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Compost to the Rescue -- 3 reasons to fix the soil and save the planet

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Want to store more carbon? Fix the soil. Reduce runoff and degrade pollutants? Fix the soil. How to fix the soil? Use compost.

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Compost to the Rescue -- 3 reasons to fix the soil and save the planet

  1. 1. Compost to the Rescue 3 reasons to fix the soil and save the planet
  2. 2. Our planet is facing some major health issues.
  3. 3. Industrial farming and other human activities have led to historic loss of topsoil and carbon storage capacity.
  4. 4. Carbon dioxide (CO2) build-up in the atmosphere is driving climate change.
  5. 5. Pollutants contaminate air, soil, and water.
  6. 6. But there is one simple action everyone can choose to help resolve these issues.
  7. 7. By composting organic waste and using that compost as a soil amendment, humans can undo much of that damage.
  8. 8. 1. Compost’s impact on soil and carbon storage
  9. 9. Compost rebuilds the topsoil layer by replenishing organic matter and soil microbes lost to human activities.
  10. 10. Adding to the topsoil layer also increases carbon storage capacity.
  11. 11. Compost “feeds” soils at the surface and contributes carbon for long- or short-term sequestration.
  12. 12. How does it work?
  13. 13. A typical compost is 50%-60% carbon.
  14. 14. This carbon can be stored in upper soil layers or carried several meters deep into the soil by earthworms and other transport mechanisms.
  15. 15. As soil improves, so do plants. More carbon- rich biomass above and below the surface further increases carbon availability to soil.
  16. 16. As long as the soil remains undisturbed, that carbon can be stored indefinitely.
  17. 17. Every pound of additional carbon sequestered in the soil represents 3.67 pounds of carbon dioxide removed from the atmosphere.
  18. 18. How much will it take?
  19. 19. One scientist suggests the capture of 100 percent of current CO2 emissions would require a land area about twice the size of Egypt, using plants bred for for carbon storage.
  20. 20. That might sound like a lot, but it’s only a bit more than half of current U.S. farm acreage.
  21. 21. While actual numbers will vary, if a ton of compost sequesters half a ton of CO2 in soil...
  22. 22. 10 tons of compost per acre – the amount required to raise soil organic matter content by 1% -- sequesters 5 tons of CO2.
  23. 23. Increasing a zero SOM desert soil to the recommended 5% requires 50 tons of compost per acre and sequesters 25 tons of CO2 per acre .
  24. 24. 50 tons of compost per acre applied to 500 million desert acres requires 25 billion tons of compost for a total CO2 sequestration of 12.5 billion tons.
  25. 25. That’s more than 1/3 of the estimated 44 billion tons of CO2 emitted by human activities in a year -- stored through compost use on only a fraction of available land.
  26. 26. Can the world make that much compost?
  27. 27. Composting all MSW organics and human excreta Doing the math Global MSW/yr = 2.01 billion metric tons @ 50% organics = 1 billion metric tons organic waste producing .5 billion metric tons or about .6 billion U.S. tons of compost (assumes a 50% reduction during composting) Global excreta/yr = 128g/person/day = .28 pounds/person/day x 7.7 billion people x 365 days = 787 billion pounds = 393.5 million tons/year raw or 196.75 million tons composted Global total = 796.75 million tons of compost Applied at 50 tons per acre (adding 5% SOM) Sequestering 25 tons of CO2 per acre Covers 15.94 million acres and sequesters 637,600 tons of CO2 per year
  28. 28. Composting all animal waste Doing the math 5 tons of animal waste per person (U.S. estimate) x 7.7 billion people = 38.5 billion tons raw or 19.25 billion tons when composted Compost applied at 50 tons per acre, sequestering 25 tons CO2 per acre Covers 385 million acres and sequesters 15.4 million tons of CO2
  29. 29. Composting all human and animal waste Combining these waste streams, it might be possible to green the Sahara in 1-2 years and store as much as 32 million tons of CO2 just by adding compost.
  30. 30. But we really don’t need to ship anything to the Sahara to achieve the same goals.
  31. 31. Dedicating just 10 percent of the world’s 4.62 billion cultivated acres to compost use and carbon storage could accomplish the same thing...
  32. 32. using locally-sourced waste materials for use as compost feedstocks.
  33. 33. Even better, farmers say compost use meets or exceeds profit expectations.
  34. 34. Stemming global warming is doable and affordable. We just need to decide to do it.
  35. 35. 2. Compost’s impact on water management
  36. 36. Adding organic matter increases soil’s water- holding capacity.
  37. 37. This reduces runoff and erosion while improving percolation.
  38. 38. How does it work?
  39. 39. Compost’s light, friable texture allows water to move laterally and vertically through the soil.
  40. 40. Organic matter also buffers the impact of rain drops. Fewer soil particles are dislodged during storm events, reducing erosion.
  41. 41. There will be little to no runoff from a typical storm event (1 inch of rain or less) when soil organic matter (SOM) is at ideal levels.
  42. 42. How much will it take?
  43. 43. The USEPA estimates every 1% increase in soil organic matter content adds about 16,000 gallons of water storage capacity per acre foot.
  44. 44. A 1-inch application (~50 tons per acre) of compost would raise a zero OM desert sand to 5% and hold 80,000 gallons of water per acre.
  45. 45. That’s the equivalent of about 3 rain events measuring 1 inch each.
  46. 46. 3. Compost’s impact on pollution mitigation
  47. 47. Compost provides a favorable environment for the beneficial microbes that biodegrade many contaminants.
  48. 48. The feeding activity of organisms like fungi and bacteria breaks molecular bonds, reducing toxins to more benign compounds.
  49. 49. How does it work?
  50. 50. Compounds are molecules made of atoms from different elements held together by chemical bonds.
  51. 51. When fungi and bacteria feed, enzymes break the chemical bonds holding molecules together.
  52. 52. This digestion allows the nutrition from the plant or animal to be absorbed by the microorganism.
  53. 53. When these organisms die, they also add to the total organic matter content of the compost or soil.
  54. 54. The same microbiological processes that result in compost can also degrade toxic organic compounds in soil and water.
  55. 55. This is known as bioremediation.
  56. 56. Compost-based bioremediation technologies are breaking down petroleum contaminants, PAHs, and other toxins.
  57. 57. The remediation can be in-situ (in place) or soils can be excavated for faster treatment on- or off-site.
  58. 58. How much will it take?
  59. 59. For bioremediation, the USEPA suggests 30% contaminated soil in a composting feedstock blend for toxins like hydrocarbons, pesticides, and explosives.
  60. 60. BOTTOM LINE?
  61. 61. Better soil health = better planetary health.
  62. 62. Learn more about – • Decomposition • Carbon farming • Composting and water conservation • Soil and brownfield bioremediation • More titles in the Carbon Farming series Production costs for this title were underwritten by McGill. Its use is permitted for educational purposes if presented in its entirety and without editing or other alteration. ©McGill Environmental Systems of N.C. Inc. Questions? Call McGill HQ at 919-362-1161 or use a contact form at Transforming waste. Rebuilding soils.®