Lesson 9: Agriculture and Environment

1. Lesson 9: Agriculture and Environment Big Question: Can We Feed the World Without Destroying the Environment?

2. Some Facts about Agriculture Agriculture may be the most sustainable human activity. How much do we actually consume each year? In America, we consume more than half a ton of food a year per person. Farmers feed the more than 6 billion people in the world (see the U.S. Census Bureau's Population Clock for the current world population.

3. Most of the world’s food is provided by only 14 plant species. What Do We All Eat?

4. Where the World’s Major Crops Grow

5. The Bad News About Farming • Farming often degrades soil. • Fertilizers and pesticides affect soil, water, and downstream ecosystems. • Irrigation of farmland can lead to salinization (the buildup of salts in the soil to the point that crops can no longer grow). • Irrigation can also cause an accumulation of toxic metals. • Farming can cause a loss of biodiversity.

6. Population Growth and Food Production Another big problem: if the human population doubles as expected, agricultural production will need to double. Where would we produce all that additional food?

7. Dust Bowls and Our Eroding Soils “The Worst Hard Time” http://www.amazon.com/Worst-Hard-Time-Survived-American/dp/061834697X; The Plow that Broke the Plains http://www.archive.org/details/PlowThatBrokethePlains1

8. Soil Conservation Practices Reduce Erosion "Soil Erosion in the Palouse River Basin: Indications of Improvement" at http://wa.water.usgs.gov/pubs/fs/fs069-98/

9. The Plow Puzzle

10. In areas with a long history of plowing, farmers kept farming by putting nutrients back into the soil. They used organic fertilizers, such as animal manure. Chemical fertilizers were an important development to increase crop production in the twentieth century. Long-term Sustainable Agriculture

11. Where Eroded Soil Goes Much of it travels down streams and rivers. 2.7 billion metric tons per year are deposited in reservoirs, rivers, and lakes. Soil eroded from farms carries chemicals that affect the environment. Fertilizers carried by sediments increase the growth of aquatic algae: eutrophication. Sediment damage costs the United States about $500 million a year. "The Washington and Oregon Mid-Shelf Silt Deposit and Its Relation to the late Holocene Colombia River Sediment Budget" at http://wrgis.wr.usgs.gov/open-file/of99-173/

12. Making Soils Sustainable In ideal farming, the amount of soil lost would never be greater than the amount of new soil produce. In contour plowing, the land is plowed as horizontally as possible across the slopes.Contour plowing greatly reduces soil erosion, and uses less fuel and time.

13. Contour Plowing and No-till Agriculture Mentioned link at http://www.ars.usda.gov/research/publications/publications.htm?seq_no_115=216627

14. Conservation Tillage In the United States

15. Farm Pests

16. How Much Pesticide Do We Release into the Environment? And Where Does It Go? About 500 million kilograms of 600 different pesticides were used in the United States in 2005. About 60% of pesticides found in U.S. waters are herbicides (weed killers). Surprisingly little is known about past and present concentrations of pesticides in major rivers. We need a wide-scale program to monitor pesticides in our water.

17. The Search for a Magic Bullet To limit pests, many farmers used slash-and-burn agriculture, where farmers partially cleared small patches of vegetation in a forest.

18. DDT Bald eagle at Union Bay Natural Area (UW campus) Mt. Rainier in background from www.flickr.com

19. Ecological Approaches to Pest Control Research to control agriculture pests has shifted to a fourth stage, biological control, and a fifth stage, integrated pest management. Biological control uses predators and parasites to control pests. An effective biological control agents is Bacillus thuringiensis (BT). It causes a disease that affects caterpillars and the larvae of other insect pests. Biological control is safe and effective.

20. Integrated Pest Management (IPM) Biological control has not solved all problems. IPM uses biological control, certain chemical pesticides, surveys, and careful attention to the timing of planting and pesticide use.

21. Hybrids and GeneticModification: Creating Better Crops Genetic modification is a different approach to pest management. People used to think that corn that looked good—a nicely shaped ear of corn with straight rows of kernels—was the most productive. Henry Wallace’s experiment showed that looks had nothing to do with productivity.

22. Hybrids and the Green Revolution Led to the scientific development of hybrid corn. Hybridization was so successful that it led to the Green Revolution: development of new strains of maize, wheat, and rice with greater disease resistance and ability to grow under poor conditions.

23. Biotech Acreage planted with genetically modified crops (GMCs) has grown rapidly since 1996.

24. Bioteching New Hybrids The development of hybrids within a species is a natural phenomenon. However, there are concerns about superhybrids and superweeds: • Superhybrids may require more water and fertilizer. • Superweeds may be difficult to control. There are also concerns about potential effects of growing GMCs on marginal lands.

25. Grazing on Rangelands: An Environmental Benefit or Problem? Almost half of Earth’s land area is used as rangeland. Much of it is arid and is in poor condition from overgrazing.

26. Overgrazing Land near streams fares the worst. Retracing the steps of Lewis and Clark reveals the damage done since their 1804 expedition.

27. Organic Farming

28. Deserts: What Are They andWhat Causes Them?

29. Does Farming Change the Biosphere?

30. Lesson 9: Agriculture and Environment Questions? E-mail your TA. eschelp@u.washington.edu