Johannes LehmannDepartment of Crop and Soil Sciences, Cornell University

John GauntGY Associates, UK

Marco RondonTSBF-CIAT, Cali, Colombia

Bio-char Sequestration in SoilA New Frontier

Sequestration of Carbon in Soil – often a finite sink!

Year

1860 1880 1900 1920 1940 1960 1980 2000

So

il C

arb

on

[mg

g-1

]

5

10

15

20

25

30

35

40

Continuously manured

Manured from 1852-1871

No organic inputs

Hoosfield Barley Experiment, Rothamsted, UK

(Data courtesy of Rothamsted Research, UK)

Slow and finite increases of SOM

Year

1860 1880 1900 1920 1940 1960 1980 2000

So

il C

arb

on

[mg

g-1

]

5

10

15

20

25

30

35

40

Continuously manured

Manured from 1852-1871

No organic inputs

Sequestration of Carbon in Soil – often a labile sink!

Upon management changes, SOM decreases rapidly again – issue of permanency

(Data courtesy of Rothamsted Research, UK)

Hoosfield Barley Experiment, Rothamsted, UK

Bio-char Sequestration in Soil

• More permanent soil carbon sink than any suggested alternatives

• Chemical recalcitrance not constraint by ability of the soil to provide physical protection

• Easily accountable• Costs covered by improvement of soil fertility

= application of incompletely combusted organic material to soil (charcoal, biomass-derived black carbon)

Ubiquity of Bio-char (Biomass-Derived Black Carbon) in Soil

Not an alien substance!

Naturally occuring maximum concentrations 40% of soil organic matter

Australia: Skjemstad et al., 1996, Aust J Soil Res 34, 251-271 Europe: Schmidt et al., 1999, Eur J Soil Sci, 50, 351-365South Africa: Bird et al., 1999, Global Biogeochem Cycles, 13, 923-932USA: Skjemstad et al., 2002, Soil Sci Soc Am J, 66, 1249-1255USA: Glaser and Amelung, 2003, Global Biogeochem Cycles, 17, 1064

(Forest soil from Ghana)

Large amounts of stable aromatic carbon structures in Bio-char

Even very old particles of bio-char (black carbon) retain their high aromaticity. This is an indication of the recalcitrance of bio-char leading to high permanency in soil

Energy [eV]

280 285 290 295 300 305 310

Abs

orba

nce

(arb

itrar

y un

its)

Charcoal

Black C

Non-black C

aromatic-Cphenolic-C

carboxyl-Ccarbonyl-C

Lehmann et al., 2005, Global Biogeochemial Cycles 19: GB1013

Bio-char

NEXAFS spot spectra of particle center, black C from anthropogenic soil age 6,700 years(Near-Edge X-ray Absorption Fine Structure)

Energy [eV]

280 285 290 295 300 305 310

Abs

orba

nce

(arb

itrar

y un

its)

Charcoal

Black C

Non-black C

(6,700 years old)

(fresh)

Chemical Stability of Bio-char - NEXAFS

Chemical Stability of Bio-char

vvvvvvvvv

Liang, Lehmann et al., unpubl. data

Time (days)

0 50 100 150 200 250 300 350

C m

iner

aliz

atio

n [m

g C

O2-

C g

-1 C

]

0

50

100

150

200

LSD0.05

Soils with low BC (<10%)

Soils with high BC (>60%)(pairs with identical texture and mineralogy)

Soil organic carbon [g kg-1]

0 10 20 30 40 50 60 70

Pot

entia

l cat

ion

exch

ange

cap

acity

[

mm

olc

kg-1

]

0

100

200

300

400

500

forest profiles

High Cation Exchange Capacity of Bio-char

Greater CEC per unit carbon in soil with high amounts of bio-char

Sombroek et al., 2003, in Lehmann et al., Kluwer Ac Publ.

Anthropogenic Soils with >20% BC of SOC

with 1-10% BC

Carbon Forms on Bio-char ParticlesHighly aromatic in the centerOxidized near the surface

1 m Energy [eV]

280 285 290 295 300 305 310

Inside

Outside

Abso

rba

nce

(arb

itra

ry u

nits

)

PCR and cluster analysis

Lehmann et al., 2005, Global Biogeochemial Cycles 19: GB1013

(Both Unfertilized) © J

. Maj

or, 2

003

High Black CLow/no Black C

Application of bio-char >500 years BP!

Major, DiTommaso, Lehmann, Falcão, 2005, AGEE, in review

Soil Fertility of Bio-char-rich SoilsCentral Amazon, Brazil:

Opportunities for Bio-char Production

• From agricultural, forest and urban wastes• Through energy production systems using bio-fuels• From wastes of charcoal production• Within shifting cultivation

Basic Benefit of Biomass Conversion to Bio-char

Biomass carbon100%

Biomass carbon100%

Soil Soil

Bio-char carbon50%

100 years

Biomass carbon<10%

Soil Soil

Bio-char carbon>30%

Atmosphere730

Ocean38,000

Soil1500

Plants500

Geological Reservoirs5,000-10,000

Labile organic matter 300

Intermediate organic matter 1050

Stable organic matter 150

59

(IPCC, 2001)

60

1

12060

The Natural Carbon Cycle(in Pg)

Atmosphere730

Ocean38,000

Soil1500

Plants500

Geological Reservoirs5,000-10,000

Labile organic matter 300

Intermediate organic matter 1050

Stable organic matter 150

5.4

1.9

1.91.7

59

(IPCC, 2001)

60

1

Land uptakeLand usechange

12060

The Anthropogenic Disturbance

Fossil fuel

Atmosphere730

Ocean38,000

Soil1500

Plants500

Geological Reservoirs5,000-10,000

Labile organic matter 300

Intermediate organic matter 1050

Stable organic matter 150

0.16

5.41.9

1.7

Slash-and-char

Renewablefuel

Slash-and-char

Renewable fuel

-0.2

-0.2

?

59

-0.16

Agricultural waste

0.2

Renewablefuel

0.02

Agricultural waste

0.2

Waste

(Lehmann, Gaunt, Rondon, in review)

Bio-char Opportunities

Atmosphere730

Ocean38,000

Soil1500

Plants500

Geological Reservoirs5,000-10,000

Labile organic matter 300

Intermediate organic matter 1050

Stable organic matter 150

0.16

5.41.9

1.7

Slash-and-char

Renewablefuel

Slash-and-char

Renewable fuel

-0.2

?

59

-0.16

Agricultural waste

0.2

Renewablefuel

0.02

Agricultural waste

0.2

Waste

(Lehmann, Gaunt, Rondon, in review)

Land uptakeLand usechange

9.5With projected adoption of bio-fuels by 2100 (Berndes et al., 2003)

-0.2

Tradable GHG Emission Reductions

System change Net emissions Reduction FF Subst.* Em. Reductions

From: Slash-and-burn 3294

To: Slash-and-char 1702 1592 0 1592

From: Wood to soil 3666

To: Bio-char energy 1903 1763 1147 2910

From: Bio-fuel 3294

To: Bio-char energy 1903 1391 1147 2538

kg CO2 per ton woody biomass

(Lehmann, Gaunt, Rondon, in review) *for natural gas

Tradable GHG Emission Reductions

Not considered:- Emission reductions other than CO2 (e.g. CH4, N2O)- Increased biomass production

(Lehmann, Gaunt, Rondon, in review)

Tradable GHG Emission Reductions

Benefits of Bio-char sequestration over any other soil C sequestration:

(Lehmann, Gaunt, Rondon, in review)

• Easy accountability (determined by application)

• Low risk for C trading (high permanency)

• Kyoto mechanisms applicable (tradable commodity is

avoided emissions rather than sequestered C)

Key Messages

More permanent C sequestration than any other C sequestration method in soil

More effective for increasing soil fertility than any other C sequestration method in soil

More favorable to current C trading mechanisms than any other C sequestration method in soil