Better Farming Better Air: Implications for Nutrient Management

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Better Farming Better Air Implications for
Nutrient Management

• Elizabeth Pattey and Raymond Desjardins

Research Branch, Agriculture and Agri-Food
Canada, Ottawa, ON
Crop Nutrients Council Symposium 20th February
2008
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• Published in March 2008 both in
• English French
• Une agriculture efficace pour un air plus sain
  une analyse scientifique des liens entre les
  pratiques agricoles et les gaz à effet de serre
  au Canada.
• 10 000 hard copies 1 000 pamphlets
• Downloadable pdf version available http
  //www.agr.gc.ca/nlwis-snite/
• Scientific Editors H.H. Janzen, R.L. Desjardins,
  P. Rochette, M. Boehm D. Worth
• Authors D. Angers,K.A. Beauchemin, C. Benchaar,
  S. Bittman, M.A. Bolinder, M. Boehm, S. Claveau,
  R.L. Desjardins,J.A. Dyer, S. Gameda, B. Grant,
  E. Gregorich, L.J. Gregorich, H.H. Janzen, R.L.
  Lemke, D.I. Massé, L. Masse, T.A. McAllister, B.
  McConkey, S.M. McGinn, N.K. Newlands, E. Pattey,
  R.L. Raddatz, P. Rochette, E.G. Smith, W. Smith,
  F. Tremblay, A.J. Vanden Bygaart, D. Worth, X.
  Vergé B. Zebarth.

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AAFC Objective

• Estimate current emissions
• Evaluate mitigation practices

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GHG Programs in Agriculture and Timeline
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Canada and the Kyoto Protocol
Canadas commitment under Kyoto is 94 of 1990
emissions
Kyoto target
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GHG emissions from the Canadian Agricultural
Sector, 2005
Agriculture 8 (excluding fuel CO2) 57 Tg CO2
equivalents
Industrial processes 7
Waste 4
CH4 49
N2O 51
Energy 81
All Sector Total 747 Tg CO2 equivalents
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Carbon Dioxide Emissions from Agriculture Related
to Land Use, Land Use Change and Forestry

• Net CO2 emissions from agriculture related to LU,
  LUC and Forestry have decreased by almost 14 Tg
  of CO2 between 1990 and 2005
• increase in C sequestration in croplands
• decrease in CO2 emissions caused by forests
  converted to croplands.

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The Change in Soil Organic Carbon Content of
Agricultural Soils in Canada 19902005
By adopting BMPs such as reduced-tillage,
reduced summer fallow and the conversion of
annual to perennial crops, farmers of the Prairie
provinces increased the amount of organic carbon
in their soils. However, in Eastern Canada,
there has been a decrease in soil organic carbon
in croplands because of a shift from perennial to
annual crops such as corn and soybean.
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Agricultural N2O and CH4 Emissions in Canada,
19902005

• N2O emissions 14
• CH4 emissions 24

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• Methane Emission Factors
• per Dairy Cows (enteric manure)
• 2) per kg of Milk

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GHG Emission Factors in Canada
The rate of GHG emissions is highly variable
between animal categories and regions across the
country.
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N2O from Synthetic N IPCC Tier II methodology
for Canadas national inventory
N2OFert NFert (EFsoil-clim RFtill
RFtopo RFirrig)
N2OFert N2O emissions arising from the
application of synthetic N fertilizer NFert (kg
N) synthetic fertilizer N applied in an
ecodistrict EFsoil-clim (kg N2O-N/kg N) soil
type/climatic region emission factor includes
effect of soil texture and spring thaw RFtill
ratio factor adjusting for emissions due to
tillage practice RFtopo ratio factor adjusting
for emissions due to variation in landscape
position RFirrig ratio factor adjusting for
emissions due to irrigation
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Provincial N2O Emission Factor for 2006 IPCC Tier
II methodology for Canadas national inventory
N2OFert NFert (EFsoil-clim RFtill
RFtopo RFirrig)
  Province (kg N2O-N/kg N) NFL 0.0170 PEI 0.01
41 NS 0.0160 NB 0.0164 QC 0.0172 ON 0.0160
MB 0.0069 SK 0.0053 AB 0.0065 BC 0.0074
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N2O Emissions

• Typically, scientists assume that about 1 of the
  synthetic N added to farm fields is emitted as
  N2O, though this can vary widely with soil water
  content (hence oxygen availability), hilliness of
  the land, and soil clay content.
• Farms can also give rise to indirect
  emissionsN2O produced elsewhere from N leached
  from fields or emitted into the air as NH3.

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Reducing N2O Emissions

• adding just enough ? identify crop needs
• improved recommendations based on soil
  analyses or N budget calculations
• 
  (e.g., account for decomposition of crop
  residues)
• at the right place ? accessible to plant
  roots
• (?banding N fertilizer at a depth of 2 cm,
  compared to 10 cm, decreased N2O emissions by
  25)
• at the right time ? during active growth
  (e.g., split application in humid areas)
• using the right form ? the NO3- form in well
  aerated soil
• the NH4 form under conditions of
  imperfect aeration (very wet or compacted soils),
  as in the short run it reduces the risks
  of denitrification.
• applying N at variable rates to reflect plant
  needs at a given location (precision farming)
• slow-release fertilizers release N slowly over
  timeat a rate that better matches crop uptake.
  This avoids large accumulations of mineral
  nitrogen in the soil and minimizes the potential
  for N2O production.
• Other substances, when added to the soil, can
  inhibit nitrification, maintain the applied N in
  the NH4 form longer and result in low N2O
  emissions.
• Using manure efficiently can also help limit N2O
  emissionsnot only because less is released from
  the manure, but also because less fertilizer
  needs to be used. Perhaps the most fundamental
  way of reducing N2O from manures is to alter
  feeding rations so that less N is excreted in
  urine and feces in the first place.

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N2O Mitigation

• Other practices that can sometimes reduce N2O
  emissions from farms include
• greater use of legumes as a N source
• use of cover crops (sown between successive
  crops) to remove excess available nitrogen
• avoiding use of summer fallow (leaving the land
  unplanted, with no crop nitrogen uptake, for a
  season)
• and adjusting tillage intensity (sometimes, but
  not always, no-till practices can reduce
  emissions).

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Impact of changes in field management on N2O
emissions estimated using DNDC

• Potential reduction in emissions when converting
  conventional to no-till agriculture 
•  
•  
• Major soil groups      Area Approximate area
  kg N2O-N/ha/y CO2 eq./ha/y Mt CO2 eq./y  
•   Mha no-till in 2006 Mha 
• Brown Chernozem  4.1 1.5 -0.01 - 2 0.00 
• Dark Brown Chernozem 5.5 1.9 -0.21 -102 -0.20 
• Black Chernozem  9.9 3.6 -0.33 -161 -0.57 
• Dark Gray Luvisol  3.2 1.1 -0.56 -273 -0.31 
• Gray Luvisol  1.6 0.4 -0.06 - 29 -0.01 
• Gray Brown Luvisol  2.5 0.3 0.36 175 0.06 
• Gleysolic   2.8 0.3 0.18 88 0.03
•                 
  Mt CO2 eq. reduction in Canada
  (DNDC) -1.01          
•   Mt CO2 eq. reduction in Canada (Tier 2 IPCC)
  -0.84
• Grant B, Smith WN, Desjardins RL et al (2004)
  Estimated N2O and CO2 emissions as influenced by
  agricultural practices in Canada. Climate Change
  65315-332.
• This represents one example where the reductions
  in N2O emissions can be met but additional
  management such as banding, and precision
  agriculture should also contribute significantly
  to reducing N2O emissions but need to be
  documented with further research.

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Soil Management Technical Working Group,
involving Federal, Provincial, and Industry, was
organized in 2005 specifically to look at BMPs
that could be used for credit.

• Technically possible 
• grain corn is generally over fertilized by about
  20.
•  If applied to entire corn area, about 1.5 M ha,
  and assuming 40 kg/ha reduction in N fertilizer
  would equal 0.33 Mt CO2 equiv.
•  reduce N rates by 10 in E. Canada by 10 with
  use of BMPs such as urease inhibitors.
•   Some reduction in N2O emission is also possible
  just by converting to no-till in western Canada. 
  
• Assuming about 8 M ha 1.0 Mt CO2 equivalent
  possible (not including any C sequestration). 
• Other BMPs offer potential small N2O reductions
  although these reductions are less proven.
   Therefore, together, 1-2 Mt is technically
  possible. 

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Soil Management Technical Working Group,
involving Federal, Provincial, and Industry, was
organized in 2005 specifically to look at BMPs
that could be used for credit.

• But Challenging
• 1)       1M/y is very little when spread
  nationally.  The exact N2O reductions of many
  fertilizer BMPs are unproven and research to
  quantify the reductions comprehensively would
  consume at least this much in the first 3-4 years
  of the program. 
• 2)       Current high crop prices, if they
  persist, will drive producers to increasing N use
  and thereby N2O emissions.  Although, with
  adoption of BMPs, the N2O emissions per unit of
  agriculture production would drop, the total N2O
  emissions might not drop because overall
  production increases. 

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Greenhouse Gas Calculator

• Interactive computer program Holos
• (desktop application Beta version)
• Calculates net GHG emissions for a variety of
  farming practices
• Evaluate mitigation strategies

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Review of several Measuring Techniques
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Non-Flow Through, Non-Steady State Chamber
Measurements
Experimental design for comparing management
practices and environmental conditions
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How do chamber measurements impact flux
determination?
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Larger Dewar for more than 48 h refilling period
gtvibration-free environment Sampling cell of
1.5m long
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Flux-Gradient technique

• Performed over agricultural fields
• Concentration is measured sequentially at a
  fast-rate, typically 5-10 s
• N2O fluxes need to be measured during rainy
  conditions and spring thaw, where the technique
  is quite robust
• Easier to monitor several sites

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GRADIENT FLUX RESOLUTION USING SINGLE-PATH TDL

• 30-min 2-level TDL gradient resolution
• N2O (1ppbv noise over 10s) 16 pptv
• CH4 (7ppbv noise over 10s) 113pptv
• 30-min Flux-Gradient resolution
• zo0.1 m s-1 u0.2 m s-1 d0.66m z23.25m
  z12.25 m
• F(N2O) 7.7 ng N2O m-2 s-1

Pattey, E., Edwards, G., Strachan, I.B.,
Desjardins, R.L., Kaharabata, S. and Wagner
Riddle C., 2006. Towards standards for measuring
greenhouse gas flux from agricultural fields
using instrumented towers. Can. J. Soil Sci. 86
373-400.
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Flux Towers are the only suitable measuring
approach during Snow melt (Permanent Site,
Ottawa)
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Permanent Site, Ottawa - Snowmelt 1997
Pattey E., Edwards, G.C., Desjardins, R.L.,
Pennock, D., Smith W., Grant B., MacPherson,
J.I., 2007. Tools for quantifying N2O emissions
from Agroecosystems. Agric. For.
Meteorol.142(2-4) 103-119
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SETUP FOR QUANTIFYING N2O FLUXES FOR TWO
MANAGEMENT PRACTICES
1 TDL connected to 2 micromet. towers
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Verification of ECOSYS model estimates
Urea applied at the following rates
Meas. model
Non-linear increase of N2O emissions with N
application rate
0.218 0.254
0.120 0.120
Grant, R. and Pattey, E., 2003. Modelling
variability in N2O emissions from fertilized
agricultural fields. Soil Biology and
Biochemistry, 35(2) 225-243.
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Research Approach Parallel Streams
Develop Model
Verified Models
MeasureGHGs
time
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Flux tower system, Coteau-du-Lac Growing season
Pattey, E., Blackburn, L.G. and Strachan, I.B.,
Desjardins, R.L, Dow, D. 2008. Spring thaw and
growing season N2O emissions from a field planted
with edible peas and a cover crop. Can. J. Soil
Sci. in press.
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Using slow release fertilizer as a BMP?
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Using different forms of fertilizer as a BMP?
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AIRCRAFT-BASED MEASUREMENTS
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THE REA SAMPLING SYSTEM TDL
Aircraft REA system
Laboratory TDL Laser
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BAG ANALYSIS SYSTEM
Pattey, E. Strachan, I.B., Desjardins, R.L.,
Edwards, G.C., Dow, D., and MacPherson, I.J.
2006. Application of a tunable diode laser to the
measurement of CH4 and N2O fluxes from field to
landscape scale using several micrometeorological
techniques. Agric. For. Meteorol.136 222-236.
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Aircraft/Chamber in Western Canada, Saskatoon,
Spring 2002 Coll Dan Pennock, Ray Desjardins,
Ian MacPherson,
April 9
Canada
April 11
April 12
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Spring thaw N2O emissions in Western Canada
DNDC Model
A/C 0.048 kg N2O-N ha-1 DNDC 0.054 kg
N2O-N ha-1 Chb 0.059 kg N2O-N ha-1
Pattey E., Edwards, G.C., Desjardins, R.L.,
Pennock, D., Smith W., Grant B., MacPherson,
J.I., 2007. Tools for quantifying N2O emissions
from Agroecosystems. Agric. For.
Meteorol.142(2-4) 103-119
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Thank You