Soil Organic Carbon Sequestration in
the Southeastern USA:
Potential and Limitations
MD
Alan J.
Franzluebbers
Ecologist
VA
NC
TN
SC
AL
MS
GA
FL
Watkinsville GA
Soil Carbon Sequestration
Depth distribution of soil organic C
-1
Soil Organic Carbon (g . kg )
0
0
10
20
30
40
50
60
-10
Soil
Depth
(cm)
Management Systems at Watkinsville GA
-20
15-yr tall fescue pasture
16-yr conservation tillage
4-yr conventional tillage
-30
From Schnabel et al. (2001) Ch. 12, Pot. U.S. Grazing Lands Sequester C, Lewis Publ.
Soil Carbon Sequestration
Calculation by relative difference
.
-1
Soil Organic Carbon (g kg )
0
Soil
Depth
(cm)
0
5
10
-5
15
20
25
Sequestration
of SOC
(Mg ha-1 yr-1)
-------------------0.53 **
Pasture
(24 + 11 years)
0.17 **
-10 Conventional
Tillage
Cropping
-15
-20
Survey of 29 farm locations in AL, GA, SC, NC, VA
0.05 ns
0-20 cm
0.74 **
Data from Causarano et al. (2008) Soil Sci. Soc. Am. J. 72:221-230
Soil Carbon Sequestration
Calculation by change with time
Scenario A
40
Scenario B
Conservation
agriculture
Scenario C
0.15
Mg C/ha/yr
0.15
Mg C/ha/yr
30
Soil
Organic
20
Carbon
(Mg . ha-1)
-0.10
Mg C/ha/yr
Conventional
0.00
Conventional
Mgtillage
C/ha/yr
with adoption of
other best
management
Difference
practices
agriculture
for long history
10
Difference
0.25
Mg C/ha/yr
Conventional
agriculture
following
permanent cover
0
0
25 50 75
0
25 50 75
0.15
Mg C/ha/yr
0
0.15
Mg C/ha/yr
0.10
Mg C/ha/yr
Difference
0.05
Mg C/ha/yr
25 50 75 100
Years of Management
Temporal and comparative approaches of value; in combination best!
Soil Carbon Sequestration
Calculation by change with time
24
Establishment of
bermudagrass
22
pasture following
long-term
20
Soil
cropping in
Organic
Georgia USA
Carbon 18
(16 °C, 1250 mm)
(Mg . ha-1)
Low
grazing pressure
High
grazing
pressure
Unharvested
Unharvested
16
Soil C sequestration
(Mg ha-1 yr-1) (0-5 yr):
-------------------------------Hayed
0.30
Unharvested 0.65
Grazed
1.40
14
Cut for hay
12
0
1
2
3
4
5
6
7
8
Years of Management
Franzluebbers et al. (2001) Soil Sci. Soc. Am. J. 65:834-841 and unpublished data
Soil Carbon Sequestration
In the USA and Canada, conservation-tillage cropping can sequester
an average of 0.33 Mg C/ha/yr
Cold-dry region
(6 °C, 400 mm)
0.27 + 0.19 Mg C/ha/yr
Northwest
Northeast
Central
Southwest
Southeast
Hot-dry region
(18 °C, 265 mm)
0.30 + 0.21 Mg C/ha/yr
Cold-wet region
(6 °C, 925 mm)
−0.07 + 0.27 Mg C/ha/yr
Mild region
(12 °C, 930 mm)
0.48 + 0.59 Mg C/ha/yr
Hot-wet region
(20 °C, 1325 mm)
0.42 + 0.46 Mg C/ha/yr
Data from Franzluebbers and Follett (2005) Soil Tillage Res. 83:1-8
Soil Carbon Sequestration
Literature review from the southeastern USA
Franzluebbers (2005) Soil Till. Res. Franzluebbers (2005) Soil Tillage Res. 83:120-147.
Soil Carbon Sequestration
Literature review from the southeastern USA
Franzluebbers (2005) Soil Till. Res. Franzluebbers (2005) Soil Tillage Res. 83:120-147.
Soil Carbon Sequestration
Impact of cover cropping in the southeastern USA
Soil Organic Carbon Sequestration
in the Southeastern USA
---------------------------------------------------0.28 + 0.44 Mg C/ha/yr
(without cover cropping)
Photos of 2 no-tillage
systems in Virginia USA
0.53 + 0.45 Mg C/ha/yr
(with cover cropping)
Franzluebbers (2005) Soil Tillage Res. 83:120-147.
Soil Carbon Sequestration
Stratification ratio of soil organic C
Franzluebbers (2002) Soil Till. Res. 66:95-106
Soil Carbon Sequestration
Stratification ratio of soil organic C
Data from Causarano et al. (2008) Soil Sci. Soc. Am. J. 72:221-230
Soil Carbon Sequestration
Influence of tillage system following pasture
Soil Organic C (g . kg-1)
0
0
10
20
30
Starting from
long-term
pasture
condition
-10
Soil
Depth
(cm)
-20
40
Initiation
0
-10
-20
Conventional tillage
No tillage
At end of 3 years
-30
Franzluebbers and Stuedemann (2008) Soil Sci. Soc. Am. J. 72:613-625
Soil Carbon Sequestration
Influence of tillage system following pasture
0-6 cm
50
0-20 cm
0-12 cm
Conventional tillage (CT)
No tillage (NT)
Pasture
40
Total
30
Organic
Carbon
.
-1 20
(Mg ha )
∆ SOC = 0.19 Mg/ha/yr
10
∆ SOC = −1.54 Mg/ha/yr
CT vs NT ***
0
0
1
2
3
CT vs NT **
CT vs NT ***
0
1
2
3
0
1
2
3
4
Years of Management
Franzluebbers and Stuedemann (2008) Soil Sci. Soc. Am. J. 72:613-625
Soil Carbon Sequestration
Influence of animal manure application dependent on climate
Percentage of carbon applied as manure retained in soil
(review of literature in 2001)
Temperate or frigid regions (23 + 15%)
Thermic regions (7 + 5%)
Moist regions (8 + 4%)
Dry regions (11 + 14%)
Soil Carbon Sequestration
Integration of crops and livestock
 Opportunities exist to capture more carbon from crop and grazing
systems when the two systems are integrated:
 Utilization of lignocellulosic plant materials
by ruminants
 Manure deposition directly
on land
 Weeds can be managed
with management rather
than chemicals
Franzluebbers and Stuedemann (2008)
Soil Sci. Soc. Am. J. 72:613-625
Soil Carbon Sequestration
Grazing of cover crops under no tillage (0-6 cm)
Total
Organic
Carbon
.
-1
(Mg ha )
25
Soil
Microbial
Biomass
Carbon
.
-1
(kg ha )
1000
800
20
Net
Nitrogen
Mineralization
.
-1
-1
(kg ha [24 d] )
100
80
*
*
Grazed
15
Grazed
600
60
Ungrazed
Ungrazed
Grazed
Ungrazed
10
400
0
1
2
Years
3
40
0
1
2
3
0
1
2
3
Years
Years
Franzluebbers and Stuedemann (2008) Soil Sci. Soc. Am. J. 72:613-625
Soil Carbon Sequestration
Nitrogen fertilization effect
1.6
Carbon cost of
N fertilizer
(0.98 to 2.82 kg C . kg-1 N)
Change
in
1.2
Soil
Organic
Carbon
-1 0.8
-1 .
.
(Mg ha yr )
1 kg N2O-N ha-1
=
0.13 Mg C ha-1
No Tillage
0.4
Conventional Tillage
0.0
0
100
200
300
Nitrogen Fertilization (kg . ha-1 . yr-1)
Franzluebbers (2005) Soil Tillage Res. 83:120-147
Nitrous Oxide Emission
Interaction of tillage with soil type
8
7
6
5
N2O
Emission 4
.
-1
(kg N ha ) 3
p = 0.06
Conventional tillage
No tillage
2
1
0
Good
Medium
Poor
Soil Aeration
45 site-years of data reviewed
Brazil, Canada, France, Japan,
New Zealand, United Kingdom, USA
Rochette (2008) Soil Till. Res. 101:97-100
Soil Carbon Sequestration
Influence of crop residue removal
At end of 7 years
Response
0-20-cm depth
Silage Crop Removal
Initially
0.5 yr-1
Bulk density (Mg m-3)
1.43
1.37
ns
1.39
Macroaggregate stability (g g-1)
0.74
0.87
*
0.81
Soil organic C (mg g-1)
11.7
14.3
*
12.5
On-farm research
North Carolina Piedmont
Corn silage each year vs corn silage less often
1-2 yr-1
Franzluebbers and Brock (2007)
Soil Till. Res. 93:126-137
Off-Site Impacts
Water quality implications
Pennsylvania
Land use
Soil (g/kg – 0-5 cm depth)
Runoff loss (kg/ha)
Organic C
Mehlich-3 P
Sediment
Dissolved P
Total P
CT crop
13.7
0.32
767
0.02
0.52
NT crop
25.2
0.33
312
0.03
0.27
Grass
16.6
0.40
104
0.03
0.19
Oklahoma
Land use
Water
runoff
(mm/yr)
Runoff loss (kg/ha/yr)
Sediment
Nitrate N
Total N
Dissolved
P
Total P
CT wheat
61
6515
1.3
15.0
0.2
2.8
NT wheat
111
625
1.4
7.2
0.7
1.4
Grass
48
100
0.1
1.2
0.1
0.1
Data from Sharpley and Kleinman (2003) J. Environ. Qual. 32:2172-2179
and Sharpley and Smith (1994) Soil Tillage Res. 30:33-48
Methane Emission
ca. 30% of total CH4 emission in USA is from agriculture (US-EPA, 2007)
Assumptions:
0.15 + 0.08 kg CH4 head-1 d-1 [Harper et al. (1999) J. Anim. Sci. 77:1392-1401]
19 Mha of pasture land in southeastern USA (USDA-NASS, 1997)
12 million head of cattle in southeastern USA (USDA-NASS, 1997)
Resulting in:
0.62 head ha-1
34 kg CH4 ha-1 yr-1
0.37 to 1.20 Mg CO2-C equivalent ha-1 yr-1
Agriculture’s contribution to greenhouse gas emissions reviewed:
Johnson et al. (2007) Environ. Poll. 150:107-124
Soil Carbon Sequestration
Summary
Soil organic carbon can be sequestered with adoption of
conservation agricultural practices
 Enhanced soil fertility and soil quality
 Mitigation of greenhouse gas emissions
 Soil surface change is most notable
 Long-term changes are most scientifically defensible
Soil Carbon Sequestration
Acknowledgements
Funding
Agricultural Research Service
(ARS)
US-Department of Energy
Madison County Cattleman’s
Association
USDA-National Research
Initiative – Soil Processes
Cotton Incorporated
Georgia Commodity
Commission for Corn
The Organic Center
ARS GRACEnet team