Composting organic waste and using compost as a soil amendment can help address several environmental issues by rebuilding soil quality and storing carbon. Specifically: 1) Compost replenishes lost organic matter and soil microbes, increasing the soil's carbon storage capacity. As soil quality improves, more carbon can be stored both above and below ground. 2) Adding organic matter through compost increases the soil's water holding capacity, reducing runoff and erosion while improving water infiltration. More carbon in the soil allows it to hold more water. 3) Compost provides a favorable environment for microbes that break down pollutants in soil and water through bioremediation. As microbes feed and die,

1. Compost to the Rescue
3 reasons to fix the soil and save the planet

2. Our planet is facing some major health issues.

3. Industrial farming and other human activities
have led to historic loss of topsoil and carbon
storage capacity.

4. Carbon dioxide (CO2) build-up in the
atmosphere is driving climate change.

5. Pollutants contaminate air, soil, and water.

6. But there is one simple action everyone can
choose to help resolve these issues.

7. By composting organic waste and
using that compost as a soil
amendment, humans can undo much
of that damage.

8. 1. Compost’s impact on
soil and carbon storage

9. Compost rebuilds the topsoil layer by
replenishing organic matter and soil microbes
lost to human activities.

10. Adding to the topsoil layer also increases
carbon storage capacity.

11. Compost “feeds” soils at the surface and
contributes carbon for long- or short-term
sequestration.

12. How does it work?

13. A typical compost is 50%-60% carbon.

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. As soil improves, so do plants. More carbon-
rich biomass above and below the surface
further increases carbon availability to soil.

16. As long as the soil remains undisturbed, that
carbon can be stored indefinitely.

17. Every pound of additional carbon sequestered
in the soil represents 3.67 pounds of carbon
dioxide removed from the atmosphere.
carboncycle.org

18. How much will it take?

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. That might sound like a lot, but it’s only a bit
more than half of current U.S. farm acreage.

21. While actual numbers will vary, if a ton of
compost sequesters half a ton of CO2 in soil...

22. 10 tons of compost per acre – the amount
required to raise soil organic matter content
by 1% -- sequesters 5 tons of CO2.

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. 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. 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. Can the world make that much compost?

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. 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. 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. But we really don’t need to ship anything to
the Sahara to achieve the same goals.

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. using locally-sourced waste materials for use
as compost feedstocks.

33. Even better, farmers say compost use meets
or exceeds profit expectations.

34. Stemming global warming is
doable and affordable. We
just need to decide to do it.

35. 2. Compost’s impact on
water management

36. Adding organic matter increases soil’s water-
holding capacity.

37. This reduces runoff and erosion while
improving percolation.

38. How does it work?

39. Compost’s light, friable texture allows water to
move laterally and vertically through the soil.

40. Organic matter also buffers the impact of rain
drops. Fewer soil particles are dislodged
during storm events, reducing erosion.

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. How much will it take?

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. 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. That’s the equivalent of about 3 rain events
measuring 1 inch each.

46. 3. Compost’s impact on
pollution mitigation

47. Compost provides a favorable environment for
the beneficial microbes that biodegrade many
contaminants.

48. The feeding activity of organisms like fungi and
bacteria breaks molecular bonds, reducing
toxins to more benign compounds.

49. How does it work?

50. Compounds are molecules made of atoms
from different elements held together by
chemical bonds.

51. When fungi and bacteria feed, enzymes break
the chemical bonds holding molecules
together.

52. This digestion allows the nutrition from the
plant or animal to be absorbed by the
microorganism.

53. When these organisms die, they also add to
the total organic matter content of the
compost or soil.

54. The same microbiological processes that result
in compost can also degrade toxic organic
compounds in soil and water.

55. This is known as bioremediation.

56. Compost-based bioremediation technologies
are breaking down petroleum contaminants,
PAHs, and other toxins.

57. The remediation can be in-situ (in place) or
soils can be excavated for faster treatment
on- or off-site.

58. How much will it take?

59. For bioremediation, the USEPA suggests 30%
contaminated soil in a composting feedstock
blend for toxins like hydrocarbons, pesticides,
and explosives.

60. BOTTOM LINE?

61. Better soil health = better planetary health.

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 www.mcgillcompost.com.
Transforming waste. Rebuilding soils.®