Carbon Sequestration in Carbon Sequestration in AgroAgro--EcosystemsEcosystems
Charles W. RiceSoil Microbiologist
Department of Agronomy
KK--State Research and ExtensionState Research and Extension
Atmospheric Concentrations of CO2, Methane (CH4), and Nitrous Oxide (N2O) from 1000 A.D.
From IPCC (2001)
Energy supply
0
1
2
3
4
5
6
7
<20
<50
<100 <2
0
<50
<100
GtCO 2-eq
Transport Buildings Industry Agriculture Forestry Waste
Non-OECD/EI TEITOECDWorld total
US$/tCO 2-eq
Global economic mitigation potential for different sectors at different carbon prices
IPCC, 2007
0
2
4
6
8
10
12
14
16
18
20
2005 2020 2035 2050 2065 2080 2095
Car
bo
n E
mis
sio
ns
(Pg
C p
er y
)
Soil C Sequestration
Energy Intensity
Fuel Mix
WRE550
BAU
Carbon Emissions Reductions: WRE 550 with Soil Carbon Sequestration Credits
From: Rosenberg, N.J., R.C. Izaurralde, and E.L. Malone (eds.). 1999. Carbon Sequestration in Soils: Science, Monitoring and Beyond. Battelle Press, Columbus, OH. 201 pp.
Agriculture
• A large proportion of the mitigation potential of agriculture (excluding bioenergy) arises from soil C sequestration, which has strong synergies with sustainable agriculture and generally reduces vulnerability to climate change.
• Agricultural practices collectively can make a significant contribution at low cost – By increasing soil carbon sinks, – By reducing GHG emissions, – By contributing biomass feedstocks for energy use
• There is no universally applicable list of mitigation practices;practices need to be evaluated for individual agricultural systems and settings IPCC Fourth Assessment Report, Working Group III
Agricultural management plays a major role in greenhouse gas emissions and offers many
opportunities for mitigation• Cropland
– Reduced tillage
– Rotations– Cover crops
– Fertility management
– Erosion control
– Irrigation management
No-till seeding in USA
• Grasslands– Grazing management
– Fire management– Fertilization
10/6/2008 7[ERS 2004]
CO2CO2
Harvestable Yield
Harvestable Yield
SunlightSunlight
ClimateClimate SoilsSoils ManagementManagement
Soil Organic MatterSoil Organic Matter(Humus)(Humus)
Microbial ActivityMicrobial Activity
Soil C Sequestration with conversion to No-tillage
Site Crop MT C ha-1 y-1 (Mt CO2/a/y)
CO & KS Wheat 0-0.30 0-0.45
Kansas Sorghum 0.088 – 0.605 0.13-0.90
KS, MI, OH Maize 0.300 – 0.80 0.45-1.18
Kansas Soybean <0-0.128 0-0.19
Brazil 0.51-1.84 0.75-2.72
Global 0.57 0.84
Kansas CRP 0.800 1.18
Carbon sequestration rate over 29y (Fabrizzi and Rice 2008)
Treatment C sequestration Rate (Mg C/ha/y)
No-till 0.384
Reduced-till 0.346
Tilled 0.269
Soybean 0.066
Sorghum 0.292
Wheat 0.487
Physical Protection
Chemical
Microbial composition and activity
Substratequality
Plant characteristics
H2OTemperature
Clay
Biologicalfactors
Organics
Clay
Organic C
CO2
O2
Disturbance
Conservation of Soil Carbon
Hie
rarc
hy
of
imp
ort
ance
Mineralogy
Bars of the same color for a given PLFA biomarker are not different (p<0.10). Lines are ± 1 standard error.
Microbial community - Phospholipid fatty acid levels (0-5 cm depth)
Actinomycetes
16:1w7c18:1w7c
cy19:0 10Me18:018:2w6,9c i15:0 i16:0
i17:010Me17:0
No
-Till
So
rgh
um
Till
age
So
rgh
um
Pra
irie
Gra
ss
0
2
4
6
8
10
12
14
Mo
le %
Gm- BacteriaFungi Gm+ Bacteria
• Fungal Role (18:2w6 biomarker)
• Significant tillage X residue interaction (p<0.05)
0
0.02
0.04
0.06
0.08
CT + No R CT + Residue NT + No R NT + Residue
c*
a
b
c
Mol
e F
ract
ion
Frey et al. (1999) found greater fungal networks optically in NT as compared to CT for the same soil. White and Rice, 2007
5 cm
From: Juca Sá
Physical Protection
Chemical
Microbial composition and activity
Substratequality
Plant characteristics
H2OTemperature
Clay
Biologicalfactors
Organics
Clay
Organic C
CO2
O2
Disturbance
Conservation of Soil Carbon
Hie
rarc
hy
of
imp
ort
ance
Mineralogy
Soil Aggregation
Aggregate Size Class
MacroaggregatesMicroaggregates
0
10
20
30
40
50
60
>2000
g a
gg
reg
ate
100
g-1
soil Restored prairie
No-tillage Sorghum
Tillage Sorghum
<53
aabb
53-250
aa
b
250-2000
a* b
b
More macroaggregates were present in RP after 3 y, as compared to the agro-
ecosystems. *Bars with the same letter within size class are not different (p<0.05). Lines are + 1 std error. White and Rice, 2007
san
d-f
ree
agg
reg
ates
)
Organic carbon
0
5
10
15
20
25
10 20 30 40 50
Extraradical hyphae (m g -1)
Org
anic
C
(g k
g-1
Increases in fungal hyphae increases the amount of carbon sequestered in the soil. Formation of soil aggregates physically protects soil carbon from decomposition.
Data from Wilson and Rice; Photo from Mike Miller and Julie Jastrow
r= 0.605 P<0.0001
rootroot
hyphaehyphae
YMollisol = 1.48 SOC - 8.2
R2 = 0.9245
YVertisol= 1.56 SOC - 2.83
R2 = 0.1292
YOxisol= 0.58 SOC - 6.9
R2 = 0.3344
0
10
20
30
40
50
60
70
80
0 10 20 30 40 50 60 70
SOC (g C kg-1)
Am
ou
nt o
f mac
roag
gre
gat
es
(g 1
00g
-1 s
oil)
Fabrizzi, 2006
Plant C
SOM SOM
CO2 CO2
FungiFungi
Micro-aggregates
No-Till = Lower disturbance
Soil MacroaggregateSoil Macroaggregate
Tillage = Higher disturbance
Plant C
SOM SOM
CO2 CO2
FungiFungi
Micro-aggregates
No-Till = Lower disturbance
Soil MacroaggregateSoil Macroaggregate
Tillage = Higher disturbance
Plant C
SOM SOM
CO2 CO2
FungiFungi
Micro-aggregates
No-Till = Lower disturbance
Soil MacroaggregateSoil Macroaggregate
Tillage = Higher disturbance
White and Rice, 2007
Macroaggregates & SlowlyAvailable C & N
Bacteria
CO2
CO2
COCO22
SAP Fungi N N PP
CC
C N
C NC N
C N
C N
C N
C N
AM FungiC N
N
N
C N
Belowground interactions
NO3, N2O-N2
Grazers
Carbon Stocks and Depth
Soil C stocks after 18 years
0 20 40 60 80 100 120
0-60
30-60
15-30
5-15
0-5NTCT
22
*
*
*
E
A
Change in management
Years of cultivation
SO
C le
vels
(M
g C
ha
-1)
O
Soil C sequestration rates for 15 years(Mg C/ha/y)
Depth Fertilizer NTilled
Fertilizer NNo-till
Manure NTilled
Manure NNo-till
cm
0-5 0.161 0.351 0.393 1.182
0-15 0.254 0.497 0.792 1.402
0-30 0.336 0.717 0.839 1.387
0-60 0.146 1.325 0.733 1.141
24
NT > TilledWhat is baseline?
E
D
C
AChange in management
Years of cultivation
SO
C le
vels
(M
g C
ha
-1)
O
Net effect of NT for 15 yearsNT (0-15y) –Till (0-15y)
Depth No N0.5
Fertilizer N Fertilizer N0.5
Manure N Manure N
cm Mg/ha/y
0-5 0.187 0.450 0.190 0.468 0.789
0-15 0.182 0.371 0.243 0.402 0.610
0-30 0.174 0.311 0.381 0.417 0.548
0-60 -0.443 -0.191 1.179 0.961 0.408
26
27
Relative Yield, Economic, and Sequestration Characteristics for adopting NT continuous Corn, NE Kansas
NT
Mean Yield (bu/a) 86 CT 87.7
∆Net Return ($/a) 26.50
∆ Soil Carbon (tons/a/y) 0.465
∆ Total C Emissions (tons/a/y) -0.0087
∆ Net Carbon (tons/a/y) 0.481
Soil C Value ($/a/y) $4.00 value $2.76
10% additional income
10/6/2008 28
Illustrative Ranking of Carbon as a Crop in U.S. Per Proposed GHG Limits in
Senate Bill 280 (Lieberman-McCain) 1/12/07
0
5
10
15
20
25
Pro
duct
ion
Val
ue (
$B)
date
sne
ctar
ines
cuke
s
oats
bean
sal
mon
dsle
ttuce
fres
h to
mat
o
rice
oran
ges
pota
toes
grap
es
cott
on
whe
atC
AR
BON
hay
soyb
eans
grai
n co
rn
[Crop Source: USDA - National Agricultural Statistics Service – US Crop Rankings - 1997 Production Year Ranking Based on Value of Production]
Carbon at $10/MT COCarbon at $10/MT CO22e, e,
So What is the Potential?So What is the Potential?• Globally
– It is estimated that soil has the potential to offset 30% of the annual CO2 emissions
• United States– It is estimated that soil has the potential to offset 15% of
the annual CO2 emissions– Additional options for N2O and CH4
• The economic potential is ~30-50% of that value
• Globally– It is estimated that soil has the potential to offset 30% of
the annual CO2 emissions
• United States– It is estimated that soil has the potential to offset 15% of
the annual CO2 emissions– Additional options for N2O and CH4
• The economic potential is ~30-50% of that value
Measurement, Monitoring and Verification
� Detecting soil C changes– Difficult on short time scales– Amount changing small compared to total C
� Methods for detecting and projecting soil C changes (Post et al. 2001)
– Direct methods• Field measurements
– Indirect methods• Accounting
–Stratified accounting–Remote sensing–Models
Root C
LitterC
Eroded C
Cropland C
Wetland C
Eddy flux
Sampleprobe
Soil profile
Remotesensor
Respired C
Captured C
HeavyfractionC
Woodlot C
Harvested C
Buried C
Lightfraction
C
Respired C
Soil organic C
Soil inorganic C
Simulation modelsDatabases / GIS
SOCt = SOC0 + Cc + Cb - Ch - Cr - Ce
Post et al. (2001)
SummarySummary•• Soil C sequestrationSoil C sequestration
–– Available technology at low costAvailable technology at low cost–– Significant impact on emissions: Significant impact on emissions: ““Bridge to the FutureBridge to the Future””–– Need advancement in MMV to account for variabilityNeed advancement in MMV to account for variability
•• Agricultural soil C sequestrationAgricultural soil C sequestration–– Keeps land in production thus providing food security Keeps land in production thus providing food security
and rural economic development (no leakage)and rural economic development (no leakage)–– Improves soil qualityImproves soil quality–– In many cases increases profitability for the farmerIn many cases increases profitability for the farmer–– Provides other environmental benefits to societyProvides other environmental benefits to society
•• Water quality (less runoff, less erosion)Water quality (less runoff, less erosion)•• Flood controlFlood control•• Wildlife habitatWildlife habitat
–– May help adapt to climate change as well as mitigateMay help adapt to climate change as well as mitigate
•• Therefore a WinTherefore a Win--Win SituationWin Situation
• Websiteswww.soilcarboncenter.k-state.edu/
www.casmgs.colostate.edu/
KK--State Research and ExtensionState Research and Extension
Chuck RicePhone: 785-532-7217Cell: 785-587-7215 [email protected]
