Upload
phungnhu
View
214
Download
0
Embed Size (px)
Citation preview
18/08/2008
1
Reducing N2O emissions from grazed pasture systems and options for including these in
national inventories
Tim Clough
Lincoln UniversityNew Zealand
URUGUAYN2O emissions: 9.7 MtCO2-e
Desechos Excremento humano1%
Agricultura -Suelos agrícolas (Emisiones directas)6%
Agricultura - Suelos de pastoreo (Emisiones
- 99% of N2O emissions in 2002 originated in agriculture, - 90% of them from grazing animals (dung and urine deposited by free-range grazing animals).
Agricultura - Suelos agrícolas (Emisiones indirectas)33%
pastoreo (Emisiones directas por excreta de animales)60%
(Luis Santos 2007)
222 NONNONO →→→−
Denitrification
N2O formation pathways
22223 ON NNONOOHNHNH →→→→→ −
−
3NOON2
Pathway: Nitrifier Denitrification
NitrificationDenitrification
Wrage et al. 2001 Soil Biology & Biochemistry
NH4+
- - - -
NO3-
Cation exchange
18/08/2008
2
Factors affecting denitrification rates in soils
Manage-
TemperatureTemperature
pHpH
DenitrificationDenitrificationNONO33 →→ NN22O & NO & N22
Soil type
Stocking rate Stocking type
Manage-ment
In grazed pastures urine patches are the main sources of nitrous oxide emissions and nitrate leaching
90
120
150
ion
(mg
N/L
)
Urine 1x500Urine 1x1000Urea 4x100
Nitrate leaching is greatest below the animal urine patch
Over 90% of total leaching in grazed
pasture comes from urine patches.
0
30
60
90
0 200 400 600 800
Cumulative drainage (mm)
Nitr
ate
N c
once
ntra
ti Control
< 10% of leaching comes from fertiliser
N2O emissions from urine amended soil
Canterbury moderately drained silt loam
0.8
1.0
1.2
g N
/m2 . h
our)
Cow urine
Control
0.0
0.2
0.4
0.6
9-Apr-00 28-May-00 16-Jul-00 3-Sep-00 22-Oct-00 10-Dec-00 28-Jan-01 18-Mar-01
Date
N2 O
em
issi
on (m
g
Source: Sherlock et al. (unpubl. data)
18/08/2008
3
How can we mitigate N2O emissions from excreta N?
• Change the animals diet?– modify the C/N ratio?
• Stand-off/feed pads?
Covered feed & loafing pad
(Cecile De Klein, AgResearch 2008)
Uncovered feed & loafing pad
(Cecile De Klein, AgResearch 2008)
How can we mitigate excreta N?
• Change the animals diet?– Increase C and modify the C/N ratio?– Stand-off/feed pads
Use nitrification inhibitors e g dicyandiamide– Use nitrification inhibitors e.g. dicyandiamide (DCD)
18/08/2008
4
Nitrosomonas
Nitrification inhibitor
DCD reduces the activity of the Nitrosomonas bacteria in the soil
(Bacteriostatic effect)
Ammonium + oxygen Nitrite
(NH4+)
Nitrobacter
Nitrite + oxygen Nitrate (NO3
-)
Nitrous oxide gas loss
Nitrate leaching loss
The inhibitor temporarily blocks the active site of a specific enzyme (ammonia monooxygenase)
NH4+
- - - -
NO3-
Cation exchange
Nitrification inhibitor slows
down the rate of nitrate
production and thus reduces the nitrate leaching
loss
Recommend DCD is applied in May and August because most losses occur between late autumn and early spring
CHRISTCHURCH: Mean Soil Temperature (at 10cm) and Estimated Drainage (mm)
35
40
45
50
age
(mm
)
14
16
18
20
ure
C)
DCD DCD
0
5
10
15
20
25
30
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecMonths
Est
imat
ed D
rain
a
0
2
4
6
8
10
12
Soil
Tem
pera
tu0C
Drainage (mm)
Soil Temp (C)
Drainage
18/08/2008
5
Daily N2O-flux, Templeton lysimeters Winter Run Off Trial - 2005/06
500
600
700
800
(g/h
a/da
y)
Control
eco-n (10) 21st June
U1000 (3rd June)
U1000 (3rd June) eco n (10) 21st
DCD reduced N2O emissions by 73% on Templeton soil in Canterbury, NZ (Di et al. 2007).
0
100
200
300
400
9/06/2
005
24/06
/2005
9/07/2
005
24/07
/2005
8/08/2
005
23/08
/2005
7/09/2
005
Sampling date
N2O
-N fl
ux ( U1000 (3rd June) eco-n (10) 21st
N2O emissions reduced by 67% in the Canterbury Lismore soil (Di et al., 2007)
300
400
O-N
ha-1
day-1
) Urine 1000
Urine 1000 + DCD
0
100
200
29/04/05 29/05/05 28/06/05 28/07/05 27/08/05 26/09/05Sampling date
Dai
ly N
2O fl
ux (g
N2
N2O emissions reduced by 61% in the Waikato Horotiu soil (Di et al., 2007)
300
400
N2O
-N h
a-1 da
y-1) Control
Control + DCDUrine 1000Urine 1000 + DCD
0
100
200
05/05/05 04/06/05 04/07/05 03/08/05Sampling date
Dai
ly N
2O fl
ux (g
N
N2O emissions reduced by 69% in the Taupo pumice soil lysimeters (Di et al., 2007)
40
50
N h
a-1 d
ay-1
)
ControlControl + DCDUrine 700Urine 700 + DCD
0
10
20
30
3-Aug-05 2-Sep-05 2-Oct-05Sampling date
Dai
ly N
2O fl
ux (g
N2O
-N
18/08/2008
6
Nitrate leaching reduced by 76% from urine applied to Templeton soil (Di and Cameron, 2004. NZ J Agr. Res. 47)
60
80
100
tion
(mg
L-1)
Urea 200/Urine 1000
Urea 200/Urine 1000/Eco-N (May + Aug.)
0
20
40
60
0 50 100 150 200 250 300
Cumulative drainage (mm)
NO
3- -N c
once
ntra
Nitrate-N Leaching - Waihora, Taupo
250
300
350
400
/ha/
yr)
Urine alone
Urine + eco-n
no urine
no urine + eco-n
DCD reduced nitrate
leaching by 30 – 40%
3 year trial shows that DCD inhibitor significantly reduced nitrate leaching losses from Taupo pumice soils
0
50
100
150
200
2003 2004 2005 3 year AverageN
itrat
e-N
(kg
N/
Soil lysimeter facilities in different regions
Waikato: Horotiu soil
Canterbury: Templeton and Lismore Taupo pumice soil
Lincoln UniversityControl plot
Lincoln UniversityDCD plot
18/08/2008
7
Internationally peer reviewed and published literature:
• Di, H.J., Cameron, K.C., 2002. The use of a nitrification inhibitor, dicyandiamide (DCD), to decrease nitrate leaching and nitrous oxide emissions in a simulated grazed and irrigated grassland. Soil Use and Management 18, 395-403.
• Di, H.J., Cameron, K.C., 2003. Mitigation of nitrous oxide emissions in spray - irrigated grassland by treating the soil with dicyandiamide, a nitrification inhibitor. Soil Use and Management 19, 284-290.
• Di, H.J., Cameron, K.C., 2004a. Effects of the nitrification inhibitor dicyandiamide on potassium, magnesium and calcium leaching in grazed grassland. Soil Use & Management 20 2-7Management 20, 2 7.
• Di, H.J., Cameron, K.C., 2004b. Treating pasture soil with a nitrification inhibitor, eco-nTM, to decrease nitrate leaching in a deep sandy soil under spray irrigation - a lysimeter study. New Zealand Journal of Agricultural Research 47, 351-361.
• Di, H.J., Cameron, K.C., 2004c. Effects of temperature and application rate of a nitrification inhibitor, dicyandiamide (DCD), on nitrification rate and microbial biomass in a grazed pasture soil. Australian Journal of Soil Research 42, 927-932.
• Di, H.J., Cameron, K.C., 2005. Reducing environmental impacts of agriculture by using a fine particle suspension nitrification inhibitor to decrease nitrate leaching from grazed pastures. Agriculture, Ecosystems and Environment 109, 202-212.
• Di, H.J., Cameron, K.C., 2006. Nitrous oxide emissions from two dairy pasture soils as affected by different rates of a fine particle suspension nitrification inhibitor, dicyandiamide. Biology and Fertility of Soils 42, 472-480.
Some of the data required to develop an N2O inventory consists of:
• Animal numbers• N excreta• Direct emission factors• Direct emission factors
– EF1 N2O emitted from fertiliser
– EF3PRP N2O emitted from urine and dung
• Indirect emission factors– EF5 N2O emitted from leached N
2006 IPCC guidelines for National Greenhouse Gas Inventories
For a mitigation to be included in an inventory we also must know:
• Animal numbers affected by mitigation tool?
• Changes in N excreted?• Time period of the year mitigation tool
works?• Changes in direct emission factors ?• Changes in indirect emission factors ?• Verification?
Summary of international peer reviewed literature: DCD effect on
direct N2O emissions
• The reduction in direct N2O emissionsEF3(PRP) averaged 67% ± 6% (std dev. n=4.)
18/08/2008
8
Summary of international peer reviewed literature:
DCD effect on NO3- leaching
• The reduction in nitrate leaching Frac(LEACH) averaged 74% ± 4% (std dev. n=5.)
Calculating DCD emission factors (EF)
0099.0)125
%100%501()1(''1 =××−=
monthsmonthsEFdefaultIPCCEFdefaultIPCCplusDCDEF
kg N2O/kg fertiliser-N
0079.0)125
%100%503()3(''3 =××−=−
monthsmonthsEFdefaultIPCCEFdefaultIPCCnDCDplusEF PRPPRPPRP
kg N2O/kg excreta-N
(Clough et al. 2007 Nutr. Cycl. Agroecosyst. 78:1-14. )
Table 8 Module Submodule Worksheet Sheet
2003 Agriculture (New Zealand) Agricultural soils 4.5 (3 of 5) Direct nitrous oxide emissions from animal production (grazing animals)
Pasture, range and paddock AWMS
N excretion for AWMS
PRP
Emission factor for
AWMS (EF
Total direct animal prodn.
i i
Total directanimal
dPRP (kg N)
AWMS (EF3
PRP) (kg N2O-N/kg
N)
emissions of N2O-N (Gg)
prodn.emissions
of N2O (Gg)
PRP nil DCD 1,386,897,313 0.0100 13.869 21.794PRP plus DCD 143,375,290 0.0079
0.836 1.314
#Assumes 25% of dairy cattle under DCD regime
126128130
to 1
990
(%)
nil eco-neco-n 5 month effective periodeco-n 5 month effective period but weighted emissions of 84%
Effect of DCD on N2O inventory
114116118120122124
0 10 20 30 40 50 60 70 80% dairy cattle under DCD regime
N2O
em
issio
ns r
elat
ive
18/08/2008
9
Verification ???
GPS certified records of DCD application
DCD application map – providing proof of placement
Date and time of application
Paddock details
Customer details
18/08/2008
10
GPS certification of DCD application:
Dates & areas
Cow numbers:
Dates & areas
New Zealand default and/or DCD Emission factors
Fertiliser usage/application:
(Fertiliser receipts)
Peer reviewed science
Calculate farm N2O flux(Fertiliser receipts)
Dates & areas
Calculate mitigation achieved
Calculate Carbon credit
$ $ $ $ $
$ $ $ $ $
Extra Dry Matter$
Summary• Identify main N2O sources and mitigation strategy.• Peer reviewed science of mitigation tool.
– Changes in N excreted?– Duration of mitigation effect(s)?– Changes in direct emission factors ?– Changes in indirect emission factors ?
• Verification.– Animal numbers affected by mitigation tool?– Land area affected by mitigation tool - Use technology!
e.g. GPS.
18/08/2008
11
DCD degradation and microbiology
• Soil bacteria utilise and degrade DCD.
• Numbers of nitrifiers not affected.
f ff C• N2-fixers not affected by DCD.
• Repeat application of DCD in laboratory studies has little or no effect on rate of DCD decomposition or ability of DCD to inhibit nitrification.
• Moir et al. (2007, Soil Use & Mgt) shows no change in response to DCD after four years of field data collection in NZ.
DCD degradation and soil temperature
120
160
days
Di & Cameron 2004
0
40
80
0 10 20 30
Temperature, deg C
Hal
f life
, d
International literature (4 studies)
Kelliher & Clough et al. 2008
Internationally peer reviewed and published literature:
• Di, H.J., Cameron, K.C., 2002. The use of a nitrification inhibitor, dicyandiamide (DCD), to decrease nitrate leaching and nitrous oxide emissions in a simulated grazed and irrigated grassland. Soil Use and Management 18, 395-403.
• Di, H.J., Cameron, K.C., 2003. Mitigation of nitrous oxide emissions in spray - irrigated grassland by treating the soil with dicyandiamide, a nitrification inhibitor. Soil Use and Management 19, 284-290.
• Di, H.J., Cameron, K.C., 2004a. Effects of the nitrification inhibitor dicyandiamide on potassium, magnesium and calcium leaching in grazed grassland. Soil Use & Management 20 2-7Management 20, 2 7.
• Di, H.J., Cameron, K.C., 2004b. Treating pasture soil with a nitrification inhibitor, eco-nTM, to decrease nitrate leaching in a deep sandy soil under spray irrigation - a lysimeter study. New Zealand Journal of Agricultural Research 47, 351-361.
• Di, H.J., Cameron, K.C., 2004c. Effects of temperature and application rate of a nitrification inhibitor, dicyandiamide (DCD), on nitrification rate and microbial biomass in a grazed pasture soil. Australian Journal of Soil Research 42, 927-932.
• Di, H.J., Cameron, K.C., 2005. Reducing environmental impacts of agriculture by using a fine particle suspension nitrification inhibitor to decrease nitrate leaching from grazed pastures. Agriculture, Ecosystems and Environment 109, 202-212.
• Di, H.J., Cameron, K.C., 2006. Nitrous oxide emissions from two dairy pasture soils as affected by different rates of a fine particle suspension nitrification inhibitor, dicyandiamide. Biology and Fertility of Soils 42, 472-480.
18/08/2008
12
Scale – 20 cm x 20 cm = 400 cm2Scale – 20 cm x 20 cm = 400 cm2
Nitrosomonas bacteria are widespread throughout the soil and they all need to be treated.