Agriculture and greenhouse

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Agriculture and greenhouse

• Tom Denmead
• Research Fellow
• CSIRO Land and Water
• Professor G. W. Leeper Memorial Lecture
• Nov 24, 2006

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With help from

• Ben Macdonald Ian White
• Australian National University, Canberra
• Glenn Bryant David Griffith
• University of Wollongong, Wollongong
• Weijin Wang Phil Moody
• QDNRMW, Brisbane
• Deli Chen, Debra Turner, Zoe Loh, Ron Teo
  Robert Edis
• University of Melbourne
• Robert Quirk Bill Stainlay
• Cane farmers, Tweed Valley, NSW
• Charlton Sandalwood Feedlots
• Australian Greenhouse Office
• Meat Livestock Association

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Greenhouse gas emissions in Australia -- National
Greenhouse Gas Inventory (2004)
Agriculture second only to power houses
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Greenhouse gas emissions in Australia Trends
since 1990

• The Government says that Australia is well on
  the way to meeting its Kyoto target, an increase
  of 8 over 1990
• The increase to 2004 was only 2.3
• However, that was due largely to a one-off
  reduction in land clearing
• Without that, emissions have increased by 25
• Agriculture shows virtually no change

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Greenhouse gas emissions in Australia -- National
Greenhouse Gas Inventory (2004)
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Greenhouse gas emissions in Australia -- National
Greenhouse Gas Inventory (2004)
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The AGO Program on Greenhouse Action in Regional
Australia

• Some funding from the ARC, RD Corporations and
  State Agencies, but the Australian Greenhouse
  Office (AGO) is the main funding body in
  Australia for research into greenhouse gas
  emissions from agriculture.
• The AGO manages a 4-year Strategic RD Investment
  Plan of targeted research on
• managing GHG emissions and responding to climate
  change in agriculture and natural resource
  management
• with 18 projects
• Projects include
• satellite tracking of GHG emissions from
  agricultural soils
• measurements of GHG emissions from various
  agricultural enterprises
• developments of new measurement techniques, e.g.,
  open-path IR systems and methods for measuring
  enteric CH4 emissions
• life cycle assessments
• assessments of indirect greenhouse gas emissions
  (SO2, NH3, NOx)
• building management options into decision support
  tools
• Investment
• AGO, gt3M
• Partners, 16M

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AGO projects discussed in this lecture
(illustrative of new technologies being applied)

• Greenhouse gas fluxes from sugarcane soils and
  nitrogen fertilizer management
• Open-path systems (Laser and FTIR) for the
  measurement of greenhouse gases from land-managed
  systems
• The missing gases measuring emissions of
  indirect greenhouse gases from agriculture

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Greenhouse gases and sugarcane soils

• Australian sugarcane soils characterised by
• high soil moisture regimes
• high soil temperatures
• high levels of available carbon (from trash
  retention)
• high levels of soil nitrogen (from high
  fertiliser rates)
• These conditions
• are conducive to formation of the gases nitrous
  oxide and methane,
• have a strong influence on carbon dioxide
  exchange and carbon sequestering

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The gases

• Carbon dioxide (CO2)
• high soil temperatures, high soil moisture and
  high carbon should increase soil respiration, but
• models say they might also promote higher carbon
  sequestration
• Nitrous oxide (N2O)
• produced under aerobic and anaerobic conditions
• production stimulated by high temperatures, high
  soil moisture contents, high soil nitrogen and a
  carbon source
• global warming potential 310 times that of CO2
• Methane (CH4)
• formed under anaerobic, waterlogged conditions
• formation stimulated by high temperatures and a
  carbon source
• global warming potential 21 times that of CO2

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Previous studies

• Chamber measurements by Weier et al. (Aust. J.
  Agric. Res.,1996) and Weier (Aust J. Agric Res.,
  1998)
• Australian sugarcane soils emit 10kT N2O-N y-1
  equivalent to1/3 of all N2O emissions from
  agricultural soils in the country
• emissions from acid sulfate sugarcane soils are
  larger than from other soils used more commonly
  for sugarcane production
• 8.9kT CH4 y-1 are emitted from Australian
  sugarcane soils after burning, but 45kT CH4 y-1
  are consumed by trash blankets.
• Micrometeorological measurements by Denmead et
  al. (Proc. Aust. Soc. Sugarcane Technol., 2005)
• large losses of N2O from acid sulfate sugarcane
  soils when wet
• small losses when dry.
• These measurements are short-term, covering only
  a few days and not extending through the whole
  growing season

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Conclusions from previous studies

• Dalal et al. (2003) reviewed available data on
  N2O emission from Australian agricultural lands
  and stated
• Improved estimates of N2O emission from
  agricultural lands and mitigation options can be
  achieved by a directed national research program
  that is of considerable duration, covers sampling
  season and climate, and combines different
  techniques (chamber and micrometeorological)
  using high precision analytical instruments and
  simulation modelling.

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Present investigations

• A 3-year project to measure long-term (whole of
  growing season) emissions of greenhouse gases
  from sugarcane soils
• Uses chambers and micrometeorological techniques
  for emissions of CO2, N2O and CH4
• Automatic chambers used to
• provide continuous measurements of emissions from
  the soil surface,
• validate micrometeorological techniques,
• assess soil variability
• Manual chambers used to
• provide background emissions,
• study treatment effects throughout growing season
• Micrometeorological techniques
• continuous measurements of exchanges of the 3
  gases between crop and atmosphere

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Present investigations

• Measurements to be made for I year at each of 2
  sites located at Murwillumbah (burnt cane) and
  Mackay (green cane harvesting)
• Measurements commenced on ratoon crop of
  sugarcane on an acid sulfate soil at Murwillumbah
  in October, 2005 and were continuous through the
  whole growing season, 342 days
• Both the soil type and the farming practice at
  Mackay are more representative of the industry
  than those at Murwillumbah

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Murwillumbah site

• Acid sulfate soil subject to flooding at Blacks
  Drain on farm of Bill Stainlay at Murwillumbah,
  in valley of Tweed River in northern NSW
• topsoil organic clay loam with 5C, pH lt 4, pore
  space 60
• subsoil 85 clay, water table 0 to 0.7m

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Automatic chamber technique

• Used to
• provide continuous measurements of
  emissions from the soil surface,
• validate micrometeorological techniques,
• assess soil variability
• Operation
• 6 chambers
• lids closed in turn for 18 min every 3h
• Measurement
• air from chamber circulated through FTIR
  spectrometer and rate of increase in CO2, N2O,
  CH4 measured

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Automatic chambers
Emissions of N2O from 3 chambers after
160kg urea-N ha-1
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Micrometeorological techniques eddy covariance
(uses fast-response sensors measurements made 10
times per second)
LICOR open-path CO2/H2O sensor
c
CSAT sonic anemometer w
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Eddy covariance measurements of CO2 exchange and
evaporation in sugarcane field
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Micrometeorological techniques flux-gradient
(uses 30-min averages rather than instantaneous
data no fast-response sensors available for most
non-CO2 gases)
Turbulent transport coefficient KT calculated
from measurements of atmospheric dispersion
Height
Concentration gradient
Flux
Concentration
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N2O fluxes over bare field 8 days after 160kg
urea-N, using flux-gradient technique and FTIR

• Fourier Transform Infrared (FTIR) spectrometers
  measure concentrations of a suite of greenhouse
  gases simultaneously
• Above, N2O emissions increasing over time, but
  marked diurnal cycles
• Points to the need for continuous sampling
  measurements at one or even a few times a day
  (common practice with chamber systems) misleading

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Micrometeorological trace-gas flux station

• Continuous half-hourly, measurements
  throughout the growing season
• Exchange of direct greenhouse gases (CO2, N2O,
  CH4) and indirect greenhouse gases (NH3, NOx,
  SO2) between crop and atmosphere using eddy
  covariance, FTIR and trace-gas analysers
• Water, heat, momentum fluxes
• Meteorology (radiation, wind, stability,
  rainfall)
• Soil water and soil temperature
• Features
• Solar-powered field instrumentation
• Automatic, remote control
• On-line processing and data transfer via internet
  and modem to centres in Wollongong and Canberra

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Validation Testing the eddy covariance system

• The eddy covariance system gives us direct
  measurements of the rates of heat loss from the
  crop, and its evaporation and CO2 exchange.
• Above, !/2 hour measurements of crop evaporation
  through the growing season. The average rate was
  3.1mm d-1 and the total evaporation was 1089 mm
• The system also provides the transfer
  coefficient h to use in the flux-gradient
  measurements of emissions of N2O and CH4

We test the accuracy of the system by comparing
its recovery of the energy fluxes from the crop,
i.e., the sum of the evaporation and heat loss,
with the solar energy available to drive these
processes. After corrections for sensor
separation, we recover about 90 of the available
energy
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Validation Daily CO2 fluxes from 6 automatic
chambers and eddy covariance system in first 2
weeks

• CO2 emission from the soil predominates in the
  early stages of the ratoon crop
• 2 to 1 variability in chamber fluxes, but their
  average close to micrometeorological fluxes
  (blue)

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Validation Nitrous oxide fluxes from chambers
and micrometeorology after 160kg urea-N ha-1

• As for CO2, 2 to 1 variability in chamber fluxes,
  but their average close to micrometeorological
  fluxes
• Rapid rise in N2O flux 0.01 to 0.5 kgN ha-1 d-1
  in 15 days

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CO2 exchange eddy covariance measurements
LICOR Missing

• Half-hourly averages of CO2 flux between crop and
  atmosphere throughout the growing season
• Flux changes from positive (into the atmosphere)
  to negative (from the atmosphere) as the crop
  grows and photosynthesis dominates over soil
  respiration

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CO2 exchange contributions from soil and
atmosphere

• A large proportion of the CO2 sequestered by the
  crop comes from the soil, approximately 40
• The estimated net assimilation of CO2 is 50 g
  m-2 d-1
• Addition of urea fertilizer has virtually no
  effect on soil CO2 emission

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N2O emission flux-gradient technique

• Prolonged and substantial emissions of N2O
  lasting for gt5 months after fertilising
• Emissions of N2O from unfertilised plots also
  substantial, but N pool exhausted more quickly

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Soil moisture and N2O emission

• Water-filled pore space (WFPS) describes the
  degree of saturation
• There is a peak in emission rates between 70 and
  80
• N2O production is known to be at its maximum in
  this range
• Hence,N2O emission increases with rainfall,
  except for controls where N supply limited

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Soil moisture and CH4 emission

• CH4 emissions more difficult to measure because
  of large natural background
• Little correlation between CH4 emission and WFPS
  of surface soil
• But strong coupling with rainfall indicates some
  dependence on soil wetness Suggests production
  deeper in profile.

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Summary

• Net emissions to atmosphere, CO2 equivalents
• t ha-1
• CO2 -110
• N2O 21
• CH4 1
• Emission factors
• NGGI and IPCC 1.25
• Present study 19
• Question What mechanisms cause these remarkable
  rates?
• Are they physical, biological, chemical?

• Net greenhouse gas emissions
• CO2
• Emissions from soil
• Manual chambers, 57 t/ha ?
• Uptake from atmosphere
• Micrometeorology, 110 t/ha
• N2O
• Emissions from fertilized soil
• Micrometeorology, 44 kgN/ha
• Emissions from unfertilized soil
• Manual chambers, 13 kgN/ha ?
• CH4
• Emissions from fertilized soil
• Micrometeorology, 53 kg/ha

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Summary

• Emission factors used by NGGI
• Pastures
  0.4
• Irrigated crops 2.1
• Non-irrigated crops 0.3
• Cotton 0.5
• Horticulture and vegetables 2.1
• Sugarcane 1.25
• Our investigation 19
• Questions
• 1. What mechanisms cause these remarkable rates
  in our study?
• Are they physical, biological, chemical?
• 2. The usual assumption is that crops are CO2
  neutral what they take from the atmosphere is
  eventually returned there. However, our data
  shows that even if this was the case, there was a
  net emission of 22t CO2-e through nitrous oxide
  and methane.
• Is ethanol production from sugarcane really
  green? We must wait one more year

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Thank You

• CSIRO Land and Water
• Name O.T. Denmead
• Title Research Fellow
• Phone (eg. 61 2 6246 5965)
• Email tom.denmead_at_csiro.au
• Web www.clw.csiro.au

Contact CSIRO Phone [phone] 9545
2176 Email enquiries_at_csiro.au Web www.csiro.au
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Open-path technologies for measuring greenhouse
gas emissions laser and Fourier Transform
Infrared (FTIR) systems

• Lasers measure line-averaged gas concentrations
  up to 1km, FTIR less
• Lasers tripod-mounted, stand alone,
  battery-operated units FTIR requires mains power
  and liquid N
• Both suitable for point, line and small area
  sources
• Lasers are tuned to individual gases, CO2,CH4 and
  NH3 FTIR measures all the gases of interest
  (CO2, N2O, NH3, CH4) simultaneously and has
  better sensitivities

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Tests Releases
Daisy our virtual cow

• CH4, N2O, NH3 released from cylinders through
  mass-flow controllers
• Tests conducted of recoveries from point source
  and plane source emissions

40m x 15m grid of permeable pipes
40m x 15m grid of permeable pipe
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Applications Turning concentration measurements
into surface emission rates -- inferring
emissions with a backward Lagrangian stochastic
(bLs) dispersion analysis

• Use a dispersion model to trace particles
  backwards from sensor to their origins inside and
  outside the source area. Surface fluxes
  calculated from number of touchdowns in the two
  areas
• Uses a computer package called WindTrax to
  calculate surface fluxes
• Suitable for point, line or area sources (any
  shape)
• Inputs geometry of source area, height and
  location of sensor, wind speed and direction,
  atmospheric stability, gas concentrations upwind
  and downwind

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Recoveries using WindTrax

• Top
• Recovery by laser of NH3 released from ground
  level grid, 25m x 25m
• Laser 2m downwind of grid
• Path 128m
• NH3 released at 5L min
• Bottom
• Recovery by 2 lasers and FTIR of CH4 released
  from ground level grid, 40m x 15m
• Path 140m

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Applications CH4 emission from 16 grazing dairy
cows
Triangular field
Wind direction
Reflector
Meteorology
Touchdowns
The calculated CH4 emissions agree well with
inventory estimates The study now extended to
feedlots with 20,000 cattle
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Applications Measuring emissions of N gases from
a fertilized field
Measure line-averaged gas concentrations upwind
and downwind apply bLs theory through WindTrax
N2O
NH3
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Applications Measuring losses of ammonia from a
fertilized maize field in China
The portability of the laser systems makes them
very attractive for field work in remote
locations Openpath technologies provide us with
a suite of new, sensitive and flexible options
that will allow us to measure greenhouse gas
emissions in many on-farm operations where
emissions could not be determined previously
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Thank You

• CSIRO Land and Water
• Name O.T. Denmead
• Title Research Fellow
• Phone (eg. 61 2 6246 5965)
• Email tom.denmead_at_csiro.au
• Web www.clw.csiro.au

Contact CSIRO Phone [phone] 9545
2176 Email enquiries_at_csiro.au Web www.csiro.au
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The Missing Gases Trace Gas Station

• Other gases, notably the nitrogen gases, ammonia
  (NH3) and the oxides of nitrogen (NOx) play
  important roles in the greenhouse story, but are
  missing from most inventories
• IPCC estimates that indirect N2O emissions due to
  atmospheric deposition of N-compounds formed from
  NH3 and NOx originating from agriculture are as
  large as the direct emissions from agricultural
  soils or from animal production systems
• Monitoring the yearly cycle of these emissions
  will be as important as monitoring those of N2O,
  both in greenhouse terms and in terms of the
  nitrogen budget

This trace gas station is air-conditioned and
houses gas analysers and a data logger for
measurement of fluxes of indirect greenhouse
gases NH3 and NOx, as well as SO2 and H2S
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The Missing Gases

• The trace gas station is trailer mounted and is
  being used in projects in Victoria New South
  Wales and Queensland
• Contrasts in air quality atmospheric NH3
  concentrations over feedlots are hundreds of
  times those over agricultural fields

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Thank You

• CSIRO Land and Water
• Name O.T. Denmead
• Title Research Fellow
• Phone (eg. 61 2 6246 5965)
• Email tom.denmead_at_csiro.au
• Web www.clw.csiro.au

Contact CSIRO Phone [phone] 9545
2176 Email enquiries_at_csiro.au Web www.csiro.au