Cropping systems approaches to Cropping systems approaches to managing greenhouse gas (N2O)

emissions

Michel A CavigelliMichel A CavigelliMichel A. CavigelliMichel A. Cavigelli

USDAUSDA--ARSARS Sustainable Agricultural Systems LabSustainable Agricultural Systems LabBeltsville Agricultural Research Center, MDBeltsville Agricultural Research Center, MD

Presented at UMD-BARC Symposium, Jan. 23, 2014

NN22O: An environmentally important O: An environmentally important l ll lmoleculemolecule

• GHG: 322 ppb in 2009270 ppb pre-industrial (IPCC)270 ppb pre industrial (IPCC)

• Increasing 0.6-0.9 ppb yr -1 (www.eea.europa.eu/legal)

• ~300 times as powerful a GHG as CO2300 times as powerful a GHG as CO2

• Important catalyst of stratospheric ozone depletion (Ravishankara et al. 2009)

• Impact on climate may be more complex than direct GHG

• Alterations in wind and rainfall patterns in S • Alterations in wind and rainfall patterns in S. Hemisphere (Kang et al. 2011)

GHGs and AgricultureGHGs and AgricultureGHGs and AgricultureGHGs and Agriculture

% of total anthropogenicGHG GtCO2-eq/yr

% of total anthropogenicGHG emissions

CO2 5.1-6.1 <1CH4 3.3 ~50N2O 2.8 ~60

N2O emissions predicted to increase 35-60% b 2050 by 2050 Increasing population Changing dietary patterns

IPCC. 2007.

Changing dietary patterns

Sources of NSources of N22O from soilsO from soilsSources of NSources of N22O from soilsO from soils

• Nitrification N2O

NH4+ NH4

+ NO2- NO3

-

• Denitrification• Denitrification

NO3- NO2

- NO N2O N2NO3 NO2 NO N2O N2

• Chemodenitrification, Fungi

Controls on NControls on N22O Production by O Production by DenitrificationDenitrification in Soilsin SoilsC DenitrificationDenitrification in Soilsin Soils

NO3- NO2

- NO N2O N2nar nir nor nos

C

e

Denitrification rate ImpactOxygen/Soil moisture Negative

nar nir nor nose-

Oxygen/Soil moisture NegativeNitrate PositiveCarbon, labile PositiveTemperature PositiveTemperature Positive

N2O/N2Oxygen Complex

All factors are in constant flux in soils

yg pC:NO3 NegativeMicrobial community Unknown/Complex

All factors are in constant flux in soils Complexity makes N2O measurement and mitigation

difficult to predict/ manage

Proposed NProposed N22O Mitigation StrategiesO Mitigation Strategies• Improve NUE = nitrogen use efficiency

(e.g. US corn NUE*, 1995-1999: 37%)• Source, Rate, Placement, Timing• N process inhibitors (nitrification, urease)urease)

• Cover crops• Crop selectionp•Improved irrigation management (timing, application rate, method)R d d till• Reduced tillage

• Biochar• Crop breedingCrop breeding

*REN = (crop N uptake in fertilized plot – crop N uptake in unfertilized plot)/ (fertilizer N applied in fertilized plot)

NN22O Mitigation Strategies O Mitigation Strategies Crop SelectionCrop SelectionCrop SelectionCrop Selection

N2O emissions during corn and soybean phases of

BARC Farming Systems Project

2a

N2O emissions during corn and soybean phases of conventional corn-soybean-wheat rotation

ions

-1)

1

a

N2O

em

iss

-N h

a-1

yr-

1

b

Sea

sona

l N(k

g N

2O

0Corn Soybean

S

N2OCorn = 2.7 x N2OSoybean (Cavigelli and Parkin, 2012)

Impacts of policy, e.g. corn biofuels program

NN22O Mitigation StrategiesO Mitigation StrategiesResidual impact of manureResidual impact of manureResidual impact of manureResidual impact of manure

N2O emissions during soybean phase of

BARC Farming Systems Project

3a

corn-soybean-wheat rotations

ions

1 )

2

N2O

em

iss

-N h

a-1

yr-

0

1 b

Sea

sona

l N(k

g N

2O-

0Synthetic fertilizer system Manure+cover crop system

S

Cavigelli and Parkin, 2012

NN22O Mitigation StrategiesO Mitigation StrategiesNoNo Till: Importance of TimeTill: Importance of TimeNoNo--Till: Importance of TimeTill: Importance of Time

Humid areas Dry areass

BARC Farming Systems Project

2

3

4y

emis

sion

sha

-1yr

-1)

0

1

2

soil

N2O

eT

(kg

N2O

3

-2

-1

eren

ces

in

NT

and

CT

-5

-4

-3

nnua

l diff

ebe

twee

n N

Six et al. 2004

Year 5 Year 10 Year 20 Year 12-14, FSP, BARC

An b

Cavigelli and Parkin, 2012

Modeling NModeling N22O FluxO Flux(5 l t )(5 l t )

6

(5 year means, corn plots)(5 year means, corn plots)BARC Farming Systems Project

5

1

Modeled using DAYCENT

5.663

4

-N h

a-1

y-1 Observed

3.092.71

2

kg N

2O-

1.79 2.061.67

0

1

CT NT ORG 3

Steele, DelGrosso, Cavigelli, unpublished data

Soil Microbial Community Soil Microbial Community ImpactsImpactsImpactsImpacts

BARC Farming Systems Project

Effect of crop and date on quantity of nirK gene abundance in the Farming Systems Project

121416

num

ber /

X10

8 )

in the Farming Systems Project

25-Jul 30-Aug 29-Sep

468

10

gene

cop

y g

soil

(1X

024

nirK

g

Maul and Cavigelli, unpublished data

NN22O Mitigation StrategiesO Mitigation StrategiesN Fertilizer SourceN Fertilizer SourceN Fertilizer SourceN Fertilizer Source

N2O emissions from wheat fertilized with urea and

6

2slow release urea fertilizers, BARC, 2012-13

assio

ns

yr-1

)

345

a

bbb

al N

2O e

mi

2O-N

ha-

1y

0123

Sea

sona

(kg

N2

0

Pereira, Solomon, Cavigelli et al. unpublished

NN22O Mitigation Strategies O Mitigation Strategies Organic Cover Crop Management in Organic Cover Crop Management in Organic Cover Crop Management in Organic Cover Crop Management in

Vegetable ProductionVegetable Production

4000

5000

N ha‐

1 )

a

3000

4000

ssion (g N ab

bc

1000

2000

O ‐N emis c

0

1000

BG BP NT ST

N2O

Conv. tillage Till + black plastic No-tillage Strip tillageBG BP NT ST

TreatmentChen, Hooks et al., unpublished data

(mowing)

NN22O Mitigation Strategies O Mitigation Strategies Integrated SystemsIntegrated SystemsIntegrated SystemsIntegrated Systems

NN till l ti i t ll d till l ti i t ll d C i i ll d C i i ll d NoNo--till planting into rolled till planting into rolled rye+vetchrye+vetch cover crop mixcover crop mix

Corn growing in rolled Corn growing in rolled cover cropcover crop

SidedressingSidedressing poultry litter with poultry litter with HighHigh--residue noresidue no--till till gg p yp ysubsurface subsurface banderbander

HighHigh residue, noresidue, no till till cultivationcultivation

Mirsky et al.

Quantifying NQuantifying N22O Mitigation Strategies O Mitigation Strategies Methodological IssuesMethodological IssuesMethodological IssuesMethodological Issues

Determining sampling strategies • Determining sampling strategies that optimize temporal coverage of soil N2O fluxes

1000

600

800 No TillChisel TillOrganic

200

400g

-200

01/1 2/1 3/1 4/1 5/1 6/1 7/1 8/1 9/1 10/111/112/1

Cavigelli, unpublished data

Quantifying NQuantifying N22O Mitigation Strategies O Mitigation Strategies Methodological IssuesMethodological IssuesMethodological IssuesMethodological Issues

800

900

d-1 )

N TillTrapezoidal Integration Method

300

400

500

600

700

x (g

N2O

-N h

a-1 No Till

Chisel Till

Organic

Sum (kg N2O-N ha-1 35d-1)NT = 8.58CT = 3.73O 3 5 65

0

100

200

5/12 5/17 5/22 5/27 6/1 6/6 6/11 6/16 6/21

N2O

flu Org3 = 5.65

900

500

600

700

800

900

2O-N

ha-

1d-

1 )

No Till

Chisel Till

y=38.925e-0.029x

Sum (kg N2O-N ha-1 35d-1)NT = 2.44

100

200

300

400

N2O

flux

(g N

2

OrganicCT = 1.10Org3 = 1.70

05/12 5/17 5/22 5/27 6/1 6/6 6/11 6/16 6/21

Cavigelli, unpublished data

Needed ResearchNeeded ResearchNeeded ResearchNeeded Research

M di l i di N O •More studies evaluating diverse N2O mitigation strategies

•More systems-level comparisons•Improved data collection and interpolation •Better understanding of fundamental processes