1. Let’s dish some dirt!  Please get out paper for notes.  Please read the board.

2. Dishing the dirt!

3. Soil Resources complex mixture of inorganic minerals (clay, silt, sand), decaying matter, & living organisms. potentially renewable resource; typically 200–1000 years to form 2.5 centimeters (1 inch) of topsoil. © Brooks/Cole Publishing Company / ITP

5. Soil formation  Physical Freeze/thaw cycle Freeze/thaw cycle Weathering/erosion Weathering/erosion  Biological Lichen action Lichen action Decomposition Decomposition

6. The granite rock cracks and breaks off as it is heated and cooled each day and season. This is the first step in the formation of soil.

7. Physical: Freeze/thaw cycle

8. Decomposition: adding carbon, N,P,K during soil formation

10. Soil Food Webs are complex! © Brooks/Cole Publishing Company / ITP soil food webs complex; figure shows simplified soil food web. Fig. 13–15

11. Soil Nutrient Cycling © Brooks/Cole Publishing Company / ITP pathways of nutrients in soils Fig. 5–15

12. Generalized Soil Profile © Brooks/Cole Publishing Company / ITP O horizon: leaf litter A horizon: topsoil B horizon: subsoil C horizon: parent material bedrock

13. Examples of Soil Profiles Fig. 13–17 a & b © Brooks/Cole Publishing Company / ITP

14. More Examples of Soil Profiles Fig. 13–17 c & d © Brooks/Cole Publishing Company / ITP

19. Ecosystem comparison!  Prairies – rich soil (deep, lots of humus, nutrients)  Tropical Rainforests – poor soils! Rapid decomposition increases rate of nutrient uptake!

20. Soil types determined by  Particle size  Chemical composition (bedrock material)  Color  pH

21. Soil texture  Sand  Silt  Clay  Landfills?  Wetlands?

22. Soil Texture © Brooks/Cole Publishing Company / ITP determined by particular mix of clay, silt, & sand Fig. 13–18

23. Erosion movement of soil, especially litter & topsoil, from one place to another makes soil less fertile & less able to hold water; topsoil eroding faster than it forms in about one–third of the world's cropland. © Brooks/Cole Publishing Company / ITP

24. Soil Erosion Fig.13–20 © Brooks/Cole Publishing Company / ITP

25. 1930s Dust Bowl Fig.13–21 © Brooks/Cole Publishing Company / ITP

26. Desertification causes: overgrazing; deforestation & devegetation; surface mining; poor irrigation; salt buildup; farming unsuitable terrain; soil compaction. Fig.13–22 © Brooks/Cole Publishing Company / ITP

27. Problems of Irrigation © Brooks/Cole Publishing Company / ITP Fig.13–23 Salinization: salts build up to levels that decrease yields or prevent cultivation Waterlogging excess irrigation water raises water table & lowers crop productivity

28. Soil Conservation reduces soil erosion & restores fertility some methods: conservation–tillage terracing, contour farming, strip cropping, alley cropping organic fertilizers crop rotation © Brooks/Cole Publishing Company / ITP

29. Conservation-Tillage Farming minimizes soil disturbance uses special tillers or no–till methods that inject seeds, fertilizers, & herbicides in unplowed soil poses new problems of heavy herbicide use © Brooks/Cole Publishing Company / ITP

30. Some Means to Prevent Erosion terracing protects steep slopes contour farming follows natural land contours strip cropping maintains strips of different vegetation between crops alley cropping grows crops between rows of trees © Brooks/Cole Publishing Company / ITP

31. organic fertilizers: manure, "green manure" = plant matter, & compost decreased use of inorganic fertilizers crop rotation: alternating between different crops & fallow times; planting crops that restore nutrients Some Means to Prevent Soil Degradation © Brooks/Cole Publishing Company / ITP

32. Pesticides – “To use or not to use?”

33. What you already know about pesticides....  The case FOR pesticides  The case AGAINST pesticides

34. A spectrum of choices Conventional Integrated PestOrganic Biodynamic Agriculturemanagementfarming agriculture Least sustainablemost sustainable

35. Integrated pest management  Overarching philosophy: Eradication of pests is not possible, so the goal must be pest suppression. Eradication of pests is not possible, so the goal must be pest suppression. General practice: Monitor pest populations. When damage of crops will cost more than the cost of action, IPM managers take steps to control pests. Pesticides will be used only as a last resort. General practice: Monitor pest populations. When damage of crops will cost more than the cost of action, IPM managers take steps to control pests. Pesticides will be used only as a last resort.

37. Cultivation/physical approaches  Crop rotation –  non-legume, legume, fallow field/cover crop

38. Cultivation/physical approaches Hedge rows provide shelter for beneficial insects, birds and other pest predators

39. Cultivation Approaches  Delayed planting If the pest can’t find the crop at the right part of it’s life cycle, the pest can’t use the crop.

40. Cultivation Approaches  Polyculture, intercropping and agroforestry – increasing diversity of crops!

41. Biological pest control Release beneficial insects (pest predators), encourage insectivorous birds

42. Other predators

45. Biological Pest control  Release of sterile males: mate with females, no offspring produced.

46. Chemical Pest control  Pheromones: used in bait traps to lure insects away from crops

47. Chemical control  Hormone disruptors prevent molting or development to next stage.

48. Chemical control  As a last resort, IPM farmers will use pesticides (herbicides, insecticides, rodenticides, fungicides)

49. IPM approaches  Advantages  Disadvantages