation water
No-till or low-till systems inject fertilizers with seeds
Monitor soil nutrients and add only when they are low
Strips of vegetation along field edges and streams capture nutrient runoff
Organic fertilizers add nutrients and organic matter
Improving soil structure, nutrient and water retention
Integrate inorganic and organic fertilizer systems

19. Pesticides control pests
Pest: any organism that damages valuable crops
Weed: any plant that competes with crops
Pests and weeds especially threaten monocultures
Pesticides: poisons that target pest organisms
Insecticides kill insects, herbicides kill plants, and fungicides kill fungi
75% of pesticides are applied to agricultural land
Exposure to synthetic pesticides can cause health problems for humans and other organisms
Pesticides also kill many nontarget organisms

20. Pests evolve resistance to pesticides
Pesticides lose effectiveness as pests evolve resistance
Individuals that can metabolize and detoxify a pesticide survive and pass these genes to their offspring
As the population increases, pesticides lose their effectiveness
Pesticide treadmill: chemists increase the toxicity of pesticides to compete with resistant pests
Many species (green peach aphid, diamondback moth) have evolved resistance to multiple chemicals

21. Evolution of pesticide resistance
Over 586 species are resistant to 330 insecticides
Hundreds of weeds and plant diseases have evolved resistance to herbicides and pesticides

22. Biological control (biocontrol)
Biological control: uses a pest’s predators or diseases to control the pest
But organisms can’t be easily controlled
Organisms can harm nontargets
Example: introduced cactus moths eat rare Florida cacti
Biocontrol must be carefully planned and regulated

23. Integrated pest management (IPM)
Techniques to suppress pests include:
* Biocontrol * Habitat alteration
* Chemicals, if necessary * Crop rotation
* Population monitoring * Transgenic crops
* Alternative tillage methods
* Mechanical pest removal
IPM in Indonesia increased rice yields 13% and saved $179 million/yr in phased-out subsidies

24. Pollinators are beneficial “bugs”
Not all insects are pests; some are absolutely vital
Over 800 cultivated plants rely on pollinators
Pollination: male plant sex cells fertilize female sex cells
Flowers are evolutionary adaptations to attract pollinators
Nectar, pollen, sweet smells, bright colors
U.S. bees provide $3 billion/year in pollination services, but parasitic mites decimated populations
Beekeepers were driven to financial ruin

25. Conservation of pollinators is vital
Populations of bees further plummeted in 2006
Colony collapse disorder: entire beehives have died
One-third of all U.S. honeybees die/year
Unknown causes—Insecticides? Parasites? Stress?

26. Genetically modified food
Despite the Green Revolution, relentless population growth demands more innovation to feed us
Scientists alter genes of organisms
Crop plants and livestock
Genetically modified organisms enhance nutrition and agricultural efficiency
But the risks are not well understood, leading to anxiety and protest from:
Consumer advocates, small farmers, environmentalists, critics of big business

27. Genetically modified organisms
Genetic engineering: laboratory manipulation of genetic material
Add, delete, modify DNA
Genetically modified (GM) organisms: organisms that have been genetically engineered using …
Recombinant DNA: DNA created from multiple organisms

28. Biotechnology is impacting our lives
The goal of genetic engineering: put genes that code for desirable traits (rapid growth, nutrition, etc.)
Into organisms lacking those traits
Transgenic organism: an organism that contains DNA from another species
Transgenes: the genes that have moved between organisms
Biotechnology: the application of biological science to create products derived from organisms
It has created medicines, cleaned up pollution, dissolved blood clots, and made better food

29. Some genetically modified foods

30. Selective breeding vs. genetic engineering
Selective breeding: changes organisms through selective breeding of the same or similar species
Works with organisms in the field
Genes come together on their own
Uses the process of selection to change organisms
Genetic engineering: mixes genes of different species (e.g., spiders and goats)
Works with genetic material in the lab
Directly creates novel combinations of genes
Resembles the process of mutation

31. Biotechnology is changing our world
GM foods are a big business
Most GM crops are herbicide and pesticide resistant
Large-scale farmers grow crops more efficiently
Most U.S. corn, soybeans, and cotton are genetically modified

32. What are the impacts of GM crops?
As GM crops expanded, citizens, scientists, and policymakers became concerned that:
GM crops could have adverse impacts on human health
Pests could evolve resistance and become “superpests” and “superweeds”
GM crops could harm nontarget organisms
GM crops could interbreed with closely related wild plants
Millions of Americans eat GM foods without obvious harm
But it is too early to dismiss concerns

33. Some impacts of GM crops
Mixed results on pesticide use
Insecticide use declined, but herbicide use increased
GM foods can advance sustainable agriculture
Grown with no-till farming
Drought resistant and high-yielding
Problems with GM foods:
Expensive
Little incentive to develop crops for small-scale farmers

34. Genetic engineering is profit driven
This “gene revolution” is driven by financial interests of corporations
A few large agribiotech corporations dominate the world’s food supply
Europeans want GM foods labeled
U.S. consumers have mostly accepted GM crops
Brazil, India, and China are aggressively pursuing GM crops
We should follow the precautionary principle and proceed with caution on GM foods

35. Consumption of animal products is growing
As developing nations become wealthier, meat consumption will double by 2050
As wealth and commerce increase, so does consumption of meat, milk, and eggs
Since 1950, global meat production has increased fivefold, and per capita meat consumption has doubled

36. Our food choices are also energy choices
Eating meat is far less energy efficient than eating crops
90% of energy is lost from one trophic level to the next
Some animals convert grain into meat more efficiently than others

37. Resources needed for livestock production
Land and water are needed to raise food for livestock
Eggs and chicken meat require the least
Producing beef requires the most
When we choose what to eat, we choose how we use resources

38. Feedlot agriculture
Feedlots (factory farms): also called concentrated animal feeding operations (CAFOs)
Huge warehouses or pens deliver food to animals living at extremely high densities
House over half of the world’s pork and most of its poultry
Most U.S. meat is raised in feedlots, which use liberal amounts of antibiotics to control disease

39. Pros and cons of feedlot agriculture
It allows greater production of affordable meat
It reduces grazing impacts on the land
45% of the world’s grain is fed to livestock
Endangering food security for the world’s poor
Feedlots produce huge amounts of manure and urine
Can pollute surface water and groundwater
Crowded housing causes outbreaks in disease
Heavy use of antibiotics
More greenhouse gases (CO2, methane, nitrous oxides) than automobile emissions

40. We raise seafood with aquaculture
World wild fish populations are plummeting
Increased demand and technology
Aquaculture: raising aquatic organisms in a controlled environment
Open-water pens or land- based ponds
The fastest-growing type of food production
Most widespread in Asia

41. Aquaculture’s benefits and drawbacks
Reduces pressure on overharvested wild fish
Uses fewer fossil fuels, is safer, and produces more fish than commercial fishing
Drawbacks:
Lots of waste produced
Uses grain, which affects food supplies for people
Fish meal is made from wild ocean fish
Escaped fish introduce disease or outcompete wild fish

42. Organic agriculture
Sustainable agriculture keeps high crop yields, minimizes resource use, and decreases environmental impacts
Organic agriculture: uses no synthetic fertilizers, insecticides, fungicides, or herbicides
Organic Food Production Act (1990) establishes national standards for organic products
The USDA issued criteria in 2000 by which food could be labeled organic
California, Washington, Texas passed stricter guidelines for labeling

43. Benefits and costs of organic farming
Farmers have lower input costs, enhanced income, reduced chemical pollution and soil degradation
Obstacles include the risks and costs of switching to new methods
The main obstacle to consumers is the higher price
But many are willing to pay the price
Worldwide, sales surpassed $54 billion

44. Organic agriculture is booming
U.S. consumers spent $24.8 billion on organic food in 2009
U.S. land devoted to organic agriculture has quadrupled since the mid- 1990s

45. Governments can support organic farming
The U.S Farm Bill gives $112 million over 5 years for organic agriculture
It helps defray certification costs
In 1993, the European Union started supporting farmers financially during conversion to organic farming
Reduced inputs and higher market prices will make it as profitable as conventional methods

46. Locally supported agriculture is growing
Sustainable agriculture reduces fossil fuel use from long-distance transport of products
The average U.S. food product travels 1,400 miles
Farmers’ markets: provide fresh, locally grown food
Provide organic items and unique local varieties
Community-supported agriculture (CSA)
Consumers pay farmers in advance for produce
Consumers get fresh food
Farmers get a guaranteed income

47. Sustainable agriculture: a roadmap for the future
Sustainable agriculture mimics natural ecosystems
They operate in cycles and are internally stabilized by negative feedback loops
Agricultural systems can be integrated with the surrounding ecosystems
Reducing environmental impacts from food production
Making agriculture sustainable is crucial for all of us

48. Biofuels can affect food supplies
Biofuels: fuels derived from organic materials
Replace petroleum in engines
Ethanol: a biofuel derived from corn
The main biofuel in the U.S.
2007 subsidies doubled U.S. production
Use of corn for biofuel reduced corn supplies
Food prices increased
Farmers sold corn for ethanol, not food
Farmers planted biofuels, not food crops
Riots erupted in many nations

49. Conclusion
Industrialized agriculture has had substantial negative environmental consequences
To support 9 billion humans, we must shift to sustainable agriculture to prevent further land degradation
Biological pest control, organic agriculture
Pollinator protection, preservation of native crops
Aquaculture
Careful, responsible genetic modification of food 49

50. Case Studies MEDC- (Dustbowl 1930s) LEDC- India see article