Although nitrous oxide only makes up 8% of global greenhouse gas emissions, it has nearly 300 times the global warming potential of carbon dioxide. In this presentation, CIFOR scientist Kristell Hergoualc’h explains results from collaborative research between CIFOR, ICRAF, CIRAD and PT Bakrie, which show that nitrogen fertiliser can exacerbate the production of soil nitrous oxide greenhouse gases when applied to oil palms grown on deep peat. She gave this presentation on 23 February 2012 at the International Conference on Oil Palm & Environment (ICOPE) held in Bali, Indonesia. The conference had the theme ‘Conserving forest, expanding sustainable palm oil production’.

1. CO2, CH4 and N2O emissions from an oil palm
plantation on deep peat as affected by N fertilisation
Kristell Hergoualc’h
Handayani E, Indrasuara, Samosir Y, van Noordwijk M, Bonneau X, Verchot L
THINKINGbeyond the canopy
23 February 2012 – ICOPE, Bali

2. Climate change and greenhouse
gases
 Increase in temperatures
Catastrophic
+ consequences
1°C
 Anthropogenic cause:  GHG emissions
F-gaz
GHG GWP
 Share GHG N2O
8%
1%
CH4 CO2 1
14%
CO2 CH4 25
77%
NO2 298
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IPCC (2007)

3. Greenhouse gases and agriculture
IPCC (2007)
Global share GHG Agriculture
Atmospheric N2O (ppb)
N fertilizer consumption
 46% N2O: Nitrogen fertilisation
(million tons N)
 45% CH4 (livestock, rice fields)
 9% CO2 (biomass combustion)
Baumert et al. (2005)
www.ferilizer.org/ifa/statistics
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4. Oil palm
 World’s most rapidly
expanding crop
(Indonesia, Malaysia)
Expansion to the detriment of natural forests
Large C losses(Murdiyarso et al. 2010; Hergoualc’h & Verchot 2011)
Biodiversity losses (Danielsen et al. 2008)
Biofuel C debt (Fargione et al. 2008)
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5. Oil palm
 Both on mineral (89%)
& peat soils (11%)
(Koh et al. 2011)
Voluntary RSPO and Government mandatory rules
forbid forest conversion and use of deep peat
 Large doses of N fertiliser application:
Mineral soils: 50 – 230 kg N ha-1 y-1
Peat soils :50 – 160 kg N ha-1 y-1
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6. Research questions and hypothesis
 How does N fertilisation affect GHG emissions in an oil
palm plantation on deep peat?
Short term and moderated  in CH4& CO2 emissions
Long term and large  in N2O emissions
 How does the emission factor related to N2O emissions
arising from N fertilisation in an oil palm plantation on
peat compare with IPCC estimates?
Emission factor > IPCC estimates (recently opened peat with low N availability)
 Can optimisation of N fertilisation  GHG emissions per
unit product?
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7. Location and soil characteristics
 Climate
2466 mm y-1, 26.5°C
Driest months: June – Sept.
 Peat properties
Fibric
Depth (8.5 m)
pH (3.6)
Corg (42%)
Norg(1.2%)
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8. Experimental plot
 Deforested in 04,
acquired by PT. Bakrie
in 07 in a state of fallow
 Planted Dec. 09;
measurements Sep. 10
 148 palms ha-1
 Water table -56 cm
 Fertiliser trial
Factorial design: 3 N x 3 P x 3 K, 2 Ca (54 plots, 8 rows x 4 palms)
N0: 0 kg N ha-1
N1:14 kg N ha-1 (20 kg N ha-1 2010, 48 kg N ha-1 2011)
N2: 28 kg N ha-1(40 kg N ha-1 2010, 96 kg N ha-1 2011) the canopy
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9. “In situ” measurements
 Soil and air temperatures, soil moisture, water table depth
 Soil effluxes of N2O, CO2, CH4 (closed chamber method)
 Sampling frequency
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10. Methods
 4 replicate chambers per N dose
 Soil CO2 efflux: “in situ” IRGA
 Soil N2O, CH4
4 samples/chamber Transportation to the Analysis by gas
(t0’, t10’, t20’, t30’) laboratory chromatography
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11. Extrapolation at the plot scale and
emission factor
FZ Zone Share plot N2O assigned
NFZ 92% N0
FZ 8% N1 / N2
NFZ
Example
N2O N1 Plot = 8% N2O N1 + 92% N2O N0
 Emission factor Ef
Slope regression between N dose and GHG emissions
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12. N2O emissions in the fertilised zone
700
N0
N2O (g N-N2O ha-1 d-1)
600 N1
500 N2
400
300
200
100
0
-100
-1 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29
Days after fertilization
 N2ON2> N2ON1> N2ON0 (P < 0.0001)
N dose Cumulated N2O emissions
 Cumulated emissions (kg N-N2O ha-1 28 days)
N0 0.3 ± 0.3
N1 2.4 ± 1.1
N2 8.8 ± 1.7
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13. N2O emissions at the plot scale and
emission factor (Ef)
 Cumulated emissions plot scale
N dose Cumulated N2O emissions
(kg N-N2O ha-1 28 days)
N0 0.3 ± 0.3
N1 0.5 ± 0.4
N2 1.0 ± 0.6
1.2
(kg N-N2O ha-1 28 days)
 Emission factor
Cumulative N2O plot
1.0
0.8
0.6
Ef = 2.5% ± 0.1% 0.4
y = 0.025x + 0.03
0.2 R² = 0.94
0.0
0 10 20 30
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N dose (kg N ha-1)canopy

14. CH4 emissions fertilised zone & plot scale
90
N0
CH4 (g C-CH4 ha-1 d-1)
70 N1
N2
50
30
10
-10
-30
-1 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29
Days after fertilization
 No significant between N doses treatments (P = 0.3)
 Cumulated emissions
N dose Cumulated CH4 emissions FZ Cumulated CH4 emissions Plot Scale
(kg C-CH4 ha-1 28 days) (kg C-CH4 ha-1 28 days)
N0 0.2 ± 0.2 0.2 ± 0.2
N1 0.6 ± 0.5 0.2 ± 0.2
N2 0.4 ± 0.4 0.2 ± 0.2 THINKING beyond the canopy

15. CO2 emissions fertilised zone & plot scale
450
N0
CO2 (kg C-CO2 ha-1 d-1)
N1
350
N2
250
150
50
-50 -1 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29
Days after fertilization
 CO2 N2> CO2 N1 , CO2 N0 (P = 0.0002)
 Cumulated emissions
N dose Cumulated CO2 emissions FZ Cumulated CO2 emissions Plot scale
(Mg C-CO2 ha-1 28 days) (Mg C-CO2 ha-1 28 days)
N0 1.9 ± 0.5 1.9 ± 0.5
N1 2.1 ± 0.2 1.9 ± 0.5
N2 2.7 ± 0.3 1.9 ± 0.5
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16. Oil palms response to fertiliser application
400
N0
Collar girth (cm)
N0
Palm Height (cm)
140
N1 N1
N2 300
100 N2
60 200
20 100
0 6 12 18 24 0 6 12 18 24
280 Months After Planting Months After Planting
Frond length (cm)
N0 35
Green leaf number
N0
240 N1 N1
N2 25 N2
200
160 15
120 5
6 12 18 24 6 12 18 24
0.8 Months After Planting Months After Planting
Hanging female bunches palm-1 24 MAP
N0
Vigor index
0.6 10
N1
8
0.4 N2
6
0.2 4
0.0 2
12 18 24 0
Months After Planting N0 N1 N2
No between N1 & N2 treatments
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17. Discussion
 No correlation with soil and air temperatures, soil
moisture, water table depth: Short period observation
 Comparison with literature
No study on the effect of N fertilisation on GHG emissions
from oil palm plantation
Melling et al. (06, 05): No intensive sampling after
fertilisation, largest N2O fluxes during wet season
N2 O CH4 CO2
(g N-N2O ha-1 d-1) (g C-CH4 ha-1 d-1) (kg C-CO2 ha-1 d-1)
This study (N0) 12.2 ± 4.7 6.0 ± 2.7 71.0 ± 10.6
Melling et al. 14 1.2 53
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18. Discussion
 Very strong effect of N fertilisation on N2O emissions:
Ef = 2.5%
Peat recently opened and drained? Young age of the palms?
 IPPC guidelines for GHG inventories (2006)*
Ef = 1% [0.3% – 3%]
Ef calculated as yearly N2O / N fertilisation rate
 Effect N fertilisation on palm growth
+ effect N1 dose but no N1 & N2 doses also
observedon coconut palms(Bonneau et al., 93)
*Agriculture, Forestry & Other Land Use, Vol. 4, Chap. 11 (N2O emissions from managed soils, and CO2
emissions from lime and urea application) THINKING beyond the canopy

19. Conclusions
 Complementary studies on GHG for improving Ef
- Experimental design improved with measurements in both
fertilised and non-fertilised zones (results under analysis)
- Yearly measurements including & fertilisation period in a 7-
year old plantation
 GHG emission vs. Crop response to fertiliser
N2ON2 = 2 N2ON1
CropN2 CropN1 Reduction of emissions per unit
product feasible
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20. Thank you
www.cifor.cgiar.org
CIFOR advances human well-being, environmental conservation, and equity by conducting
research to inform policies and practices that affect forests in developing countries.
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