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Soil and Food. Soil: What is it? 1.Inorganic materials (clay, silt, and sand) weathered from solid rock 2.Living organisms (worms, insects, mites, fungi,

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Presentation on theme: "Soil and Food. Soil: What is it? 1.Inorganic materials (clay, silt, and sand) weathered from solid rock 2.Living organisms (worms, insects, mites, fungi,"— Presentation transcript:

1 Soil and Food

2 Soil: What is it? 1.Inorganic materials (clay, silt, and sand) weathered from solid rock 2.Living organisms (worms, insects, mites, fungi, …) 3.Decaying organic matter 4.Water 5.air

3 Soil Who cares?

4 Soil Who cares? –Critical to driving biogeochemical cycles –HNOPS in CHNOPS comes from the soil; YOU come from the soil! C 1480 H 2960 N 16 O 1480 P 1.8 S AirSoil

5 How long does it take for soil to form?

6 Soil How long does it take for soil to form? –200-1,000 years for 1 inch of soil

7 Soil What influences soil properties?

8 Soil Profile Dig into the soil and you see the soil’s profile: all the different layers (called horizons) of soil, from the surface litter to the bedrock

9 Soil Horizons Topsoil Zone of Leaching Subsoil Parent Material Bedrock Surface Litter

10 Surface Litter and Topsoil

11 Soil Surface litter: fresh and partly decomposed organic matter Topsoil: where most living things and nutrients are Zone of leaching: where dissolved materials from above move down Subsoil: accumulated materials from above Parent material: partially broken down rock; source of minerals and inorganic matter in soil Bedrock: underlying, unweathered rock

12 Not all soils have the same profile

13 Let’s look at tropical soils

14 Tropical rainforest soil Have a shallow topsoil layer because of rapid decomposition Lots of rainfall removes a lot of the silica from the topsoil, but leaves behind metals like aluminum and iron. If you remove the plants, the topsoil washes away

15 Tropical rainforest soil Leaving behind the metal-rich subsoil, which hardens in the sunlight, eventually turning into a hard, red soil/dirt that doesn’t absorb water and can’t support plants Can grow crops there for 3 yrs or so Then switch to cattle for another 3-5 yrs And then land is abandoned

16 Tropical rainforest soil So, what is the take-home message? –Where we grow crops is not just determined by climate; soil type must be considered.

17 Types of soil profiles: Soils have been cataloged all over the U.S. and most of the world, at this point in time. See next two slides…

18 U.S. Soil Map

19 Soil Profile and Information for the Tucson Area

20 Human impacts on soils Soil erosion: movement of soil components (esp. topsoil) from one place to another

21 Types of soil erosion Figure 8.11 Splash erosion Rill erosion Gully erosion Sheet erosion

22 Human impacts on soils How is soil moved? –1. Wind –2. Moving water

23 Human impacts on soils What are the rates of soil erosion? –In U.S., for 1/3 of all cropland, erosion rates exceed replacement rates for soil –Amount of topsoil lost in the U.S. each year would fill a dumptruck 3,500 miles long

24 Human impacts on soils Where does the soil go? –Oceans –Somewhere else … where it’s not useful as soil anymore...

25 Human impacts on soils What factor makes the land more susceptible to erosion? –VEGETATION REMOVAL Why? –1. Vegetation (roots) hold the soil in place –2. Plants slow down wind and running water (less energy)

26 Human impacts on soils: erosion TypeTons soil eroded% rain that runs off Bare soil41 tons/hectare30%

27 Human impacts on soils: erosion TypeTons soil eroded% rain that runs off Bare soil41 tons/hectare30% Continuous corn19.7 tons/hectare29%

28 Human impacts on soils: erosion TypeTons soil eroded% rain that runs off Bare soil41 tons/hectare30% Continuous corn19.7 tons/hectare29% Continuous wheat 10.1 tons/hectare23%

29 Human impacts on soils: erosion TypeTons soil eroded% rain that runs off Bare soil41 tons/hectare30% Continuous corn19.7 tons/hectare29% Continuous wheat 10.1 tons/hectare23% Rotate corn, wheat, clover2.7 tons/hectare14%

30 Human impacts on soils: erosion TypeTons soil eroded% rain that runs off Bare soil41 tons/hectare30% Continuous corn19.7 tons/hectare29% Continuous wheat 10.1 tons/hectare23% Rotate corn, wheat, clover2.7 tons/hectare14% Continuous bluegrass0.3 tons/hectare12% –Based on 14 years of data from the Missouri Experiment Station, Columbia, Missouri

31 Human impacts on soils: erosion So, what was the take-message of that last table?

32 Human impacts on soils: erosion So, what was the take-message of that last table? –Amount and type of vegetation affects the amount of erosion of soil that occurs

33 Human impacts on soils: erosion What activities lead to soil erosion?

34 Effects of Soil Erosion –1. Loss of productivity of the land Less soil, less nutrients, less water-holding capacity …. Less growth

35 Effects of Soil Erosion –2. Increased air and water pollution From dust in the air and soil in the water...

36 Effects of Soil Erosion –3. Increased flooding: due to less water holding capacity of the soil

37 Effects of Soil Erosion –4. Increased gullying: thus loss of productive land.

38 Effects of Soil Erosion –5. Increased costs due to buying fertilizer, irrigation, etc.

39 Effects of Soil Erosion –6. More irrigation leads to salinization of soils and eventually waterlogging (as a farmer attempts to flush out the salts…)

40 Human impacts on soils: conservation 1930s dust bowl was a wake-up call (in U.S.) 1935 Soil Conservation Act established Soil Conservation Service: maintains soils in the U.S. using education, laws, incentives, disincentives...

41 Soil Conservation Methods

42 Food United States: The Revis family of North Carolina Food expenditure for one week: $ Chad: The Aboubakar family of Breidjing Camp Food expenditure for one week: $1.23 From the book, "Hungry Planet"

43 Food Malthus, 1700s: –Population is increasing exponentially –Food resources are increasing linearly –………… BIG problem!

44 Food –Malthus didn’t/couldn’t anticipate the industrial and green revolutions, which have allowed food resources to increase exponentially for the last few 100 y

45 Food BUT Is this maxed out?

46

47 Per capita food production is leveling off world wide

48 Food: Grain harvests –World grain production has been increasing thru time –But production per person has leveled off, area under production has leveled off, and the grain harvested area per person has decreased

49 Food So, do you think we will be able to supply enough food for everyone in the future? Depends on –Rate of population growth –Ability to increase food availability

50 Food Let’s talk about our food for a minute. What do we eat? –2 main crops make up 60% of our calories –2 other crops make up most of the rest ?

51 Food Let’s talk about our food for a minute. What do we eat? –4 main crops 1. Wheat 2. Rice 3. Corn 4. Potatoes

52 Food What do we eat? –4 main crops 1. Wheat3. Corn 2. Rice4. Potatoes Problems? –1. These are all annuals that require yearly planting and soil disturbance...

53 Food Problems? –1. These are all annuals that require yearly planting and soil disturbance... –2. Having just a few big producers Reduces genetic variability Which reduces chances of adapting if there is a change (disease, climate change….) Solutions?

54 Food We need to diversify our food sources: more strains, more types of food

55 Food What do we eat? –8 non-fish domesticated livestock types provide the bulk of our non-plant diet. What are they?

56 Food What do we eat? –8 non-fish domesticated livestock types provide the bulk of our non-plant diet. What are they? Pig, goat, sheep, cow, duck, turkey, chicken, rabbit

57 Food How do we make more food available to the world market? –1. Put new land into production –2. Increase yields –3. Improve use of existing food supply

58 Food How do we make more food available to the world market? –1. Put new land into production The land that isn’t in production right now is not in production for a reason! So, there really isn’t that much new land for food production. Plus, land is being urbanized and we are losing agricultural land...

59 Food How do we make more food available to the world market? –2. Increase yields Industrial and green revolution: farm machinery, pesticides, fertilizer, irrigation, higher yielding crop varieties. All of this has increased yields over the past 150 y, but we are maxing out on pesticides, fertilizer, irrigation.

60 Food How do we make more food available to the world market? –3. Improve use of existing food supply A) feed lower on the food chain –90% of all U.S. grain is fed to livestock

61 Food How do we make more food available to the world market? –3. Improve use of existing food supply B) develop better food preservation techniques –Losses up to 30%

62 Food How do we make more food available to the world market? –3. Improve use of existing food supply C) better food distribution –Drought and/or civil war areas: loss of infrastructure, diversion of “man” power from fields...

63 Food How do we make more food available to the world market? –3. Improve use of existing food supply feed lower on the food chain develop better food preservation techniques better food distribution education: Improve nutrition

64 Food Integrated Pest Management: yet another thing that could help

65 Food Integrated Pest Management: using a combination of approaches to reduce pests, improve yields

66 Food Integrated Pest Management Approaches: –1. Modify cultivation procedure: crop rotation, multi-cropping,...

67 Food Integrated Pest Management Approaches: –1. Modify cultivation procedure –2. Artificial selection and genetic engineering

68 Food Integrated Pest Management Approaches: –1. Modify cultivation procedure –2. Artificial selection and genetic engineering –3. Biological control of pests

69 Food Integrated Pest Management Approaches: –1. Modify cultivation procedure –2. Artificial selection and genetic engineering –3. Biological control of pests –4. Insect traps and sterilization

70 Food Integrated Pest Management Approaches: –1. Modify cultivation procedure –2. Artificial selection and genetic engineering –3. Biological control of pests –4. Insect traps and sterilization –5. Chemical use only as a last resort

71 Food Integrated Pest Management Approaches: –1. Modify cultivation procedure –2. Artificial selection and genetic engineering –3. Biological control of pests –4. Insect traps and sterilization –5. Chemical use only as a last resort –6. Change consumer attitude: blemishes, etc.


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