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Carbon Sequestration

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Rattan Lal

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CFAES Rattan Lal Center for Carbon Management and Sequestration,

The Ohio State University, Columbus, OH 43210 USA

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7th International Conference on Vetiver,29-31st May,2023,Chiang Mai,Thailand

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Santiago de Chile

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Mineralization

Shades of Carbon

Photosynthesis

Humification

Erosion/Leaching

Secondary carbonates

Pyrolysis/Fire

Atmosphere

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GRAY CARBON

GREEN CARBON

Soil Respiration

BROWN CARBON

BLUE CARBON

WHITE CARBON

BLACK CARBON

Combustion

RED

CARBON

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CO2

Sequestration

to Reduce

Atmospheric

Abundance

Sequestering atmospheric

CO2 into long-lived pools

Geologic

Sequestration

  1. Old oils wells
  2. Unmineable coal mines
  3. Saline aquifers

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Pedologic

Sequestration

  1. Organic Carbon

(i) Agricultural soils

(ii) Degraded soils

(iii) Wetlands

  1. Secondary carbonates
  2. Biochar

1. Chemical scrubbing

2. Mineralization

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Chemical

Sequestration

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  1. Deep injection

2. Fe-Fertilization

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Oceanic

Sequestration

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Biotic

Sequestration

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  1. Afforestation, Reforestation
  2. Biofuel plantations

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Geoengineering options

to reduce insulation

MMV& permanence refer to Geoengineering

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Photosynthesis

GPP = 123 PgC/yr

NPP = GPP-Ra = 63 PgC/yr

NEP = NPP-Rh = 10 PgC/yr

NBP = NEP-Lc = 3 PgC/yr

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Ra = Autotrophic plant respiration

Rh = Heterotrophic Microbial Respiration

Lc = Losses of C by fire, disturbances, erosion etc.

6CO2 + 6H2O C6H12O6 + 6O2

2nCO2 + 2nH2O 2(CH2O)n + 2nO2

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https://www.researchgate.net/figure/Rendzina-or-humus-calcareous-soil-Bulgarian-classification-1976-Rendzic-Leptosol-WRB_fig2_312825283

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Constituents of Soil Carbon Pool

Soil Carbon Pool

Organic

Inorganic

Pedogenic

Lithogenic

Carbonates

Bicarbonates

Live

- Fauna

- MBC

Undecomposed

(Detritus)

Decomposed

Protected

Unprotected

DOC

POC

MOC

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Weathering of Silicates

CO2 + CaSiO3 CaCO3 + SiO2

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CO2 + MgSiO3 MgCO3 + SiO2

-Urey Reactions

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http://wwwuser.gwdg.de/~kuzyakov/soils/WRB-2006_Keys.htm

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Elemental Ratio

Cereal Residues

Humus

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Elemental Ratio

Cereal Residues

Humus

C:N

100

12

C:P

200

50

C:S

500

70

C:N

100

12

C:P

200

50

C:S

500

70

Crop Residues

Humus

Biochemical Transformations

+ (N, P, S etc.)

Nutrients Required to Convert Biomass into Humus

Sequestering 12 Mg of C would need 1 Mg of N.

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Rate of Carbon Sequestration

Wetland

1500

1000

CRP/Afforestation

Turf

No-Till

Rangeland

Rate (kg/ha/yr)

Land Use

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High

Low

Medium

Medium

Temperature

Moisture

Wet

Dry

Cool

Hot

Carbon Sequestration in Relation to Climate

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