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Soils, agriculture, and the future of food

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Presentation on theme: "Soils, agriculture, and the future of food"— Presentation transcript:

1 Soils, agriculture, and the future of food
6 Soils, agriculture, and the future of food

2 Central Case: No-Till Agriculture in Brazil
Southern Brazil’s farmers were suffering falling yields, erosion, and pollution from agrichemicals. They turned to no-till farming, which bypasses plowing. Erosion was reduced, soils were enhanced, and yields rose greatly. No-till methods are spreading worldwide.

3 Agriculture today We have converted 38% of Earth’s surface for agriculture, the practice of cultivating soil, producing crops, and raising livestock for human use and consumption. Croplands (for growing plant crops) and rangelands (for grazing animal livestock) depend on healthy soil.

4 World soil conditions Soils are becoming degraded in many regions.
Figure 8.1a

5 Soil degradation by continent
Europe’s land is most degraded because of its long history of intensive agriculture. But Asia’s and Africa’s soils are fast becoming degraded. Figure 8.1b

6 Causes of soil degradation
Most soil degradation is caused by: • livestock overgrazing • deforestation • cropland agriculture. Figure 8.2

7 Global food production
World agricultural production has risen faster than human population. Figure 9.1

8 The green revolution An intensification of industrialization of agriculture, which has produced large yield increases since 1950 Increased yield per unit of land farmed Begun in U.S. and other developed nations; exported to developing nations like India and those in Africa are more productive for plant life.

9 Wheat monoculture in Washington
Monocultures Intensified agriculture meant monocultures, vast spreads of a single crop. This is economically efficient, but increases risk of catastrophic failure (“all eggs in one basket”). Wheat monoculture in Washington Figure 9.4a

10 Crop diversity Monocultures also have reduced crop diversity.
90% of all human food now comes from only 15 crop species and 8 livestock species.

11 The green revolution Techniques to increase crop output per unit area of cultivated land (since world was running out of arable land) Technology transfer to developed world in 1940s-80s: Norman Borlaug began in Mexico, then India. Special crop breeds (drought-tolerant, salt-tolerant, etc.) are a key component. It enabled food production to keep pace with population.

12 Green revolution: Environmental impacts
Intensification of agriculture causes environmental harm: • Pollution from synthetic fertilizers • Pollution from synthetic pesticides • Water depleted for irrigation • Fossil fuels used for heavy equipment However, without the green revolution, much more land would have been converted for agriculture, destroying forests, wetlands, and other ecosystems.

13 Feeding the world In 1983, the amount of grain produced per capita leveled off and began to decline. Figure 8.3

14 Pest management Terms pest and weed have no scientific or objective definitions. Any organism that does something we humans don’t like gets called a pest or a weed. The organisms are simply trying to survive and reproduce… and a monoculture is an irresistible smorgasbord of food for them.

15 Chemical pesticides Synthetic poisons that target organisms judged to be pests

16 Inorganic Commercial Fertilizers
Trade-Offs Inorganic Commercial Fertilizers Advantages Disadvantages Easy to transport Easy to store Easy to apply Inexpensive to produce Help feed one of every three people in the world Without commercial inorganic fertilizers, world food output could drop by 40% Do not add humus to soil Reduce organic matter in soil Reduce ability of soil to hold water Lower oxygen content of soil Require large amounts of energy to produce, transport, and apply Release the greenhouse gas nitrous oxide (N2O) Runoff can overfertilize nearby lakes and kill fish Figure Page 286


18 Pesticide use Pesticide use is still rising sharply across the world, although growth has slowed in the U.S. 1 billion kg (2 billion lbs.) of pesticides are applied each year in the U.S. Figure 9.5

19 Pests evolve resistance to pesticides
Pesticides gradually become less effective, because pests evolve resistance to them. Those few pests that survive pesticide applications because they happen to be genetically immune will be the ones that reproduce and pass on their genes to the next generation. This is evolution by natural selection, and it threatens our very food supply.

20 Pests evolve resistance to pesticides
1. Pests attack crop 2. Pesticide applied Figure 9.6

21 Pests evolve resistance to pesticides
3. All pests except a few with innate resistance are killed 4. Survivors breed and produce pesticide-resistant population Figure 9.6

22 Pests evolve resistance to pesticides
5. Pesticide applied again 6. Has little effect. More-toxic chemicals must be developed. Figure 9.6

23 Biological control Synthetic chemicals can pollute and be health hazards. Biological control (biocontrol) avoids this. Biocontol entails battling pests and weeds with other organisms that are natural enemies of those pests and weeds. (“The enemy of my enemy is my friend.”)

24 Figure 23-7 Page 528

25 Biological control Biocontrol has had success stories.
Bacillus thuringiensis (Bt) = soil bacterium that kills many insects. In many cases, seemingly safe and effective. Cactus moth, Cactoblastis cactorum (above), was used to wipe out invasive prickly pear cactus in Australia. Figure 9.7

26 But biocontrol is risky
Most biocontrol agents are introduced from elsewhere. Some may turn invasive and become pests themselves! Cactus moths brought to the Caribbean jumped to Florida, are eating native cacti, and spreading. Wasps and flies brought to Hawaii to control crop pests are parasitizing native caterpillars in wilderness areas.

27 Integrated pest management (IPM)
Combines biocontrol, chemical, and other methods May involve: • Biocontrol • Pesticides • Close population monitoring • Habitat modification • Crop rotation • Transgenic crops • Alternative tillage • Mechanical pest removal

28 Genetic modification of food
Manipulating and engineering genetic material in the lab may represent the best hope for increasing agricultural production further without destroying more natural lands. But many people remain uneasy about genetically engineering crop plants and other organisms.

29 Genetic engineering uses recombinant DNA
Genetic engineering (GE) = directly manipulating an organism’s genetic material in the lab by adding, deleting, or changing segments of its DNA Genetically modified (GM) organisms = genetically engineered using recombinant DNA technology Recombinant DNA = DNA patched together from DNA of multiple organisms (e.g., adding disease-resistance genes from one plant to the genes of another)

30 Transgenes and biotechnology
Genes moved between organisms are transgenes, and the organisms are transgenic. These efforts are one type of biotechnology, the material application of biological science to create products derived from organisms.

31 Genetic engineering vs. traditional breeding
They are different: GE can mix genes of very different species. GE is in vitro lab work, not with whole organisms. GE uses novel gene combinations that didn’t come together on their own. They are similar: We have been altering crop genes (by artificial selection) for thousands of years. There is no fundamental difference: both approaches modify organisms genetically.

32 Some GM foods Golden rice: Enriched with vitamin A. But too much hype?
FlavrSavr tomato: Better taste? But pulled from market. Ice-minus strawberries: Frost-resistant bacteria sprayed on. Images alarmed public. Bt crops: Widely used on U.S. crops. But ecological concerns? Figure 9.12

33 Some GM foods Bt sunflowers: Insect resistant.
But could hybridize with wild relatives to create “superweeds”? StarLink corn: Bt corn variety. Genes spread to non-GM corn; pulled from market. Roundup-Ready crops: Resistant to Monsanto’s herbicide. But encourages more herbicide use? Terminator seeds: Plants kill their own seeds. Farmers forced to buy seeds each year. Figure 9.12

34 Prevalence of GM foods Although many early GM crops ran into bad publicity or other problems, biotechnology is already transforming the U.S. food supply. Two-thirds of U.S. soybeans, corn, and cotton are now genetically modified strains.

35 Prevalence of GM foods Nearly 6 million farmers in 16 nations plant GM crops. But most are grown by 4 nations. The U.S. grows 66% of the world’s GM crops. number of plantings have grown >10%/year Figure 9.13

36 Genetically Modified Food and Crops
Trade-Offs Genetically Modified Food and Crops Projected Advantages Projected Disadvantages Need less fertilizer Need less water More resistant to insects, plant disease, frost, and drought Faster growth Can grow in slightly salty soils Less spoilage Better flavor Less use of conventional pesticides Tolerate higher levels of pesticide use Higher yields Irreversible and unpredictable genetic and ecological effects Harmful toxins in food From possible plant cell Mutations New allergens in food Lower nutrition Increased evolution of Pesticide-resistant Insects and plant disease Creation of herbicide- Resistant weeds Harm beneficial insects Lower genetic diversity

37 Scientific concerns about GM organisms
Are there health risks for people? Can transgenes escape into wild plants, pollute ecosystems, harm organisms? Can pests evolve resistance to GM crops just as they can to pesticides? Can transgenes jump from crops to weeds and make them into “superweeds”? Can transgenes get into traditional native crop races and ruin their integrity?

38 Europe vs. America Europe: has followed precautionary principle in approach to GM foods. Governments have listened to popular opposition among their citizens. U.S.: GM foods were introduced and accepted with relatively little public debate. Relations over agricultural trade have been uneasy, and it remains to be seen whether Europe will accept more GM foods from the U.S.

39 Viewpoints: Genetically modified foods
Indra Vasil Ignacio Chapela “Biotech crops are already helping to conserve valuable natural resources, reduce the use of harmful agro-chemicals, produce more nutritious foods, and promote economic development.” “We should expect fundamental alterations in ecosystems with the release of transgenic crops… We are experiencing a global experiment without controls.” From Viewpoints

40 Preserving crop diversity
Native cultivars of crops are important to preserve, in case we need their genes to overcome future pests or pathogens. Diversity of cultivars has been rapidly disappearing from all crops throughout the world.

41 Seed banks preserve seeds, crop varieties
Seed banks are living museums of crop diversity, saving collections of seeds and growing them into plants every few years to renew the collection. Careful hand pollination helps ensure plants of one type do not interbreed with plants of another. Figure 9.14

42 Sustainable agriculture
Agriculture that can practiced the same way far into the future Does not deplete soils faster than they form Does not reduce healthy soil, clean water, and genetic diversity essential for long-term crop and livestock production Low-input agriculture = small amounts of pesticides, fertilizers, water, growth hormones, fossil fuel energy, etc. Organic agriculture = no synthetic chemicals used. Instead, biocontrol, composting, etc.

43 Organic farming Small percent of market, but is growing fast
1% of U.S. market, but growing 20%/yr 3–5% of European market, but growing 30%/yr Organic produce: Advantages for consumers: healthier; environmentally better Disadvantages for consumers: less uniform and appealing-looking; more expensive

44 Conclusions: Solutions
Biocontrol and IPM offer alternatives to pesticides. Further research and experience with GM crops may eventually resolve questions about impacts, and allow us to maximize benefits while minimizing harm. More funding for seed banks can rebuild crop diversity. Ways are being developed to make feedlot agriculture and aquaculture safer and cleaner.

45 Conclusions: Solutions
Organic farming is popular and growing fast. Green revolution advances have kept up with food demand so far. Improved distribution and slowed population growth would help further. Farming strategies like no-till farming, contour farming, terracing, etc., help control erosion. Government laws, and government extension agents working with farmers, have helped improve farming practices and control soil degradation. Better grazing and logging practices exist that have far less impact on soils.

46 Industrialized agriculture
Modern intensive agriculture on a large scale: • Crop monocultures • Synthetic chemical herbicides, pesticides • Extensive mechanization • Fossil fuel use

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