Soil Carbon Sequestration in AgricultureSoil Carbon Sequestration in Agriculture

Scott Staggenborg and Charles W. Rice

Department of Agronomy

K-State Research and ExtensionK-State Research and Extension

Strategies to ReduceStrategies to Reduce Atmospheric CO Atmospheric CO22

Strategies

Reduce fossilfuel consumption

Identify sinks andsequestration

rate

Improve efficiencyRenewable

energy sourcesTerrestrial

Aquatic

Soils Plants

Geologic

41%4%

18%

4%

33%

CroplandCRP/WRPGrazingland*ForestlandUrban lawn

Soil C sequestration potential of differentSoil C sequestration potential of different US land Categories (% of 322 MMT C/yr) **US land Categories (% of 322 MMT C/yr) **

Improved Agricultural Practices Conservation tillageConservation buffers

Cover crops

Improved rotationsSoil organic

matter

CO2

Soil Organic Matter(Humus)

CO2

product

energy

Climate ManagementSoil Type

Crop Management Strategies for C Sequestration

Enhance C Inputs Reduce C losses

Crop Management Tillage

Crop Selection Fallow Management

Crop Rotations

Develop Crop Management Programs that:

Enhancing C Input – Fertility

0

0.1

0.2

0.3

0.4

0.5

0 N-CT 150 N-CT 0N-NT 150 N-NT

Cha

nge

in S

OC

/Yea

r (T

/a)

C-C NF 1991-1999

Enhancing C Input – Crop Selection

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Corn Wheat Soybean Grain Sorghum

Cha

nge

in S

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/Yea

r (T

/a)

Crop Management Strategies for C Sequestration

Enhance C Inputs Reduce C losses

Crop Rotations Fallow Management

•To increase soil carbon levels, we need crop rotations that reduce fallow periods.

•Especially rotations with fallow periods during the summer when temperatures result in maximum soil respiration rates.

Enhancing C Input – Intensifying Rotations

Soybean Corn Wheat

5

6

7

8

9

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0 5 10 15 20 25 30

SO

C (

T/a

)

SB-C-Wht-DCSBSB-C

Brown Co. KS

Crop Management Strategies for C Sequestration

0

0.1

0.2

0.3

3 Year 4 Year Continuous

Cha

nge

in S

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r (T

/a)

Eastern Colorado

Crop Management Strategies for C Sequestration

Enhance C Inputs Reduce C losses

Crop Management Tillage

Crop Selection Fallow Management

Crop Rotations

Develop Crop Management Programs that:

Why Tillage– Eliminate soil compaction

– Control weeds

– Eliminate residue• Harbor insects and diseases

• Tie up fertilizer N

• Barrier for herbicide

– What hard working people do

• Sense of accomplishment

• Cleansing operation

• Why not?

Because it causes soil erosion and reduces soil organic matter

Enhancing C Input – Tillage

0

0.1

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0 N-CT 150 N-CT 0N-NT 150 N-NT

Cha

nge

in S

OC

/Yea

r (T

/a)

C-C NF 1991-1999

Reducing Loss – Reducing tillage

0

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4

6

8

10

12

0 5 10 15 20 25 30

SO

C (

T/a

)

No-till SB-CConv till SB-C

Brown Co. KS

Enhancing C Input – Tillage

-0.6

-0.5

-0.4

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0

NT RT CT

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NE W-F 1970-1990

Soil organic C after 2 and 12 y of CRP

in Nebraska (Baer, Kitchen, Blair, and Rice)

36

38

40

42

44

46

48

So

il O

rga

nic

C M

g C

/ha

)

2-y CRP 12-y CRP

0.4 Tons/a/y

SoilOrganicMatter

WaterHoldingCapacity

CropYield

Soil Biodiversity

Rootgrowth

Nutrient Reserves

Soil Structure

PlantBiomass

SoilQuality

Lal, Kimble, and Follett 1997

Carbon Credits/Trading

• Carbon reduction– C reduction at point of emissions– C reduction by sequestration

• Is it cheaper to buy a credit than control emissions?

What is needed

• Sellers of C credits: Land managers

• Aggregator

• Buyers

• Monitoring/Verification

Examples of feasibility and pilot projects on soil carbon sequestration

Region Land Use Land management change

Saskatchewan, Canada Cropland Direct seeding / cropping intensification

Pacific Northwest, USA Cropland Direct seeding / cropping intensification

Midwest

Iowa, Kansas

Cropland

Grass planting

No-till

New grass plantings

Oaxaca, Mexico Crop / natural fallow secondary forest

Fruit tree intercrops with annual crops / Conservation tillage

Pampas, Argentina Cropland Direct seeding

Kazakhstan Cropland Agriculture to grassland

Izaurralde (2004)

Offsets for no-till or grasses

Offsets for grasses only

U.S. Central Region for CCX® Soil Offsets

Kansas MRLAs and Carbon Pilot Counties

Tillage Equipment• Full width inversion

– Moldboard plow– Chisel plow– Field cultivator– Tandem disk– Offset disk– Row crop cultivator

• Okay to use– No-till/ridge-till planter– No-till drill– Rolling harrow– Subsoiler/ripper – Anhydrous applicator– Manure knife

applicator

• General Guideline: After the implement has been through the field, there must still be a substantial amount of surface residue present and the soil disturbance must not be full width. If use of the implement would require that a leveling or smoothing activity follow, it would probably result in too much soil disturbance.

Mechanics of Ag Offset Aggregation in CCX®

Aggregators- accepts initial registrations from producers

- assembles annual attestations of activities from producers- receives offsets into CCX registry account from

- executes sales on CCX trading platform on behalf of growers- manage multi-grower reserve account

Individual Growers- register; undertake actions as per 4-year contract;

sign annual attestations; allow access to CCX verifiers; ultimate owner of offsets

CCX- issues offsets to aggregator’s

registry account- commissions verifiers

documentation offsets

documentation sales proceeds

2004 Carbon Offset Prices

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

2.20

$ P

er M

etri

c T

on

Consortium for Agricultural Soil Mitigation Consortium for Agricultural Soil Mitigation of Greenhouse Gasesof Greenhouse Gases

• To provide the tools and information to successfully implement soil carbon sequestration so that – the accumulation of greenhouse gases is lowered in the

atmosphere, – while providing income and incentives to farmers and

improving the soil.

Kansas State University Colorado State University

Iowa State University Michigan State University

Montana State University University of Nebraska

Ohio State University Purdue University

Texas A&M University Pacific Northwest National Labs

Questions?

Potential of U.S. Cropland for C Sequestration, Fossil Fuel Off-set,& Erosion Control

Scenario

C sequestration Fossil fuel off set

MMTC/yr

C sequestration in soil 75-208

Biofuel production (C offset) 35-63

Saving in fuel consumption 1-2

Reduction of C emission from eroded sediments

12-22

Total 123-295

Lal et al., 1999

Soil Sampling for Measuring Soil C

• Soil C storage depends on soil area and thickness or mass– Report on volume basis

• Need to sample:– Laterally across the landscape to account for spatial

variability due to: • topography• erosion• soil mapping units• management (tillage, inputs).

– Vertically through the profile to account for• horizonation, tillage, residue and root inputs

Sampling scheme

Mean SD CV% n†

Grid 1 48.36 3.94 8.2 25

Grid 1 47.84 3.61 7.5 25

Grid 1 47.83 2.77 5.8 25

Average 48.01 3.44 7.2

Composite 1 48.47 0 0 1

Composite 2 44.65 0 0 1

Composite 3 46.66 0 0 1

Average 46.59 1.91 4.1

Variability of soil C (Mg ha-1) for an agricultural site