assessing soil carbon sequestration...soil carbon sequestration in the usa and canada,...
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AssessingSoil Carbon Sequestration
Alan J.Franzluebbers
Ecologist
Watkinsville GA
TN
MSAL
GA
FL
VA
NC
SC
MD
…in the southeastern USA and beyond
Carbon Cycle
AtmosphericCO2
Plantrespiration
Animalrespiration
Soil respiration
Photosynthesis
Soilorganisms
Soilorganicmatter
DissolvedCO
in water2
Leachate
AtmosphericN2
Mineralization
Denitrification
BiologicalN fixation
Carbonateminerals
Fossil fuels
CO2
NN ON
2
2
O
NHvolatilization
3
NHfixation
4
Plantuptake
Fertilizer
CarbonInput
CarbonOutput
SoilCarbon
Sequestration
Carbon Cycle
Focus on maximizing carbon input
Management Approaches
Integrated management• Pest control• Crop / livestock systems
ARS Image Number K5141-4
Plant selection• Species, cultivar, variety• Growth habit (perennial / annual)• Rotation sequence• Biomass energy crops
Tillage• Type• Frequency
Fertilization• Rate, timing, placement• Organic amendments
Focus on minimizing carbon loss from soil
ARS Image Number K7520-2
Management Approaches
Reducing soil disturbance• Less intensive tillage• Controlling erosion
Utilizing available soil water• Promotes optimum plant growth• Reduces soil microbial activity
Maintaining surface residue cover• Increased plant water use and
production• More fungal dominance in soil
ProductivitySoil
OrganicMatter
Water relations BiodiversityNutrient cycling
Greenhouse gasmitigation
Soil Organic MatterValues and ecosystem services
Minimal disturbance of the soil surface is critical in avoiding soil organic matter loss from erosion and microbial decomposition
Soil Carbon Sequestration
Soil Carbon SequestrationTillage influence on depth distribution of crop residues
Data from Allmaras et al. (1996) Soil Sci. Soc. Am. J. 60:1209-1216
Proportion of Oat Residue Applied (%)0 10 20 30 40 50 60
SoilDepth(cm)
-30
-24
-18
-12
-6
0
Moldboard plow(inversion tillage)
Proportion of Oat Residue Applied (%)0 10 20 30 40 50 60
SoilDepth(cm)
-30
-24
-18
-12
-6
0
Moldboard plow(inversion tillage)
Chisel plow(non-inversiontillage)
Soil Carbon SequestrationDepth distribution of crop residues without tillage
Data from Ortega et al. (2002) Agron. J. 94:944-954
Crop Residue (Mg . ha-1)
0 1 2 3 4 5
SoilDepth(cm)
-10
-8
-6
-4
-2
0
NT wheat-fallow
OnSurface
Crop Residue (Mg . ha-1)
0 1 2 3 4 5
SoilDepth(cm)
-10
-8
-6
-4
-2
0
NT wheat-fallow
OnSurface
NT wheat-corn-millet-fallow
Soil Carbon SequestrationSoil-profile distribution of soil organic C
Soil Organic Carbon (g . kg-1)
0 5 10 15 20 25 30
-0.5
0.0
-0.5
0.0
ApplingLS, LfS, SL, fSL
CecilSL, fSL
Soi
l Dep
th (m
)
-0.5
0.0
DavidsonCL
-0.5
0.0
GreenvillefSL, SCL
-1.0
-0.5
0.0
GrenadaSi, SiL
0 5 10 15 20 25 30 35
HoustonC
LakelandLS, LfS, S, fS
NorfolkLS, LfS, SL, fSL
RustonLS, LfS, fSL,SL, fLS, SiL
SharkeyC
GrassCropForest
From Franzluebbers (2005) Soil Till. Res. 83:120-147 with data from McCracken (1959)
The vast majority of soils in the southeastern USA and elsewhere have very low concentration of soil organic C below the surface 0.5 m
Therefore there is a justified focus on measuring soil organic C in surface soil
Soil Carbon Sequestration
Soil Organic Carbon (g . kg-1)0 10 20 30 40 50 60
SoilDepth(cm)
-30
-20
-10
0
4-yr conventional tillage
Management Systems at Watkinsville GA
16-yr conservation tillage4-yr conventional tillage
Management Systems at Watkinsville GA
15-yr tall fescue pasture16-yr conservation tillage4-yr conventional tillage
Management Systems at Watkinsville GA
Depth distribution of soil organic C
From Schnabel et al. (2001) Ch. 12, Pot. U.S. Grazing Lands Sequester C, Lewis Publ.
Bulk Density(Mg . m-3)
1.2 1.4 1.6
*
*
Soil Carbon Sequestration
Data from Franzluebbers et al. (1999)Soil Sci. Soc. Am. J. 63:349-355
Soil Organic C(g . kg-1)
0 5 10 15 20
SoilDepth(cm)
-15
-10
-5
0*
Disk tillageNo tillage
3.3 * 5.9
7.5 7.4
10.3 8.9
Soil (0-15 cm)Soil + residue
21.1 22.221.2 * 26.5
Carbon Content(Mg . ha-1)
DT NT 0.1 * 4.3
Depth distribution of soil organic C
Replicated experimentGeorgia – SCLTypic Kanhapludult4-yr studySorghum, soybean, cotton
Soil Carbon SequestrationSoil-profile distribution of soil organic C
Data from Gal et al. (2007) Soil Till. Res. 96:42-51
Replicated experimentIndiana – SiCLTypic Haplaquoll28-yr studyCorn and corn/soybean
0.620.810.44
0.38
0.36
0.32
CumulativeCarbon
SequestrationRate
(Mg/ha/yr)
SoilOrganic C
(g . kg-1)0 10 20 30
SoilDepth(cm)
-100
-80
-60
-40
-20
0
BulkDensity(Mg . m-3)
1.2 1.4 1.6
Carbon Content(Mg . ha-1)
PT NT 13.6 << 22.5
43.9 > 33.3
12.8 12.2
Soil (0-100 cm) 159.2 < 169.3
***
Plow tillageNo tillage
*
*
******27.9 << 36.442.8 < 48.2
18.2 16.7
Soil (0-30 cm) 84.1 < 107.0
Soil Carbon SequestrationSoil-profile distribution of soil organic C
SoilOrganic C
(g . kg-1)0 10 20 30
SoilDepth(cm)
-60
-40
-20
0
BulkDensity(Mg . m-3)
1.2 1.4 1.6
Carbon Content(Mg . ha-1)
PT NT 10.1 11.9
41.2 41.6
9.0 7.2Soil (0-10 cm) 19.7 < 27.0
Plow tillageNo tillage
9.5 < 15.0
30.7 24.2
Soil (0-60 cm) 100.6 100.0
*
Field survey – KY, OH, PA11 different soilsAlfisols, Ultisols, Inceptisols13 + 7 years of tillage systemCorn, soybean, alfalfa, vegetables
Data from Blanco and Lal (2008)Soil Sci. Soc. Am. J. 72:693-701
0.56
0.60
0.09
-0.05
0.14
CumulativeCarbon
SequestrationRate
(Mg/ha/yr)
Soil Organic Carbon Sequestration (Mg . ha-1 . yr-1)-1.0 -0.5 0.0 0.5 1.0
SoilDepth(cm)
-20
-15
-10
-5
0
Difference in SOC betweenconservation tillage and
conventional tillage(SOC cons - SOC conv) / years
On-farm surveyfrom 29 locations
in southeastern USA
Soil Carbon Sequestration
*
Data from Causarano et al. (2008)Soil Sci. Soc. Am. J. 72:221-230
Calculation by relative difference
Field survey – AL, GA, SC, NC, VAUltisols, Alfisols, Inceptisols12 + 6 years of conservation tillageCotton, corn, soybean, peanut
Sequestration of SOC
(Mg ha-1 yr-1)--------------------
0.41
0-20 cm 0.45 *
0.08
-0.03
Soil Carbon Sequestration
Soil Organic Carbon Sequestration (Mg . ha-1 . yr-1)-1.0 -0.5 0.0 0.5 1.0
SoilDepth(cm)
-20
-15
-10
-5
0
Difference in SOC betweenperennial pasture andconventional tillage
(SOC cons - SOC conv) / years
On-farm surveyfrom 29 locations
in southeastern USA
Data from Causarano et al. (2008)Soil Sci. Soc. Am. J. 72:221-230
*
*
Calculation by relative difference
Field survey – AL, GA, SC, NC, VAUltisols, Alfisols, Inceptisols12 + 6 years of conservation tillageCotton, corn, soybean, peanut
Sequestration of SOC
(Mg ha-1 yr-1)--------------------
0.53
0-20 cm 0.74 *
0.17
0.05
0.15Mg C/ha/yr
0.00Mg C/ha/yr
Difference0.15
Mg C/ha/yr
0.15Mg C/ha/yr
-0.10Mg C/ha/yr
Difference0.25
Mg C/ha/yr
Soil Carbon SequestrationCalculation by change with time
Years of Management0 25 50 75
SoilOrganicCarbon
(Mg . ha-1)
0
10
20
30
40
Conventionalagriculturefollowing
permanent cover
Conservationagriculture
Scenario A
Years of Management0 25 50 75
SoilOrganicCarbon
(Mg . ha-1)
0
10
20
30
40
Conventionalagriculturefollowing
permanent cover
Conservationagriculture
Scenario A
0 25 50 75
Scenario B
Conventionalagriculture
for long history
Years of Management0 25 50 75
SoilOrganicCarbon
(Mg . ha-1)
0
10
20
30
40
Conventionalagriculturefollowing
permanent cover
Conservationagriculture
Scenario A
0 25 50 75
Scenario B
0 25 50 75 100
Scenario C
Conventionalagriculture
for long history
Conventionaltillage
with adoption ofother best
managementpractices
0.15Mg C/ha/yr
0.10Mg C/ha/yr
Difference0.05
Mg C/ha/yr
Temporal and comparative approaches of value; in combination best!
Example of short-term change
Franzluebbers and Stuedemann (2008) Soil Sci. Soc. Am. J. 72:613-625
Soil Organic C (g . kg-1)0 10 20 30 40
SoilDepth(cm)
-20
-10
0
Initiation
-30
-20
-10
0
At end of 3 years
Conventional tillageNo tillage
Starting from long-term pasture condition
Soil Carbon Sequestration
Years of Management0 1 2 3
0-12 cm
CT vs NT ***
Years of Management0 1 2 3 4
0-20 cm
CT vs NT **
0 1 2 3
TotalOrganicCarbon
(Mg . ha-1)
0
10
20
30
40
50
Years of Management
0-6 cm
CT vs NT ***
PastureNo tillage (NT)Conventional tillage (CT)
Franzluebbers and Stuedemann (2008) Soil Sci. Soc. Am. J. 72:613-625
∆ SOC = −1.54 Mg/ha/yr
∆ SOC = 0.19 Mg/ha/yr
∆ SOC = 1.15 Mg/ha/yr
Soil Carbon SequestrationExample of temporal and comparative combination
Soil Carbon Sequestration
Franzluebbers et al. (2001) Soil Sci. Soc. Am. J. 65:834-841 and unpublished data
Years of Management0 1 2 3 4 5 6 7 8
SoilOrganicCarbon
(Mg . ha-1)
12
14
16
18
20
22
24
Cut for hay
Years of Management0 1 2 3 4 5 6 7 8
SoilOrganicCarbon
(Mg . ha-1)
12
14
16
18
20
22
24
Cut for hay
Unharvested
Years of Management0 1 2 3 4 5 6 7 8
SoilOrganicCarbon
(Mg . ha-1)
12
14
16
18
20
22
24
Unharvested
Cut for hay
Lowgrazing pressure
Years of Management0 1 2 3 4 5 6 7 8
SoilOrganicCarbon
(Mg . ha-1)
12
14
16
18
20
22
24
Unharvested
Cut for hay
Lowgrazing pressure
Highgrazing
pressure
Establishment of bermudagrass pasture following long-term cropping in Georgia USA (16 °C, 1250 mm)
Soil C sequestration(Mg ha-1 yr-1) (0-5 yr):--------------------------------Hayed 0.30Unharvested 0.65Grazed 1.40
Example of temporal and comparative approaches
Modeling of regional farming systems
Abrahamson et al. (2007) J. Soil Water Conserv. 62:94-102
Soil Conditioning Index-1.5 -1.0 -0.5 0.0 0.5 1.0
Change inSoil Organic CSimulated by
EPIC(Mg . ha-1 . yr-1)
0.0
0.2
0.4
0.6
0.8
1.0
Cotton - CTCotton/wheat - NTCorn/wheat - cotton/wheat - NTBermudagrass - corn/wheat - cotton/wheat - NT
SOC = 0.06 + 0.018*exp(5.90*SCI), r2 = 0.69SCI a simple, useful tool that could be used to design appropriate farming systems to maximize C sequestration in Georgia
Soil Carbon Sequestration
Soil Carbon SequestrationIn the USA and Canada, conservation-tillage cropping can sequester
an average of 0.33 Mg C/ha/yr
Data from Franzluebbers and Follett (2005) Soil Tillage Res. 83:1-8
Cold-dry region(6 °C, 400 mm)
0.27 + 0.19 Mg C/ha/yr
Northwest
Hot-dry region(18 °C, 265 mm)
0.30 + 0.21 Mg C/ha/yr
Southwest
Hot-wet region(20 °C, 1325 mm)
0.42 + 0.46 Mg C/ha/yr
Southeast
Cold-wet region(6 °C, 925 mm)
−0.07 + 0.27 Mg C/ha/yrNortheast
Mild region(12 °C, 930 mm)
0.48 + 0.59 Mg C/ha/yr
Central
No tillage needs high-residue producing cropping system to be effective
Soil Carbon Sequestration
Soil Organic Carbon Sequestrationin the Southeastern USA
----------------------------------------------------
0.28 + 0.44 Mg C/ha/yr(without cover cropping)
0.53 + 0.45 Mg C/ha/yr(with cover cropping)
Franzluebbers (2005) Soil Tillage Res. 83:120-147.
Photos of 2 no-tillage systems in Virginia USA
Since animal manure contains 40-60% carbon, its application to land should promote soil organic C sequestration
Conversion of C in poultry litter to soil organic C was 10 + 19%
Note: Manure application transfers C from one land to another Franzluebbers (2005) Soil Tillage Res. 83:120-147
Franzluebbers (unpublished data)
In a 12-year experiment on bermudagrass / tall fescue, soil organic C sequestration due to poultry litter application was 0.24 + 0.47 Mg C/ha/yr
Soil Carbon SequestrationInfluence of animal manure application
Temperate or frigid regions (23 + 15%)
Thermic regions (7 + 5%)
Moist regions (8 + 4%)
Dry regions (11 + 14%)
Percentage of carbon applied as manure retained in soil(review of literature in 2001)
Soil Carbon SequestrationInfluence of animal manure dependent on climate
Opportunities exist to capture more carbon from crop and grazingsystems when the two systems are integrated:
Soil Carbon Sequestration
Utilization of ligno-cellulosic plant materials by ruminantsManure deposition directly on landWeeds can be managed with management rather than chemicals
Integration of crops and livestock
Franzluebbers and Stuedemann (2008)Soil Sci. Soc. Am. J. 72:613-625
Influence of pasture establishment
Data from Wright et al. (2004) Soil Biol. Biochem. 36:1809-1816and Franzluebbers et al. (2000) Soil Biol. Biochem. 32:469-478
SOC (Mg ha-1 yr-1) 10 yrs 25 yrs 50 yrsHayed BG (GA) 0.29 0.21 0.13Grazed BG (TX)Grazed TF (GA)
SOC (Mg ha-1 yr-1) 10 yrs 25 yrs 50 yrsHayed BG (GA) 0.29 0.21 0.13Grazed BG (TX) 0.50 0.33 0.19Grazed TF (GA)
SOC (Mg ha-1 yr-1) 10 yrs 25 yrs 50 yrsHayed BG (GA) 0.29 0.21 0.13Grazed BG (TX) 0.50 0.33 0.19Grazed TF (GA) 0.91 0.55 0.31
Years of Management0 10 20 30 40
SoilOrganicCarbon
(g . kg-1)0-15 cm
0
2
4
6
8
10
12
From a long-term bermudagrass grazing study in Texas (Rouquette)
Stand Age of Grass (years)0 10 20 30 40 50
SoilOrganicCarbon
(Mg . ha-1)
0
10
20
30
40
50'K-31' Tall fescue
'Coastal' bermudagrass
[0-20 cm depth] Georgia
Years of Management0 10 20 30 40 50
MaximumSoil Organic CAccumulation
(%)
0
20
40
60
80
100
Soil Carbon Sequestration
Franzluebbers (2005) Soil Tillage Res. 83:120-147
Nitrogen Fertilization (kg . ha-1 . yr-1)0 100 200 300
Changein
SoilOrganicCarbon
(Mg . ha-1 . yr-1)
0.0
0.4
0.8
1.2
1.6
Conventional Tillage
Nitrogen Fertilization (kg . ha-1 . yr-1)0 100 200 300
Changein
SoilOrganicCarbon
(Mg . ha-1 . yr-1)
0.0
0.4
0.8
1.2
1.6
Conventional Tillage
No Tillage
Nitrogen Fertilization (kg . ha-1 . yr-1)0 100 200 300
Changein
SoilOrganicCarbon
(Mg . ha-1 . yr-1)
0.0
0.4
0.8
1.2
1.6
Conventional Tillage
No Tillage
Carbon cost ofN fertilizer
(0.98 to 2.82 kg C . kg-1 N)
Nitrogen Fertilization (kg . ha-1 . yr-1)0 100 200 300
Changein
SoilOrganicCarbon
(Mg . ha-1 . yr-1)
0.0
0.4
0.8
1.2
1.6
Conventional Tillage
No Tillage
Carbon cost ofN fertilizer
(0.98 to 2.82 kg C . kg-1 N)
Therefore, soil carbon sequestration needs to be evaluated with a system-wide approach that includes all costs and benefits
For those of us working on greenhouse gas issues, this provides us with a formidable challenge
Soil Carbon SequestrationNitrogen fertilization effect
1 kg N2O-N ha-1 = 127 kg C ha-1
Nitrous Oxide EmissionReview of recent research
Total of 12 papers in a special Issue “N2O Emissions from Agricultural Soils in Canada”Can. J. Soil Sci. Volume 88, No. 2, April 2008
Tillage effects on N2O emission from soils under corn and soybeans in eastern Canada, Gregorich, Rochette, St-Georges, McKim, Chan
Nitrous oxide and carbon dioxide emissions from monoculture and rotational cropping of corn, soybean and winter wheat, Drury, Yang, Reynolds, McLaughlin
Effect of fertilizer nitrogen management on N2O emissions in commercial corn fields, Zebarth, Rochette, Burton, Price
Nitrous oxide, carbon dioxide and methane emissions from irrigatedcropping systems as influenced by legumes, manure and fertilizer, Ellert, Janzen
Spring thaw and growing season N2O emissions from a field planted with edible peas and a cover crop, Pattey, Blackburn, Strachan, Desjardins, Dow
Nitrous Oxide EmissionInfluence of cropping
Drury et al. (2008) Can. J. Soil Sci. 88:163-174
Woodslee ONBrookston clay loamIn Years 2, 3, and 4Fertilizer – 170 kg N/ha corn,83 kg N/ha wheat, none for soybean
Crop rotationCrop
Corn Soybean WheatMonoculture 2.62 + 1.82 0.84 + 0.52 0.51 + 0.15
Emission (kg N2O-N ha-1)
Corn/soybean 1.34 + 0.52 0.70 + 0.43 –
Corn/soybean/wheat 1.64 + 0.76 0.73 + 0.24 0.72 + 0.33
Importance of (1) N fertilizer rate, (2) type and amount of residue from previous crop, and (3) residual N.
Nitrous Oxide EmissionInfluence of season, crop, and tillage
Gregorich et al. (2008) Can. J. Soil Sci. 88:153-161
Ottawa ONLoam soilCorn-wheat-soybean rotationIn Years 9, 10, and 11Fertilizer (112 kg N/ha) corn only
N2OEmission
(kg N . ha-1)
0.0
0.5
1.0
1.5
2.0
2.5
Apr-May Aug-SepJun-Jul
n=224
n=400
n=176
0.0
0.5
1.0
1.5
2.0
2.5
Corn Soybean
Plow tillageNo tillage
Importance of soil nitrate from fertilizer
Nitrous Oxide EmissionInfluence of residues, tillage, and fertilizer
Gregorich et al. (2005) Soil Till. Res. 83:53-72
Condition
Annual crops / fall
incorporation
Annual crops / not
incorporated
Perennial crops / not
incorporatedWinter/spring (n= 6-10) 2.41 + 1.79 1.19 + 0.79 0.29 + 0.39
Emission (kg N2O-N ha-1)
Condition Moldboard plow No tillageTillage (n=15) 1.60 + 3.16 1.96 + 4.66
Condition − N fertilizer + N fertilizerAnnual crops (n=14-57) 1.53 + 1.00 2.82 + 2.78Perennial crops (n=6-9) 0.16 + 0.21 0.62 + 1.10
Nitrous Oxide EmissionInteraction of tillage with soil type
Rochette (2008) Soil Till. Res. 101:97-100
Soil Aeration
N2OEmission
(kg N . ha-1)
0
1
2
3
4
5
6
7
8
Good Medium
Conventional tillageNo tillage
Poor
p = 0.06
45 site-years of data reviewedBrazil, Canada, France, Japan,New Zealand, United Kingdom, USA
Nitrous Oxide EmissionInfluence of N fertilizer
Gregorich et al. (2005) Soil Till. Res. 83:53-72
1.19% of applied fertilizer N emitted as N2O
Compared favorably with the IPCC coefficient of 1.25%
Note the high variation in data despite the close comparison
Franzluebbers and Brock (2007)Soil Till. Res. 93:126-137
Response0-20-cm depth
Silage Crop RemovalInitially 0.5 yr-1 1-2 yr-1
At end of 7 years
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
Soil Carbon SequestrationInfluence of crop residue removal
On-farm researchNorth Carolina PiedmontCorn silage each year vs corn silage less often
Reduced water infiltration, especially with >50% removal
Increased soil erosion, most likely with >50% removal
Reduced soil organic C and N storage (dependent upon soils, climate, etc.)
Soil organic matter is a key component that controls many other soil properties
Reduced water storage and increased surface soil temperature
Increased soil strength
Reduced soil aggregation
Reduced soil biological activity
Soil Responses to Crop Residue Removal
Soil Carbon SequestrationSummary
Soil organic carbon can be sequestered with adoption of conservation agricultural practices
Enhanced soil fertility and soil qualityMitigation of greenhouse gas emissionsSoil surface change is most notableLong-term changes are most scientifically defensible
Soil Carbon SequestrationAcknowledgements
FundingAgricultural Research Service
(ARS)US-Department of EnergyMadison County Cattleman’s
AssociationUSDA-National Research
Initiative – Soil ProcessesCotton IncorporatedGeorgia Commodity
Commission for CornThe Organic CenterARS GRACEnet team