1. Chapter 12 Soil and Agriculture
Mr. Manskopf
Class Web Site

2. Essential Questions Covered
What are the components of the soil?
How is soil formed?
What are some of the effects of soil erosion on the land?
Describe the impact of human activities on the land.
How do recycling and composting programs affect the soil?
What impact do pesticides have on the soil?
What affect do fertilizers have on the nitrogen cycle?

3. Who Cares About DIRT?

4. How is my food choice impacting the environment?

5. How come not everyone has enough food?

6. About 38% of Earth’s land surface is used for agriculture.

7. Section 1 Soil Explain how soil is formed.
Describe the different layers (horizons) of soil.
List four characteristics used to classify soil.

8. What is soil made of?
Soil is made up of minerals, organic matter, air, and water.
Soil composition is influenced by climate, organisms, landforms, parent material, and time

9. Soil Composition
Soil is a thin layer over most land that is a complex mix of rock, nutrients, decaying matter, water, air and billions of organisms…many microscopic decomposers

10. Why is soil important Renewable resource…SLOW
Depends upon climate (1cm in 15yrs.)
Basis of life
Filters water
Water storage
Habitat

11. Simplified Soil Food Web

12. Soil Formation
Weathering: Physical and chemical breaking of rocks and minerals into smaller pieces
Erosion and deposition: Pick-up, transport, and drop-off of material from one place to another
Decomposition: Breakdown of waste, organisms, and organic material into simple molecules

13. Weathering of PARENT MATERIAL (ROCK)

14. Decomposition

15. Leaf Litter

16. Different Biomes = Different Parent Material, Climate, Organic Matter = Different Soil

17. Soil Horizons Soil horizons are distinct layers of soil.
A cross-section of soil horizons is a soil profile.
“A” Most Critical

18. Did You Know? In general, organic matter is concentrated in the O and A horizons, making them the most critical for agriculture.

19. Is All DIRT The Same?

20. Soil Characteristics
Soil groups are further classified according to properties such as color, structure, pH, and texture.
Soil texture is based on particle size.

22. Topsoil Color a Great Quick Indicator
Dark, loamy, neutral pH are some of best soils for farming
Dark color often means lots of decayed material (nutrients)

24. Section 1 Review Explain how soil is formed.
Describe the different layers (horizons) of soil.
List four characteristics used to classify soil.

25. Section 1 Quiz
1) After a catastrophe, soil formation is the first step in
A. primary succession.
B. secondary succession.
C. a climax community.

26. 2) Most of the nutrients in soil come from A. chemical weathering. B
2) Most of the nutrients in soil come from A. chemical weathering B. mechanical weathering C. erosion D. decomposition.

27. 3) A farmer interested in raising healthy crops should look for a A
3) A farmer interested in raising healthy crops should look for a A. heavy clay soil with a high pH and a dark color B. loamy soil with a low pH and a light color. C. loamy, clumpy soil with a neutral pH and a dark color D. sandy soil with a high pH, no clumps, and a light color.

28. 4) An example of a soil parent material is A. humus. B. volcanic rock
4) An example of a soil parent material is A. humus B. volcanic rock C. leaf litter D. topsoil.

29. 5) As a farmer, you would be most concerned with the quality of the soil in the A. O horizon B. A horizon C. E horizon D. R horizon.

30. 6) A rancher interested in the quality of the soil in her pasture might use which aspect of soil as a quick indicator of the pasture’s overall fertility? A. color B. smell C. structure D. pH E. Taste

31. 7) Short Answer: If you were to travel to the desert in Arizona, you might find Horizon Layer O and A missing. Why?

32. 8) Short Answer: What determines how quickly Horizon O and A form?

33. Some estimates predict that 50 million people could be displaced in the next 10 years due to desertification, a form of soil degradation.

34. Section 2 Soil Degradation and Conservation
What causes soil erosion?
How serious of a problem is it?
What are ways that farmers, ranchers and forestry lead to soil erosion?

36. Causes of Soil Erosion
Wind
Water #1
People

37. Soil Erosion
Often occurs faster than soil is formed, depleting fertile topsoil
Crops, trees, and other plant communities protect soil from erosion.

38. Did You Know? More than 19 billion hectares (47 billion acres) of the world’s croplands suffer from erosion and other forms of soil degradation resulting from human activities.

39. Impacts of Soil Erosion
Loss of soil fertility
Sediment runoff causes problems in surface water (pollution, clog ditches, boat channels, reservoirs)
#1 source of U.S. water pollution
Renewable only on LONG timeframes (200-1,000yrs. for 1 inch)

40. What time of year do you think most farm fields in U. S
What time of year do you think most farm fields in U.S. are vulnerable to erosion?

41. On Ag. land in U.S. today, soil is eroding 16 times faster than it is created

42. Areas of serious concern Stable or nonvegetative areas
Areas of some concern
Stable or nonvegetative areas

43. Farming Practices That Reduce Erosion
Intercropping: Different crops mixed together
Crop rotation: Crops are alternated.
Shelterbelts: Tall plants block wind.
Conservation tillage: Soil turnover is reduced.
Terracing: Steep slopes turned into “steps”

44. Tillage vs. Conservation Tillage

45. Contour and Strip Cropping

46. Ranching Practices Ranching is the raising and grazing of livestock.
Overgrazing causes and worsens many soil problems.
Range managers encourage grazing limits and enforce them on publicly owned land.

48. Forestry Practices
Forestry practices, such as clear-cutting, can increase erosion.
Today, practices that reduce soil erosion, such as selective logging, are increasingly common.

49. Soil Pollution
Too much, or carelessly timed irrigation can waterlog crops and lead to salinization—a buildup of salts in upper soil horizons.
Toxic pesticides can remain in soil for a long time, eventually filtering to groundwater.
Evaporation
Transpiration
Waterlogging
Less permeable
clay layer

50. Desertification

52. Soil Salinization

54. Soil Pollution

55. Section 2 Review
What causes soil erosion?
How serious of a problem is it?
What are ways that farmers, ranchers and forestry lead to soil erosion?

56. Humans have been practicing agriculture for about 10,000 years.

57. What is that?

58. Aldo Leopold
There are two spiritual dangers in not owning a farm. One is the danger of supposing that breakfast comes from the grocery store, and the other that heat from the furnace.

59. Section 3 Agriculture Describe the history of farming.
Analyze the costs and benefits of the “Green Revolution”
What are some ways farmers control weeds and pests?
Why are pollinators important to farmers?

60. The Beginnings of Agriculture
People were hunter-gatherers through most of human history, until agriculture developed about 10,000 years ago.

61. Why 10,000 years ago?

62. Agriculture History
In early agriculture, people began planting seeds from plants they liked most
Agriculture and livestock provided a stable food supply, which allowed the development of modern civilization.

63. Types of Agriculture
Traditional Agriculture
Industrial Agriculture

64. The Green Revolution
Introduced new technology, crop varieties, and farming practices to the developing world in the mid- to late 1900s
Benefits:
Increased crop yields and saved millions of people from starvation in India and Pakistan
Prevented some deforestation and habitat loss by increasing yields on cultivated land

65. Green Revolution Costs:
Led to a 7000% increase in energy used by agriculture
Worsened erosion, salinization, desertification, eutrophication, and pollution

66. Pests and Weed Control (Farmers Enemies)
Chemical pesticides: Effective and cheap, but can lead to resistance

68. Pests and Weed Control
Biological pest control: Permanent solution, but can harm nontarget organisms
Integrated pest management: Increasingly popular solution, combines chemical and biological pest-control methods
Cactus moth larvae are used to control prickly pear cactus, but also threaten many rare, native cacti around the world.

69. Pollinators Agriculture relies on pollinators, such as insects.
Native and domesticated pollinator populations have declined due to pesticide use, parasites, and other as-of-yet unknown causes

70. Section 3 Review Describe the history of farming.
Analyze the costs and benefits of the “Green Revolution”
What are some ways farmers control weeds and pests?
Why are pollinators important to farmers?