5% of the total area of a plantation on peatland. Nitrous oxide is primarily emitted
from agricultural landscapes as a by-product of nitrification and denitrification. In oil
palm plantations, the application of N-fertilizers in particular accelerates the release
of nitrous oxide and also of CO 2 (by catalyzing biological processes that result in
oxidation). Cooper et al. (2020) showed that N 2 O emissions from oil palm plantations may make up 40% of the net GHGs emissions (taking global warming potential
into account).
Current sustainability measures in oil palm plantations on peatlands will only
decrease emission source strengths, but will not stop peat carbon emissions, which,
with a drainage level of 40–50 cm, will still be around 35–45 t CO 2 per ha per year.
Parish et al. (2019a) identify the following options for the oil palm sector to
minimize GHGs emissions in peatland plantations:
(a) Water management.
For plantations on peatland, good water management is the key factor to keep
emission of GHGs as low as possible. Every cm of drainage causes an emission
of around 0.91 t CO 2 per ha annually (Hooijer et al. 2010). Flooding has to be
avoided because this enhances the formation and emission of methane and
reduces yields.
(b) Fire prevention.
Burning of biomass for clearance and burning of drained peatland in dry years
is the second largest source of GHGs emission in peat swamp areas.
Uncontrolled burning in peatlands can lead to an average emission of about
600–1000 t CO 2 /ha/fire event. The implementation of zero burning and fire
prevention measures will help to reduce emissions.
(c) Soil compaction.
The compaction of the peat soil before planting has been reported to lead to
lower CO 2 emissions compared to no compaction before planting of oil palms.
The oxidation of the peat will be reduced due to the decreased porosity of the soil
(Witjaksana 2011). However, there is some evidence from Cook et al. (2018)
that compaction increases the release of dissolved organic carbon (DOC).
Compacted peat soils also release greater CH 4 during decomposition
(MK Samuel et al., in prep) and during any fire events (Smith et al. 2018).
Maintenance of grasses, ferns, mosses (natural vegetation) and other soft vegetation on bare peat soil will add to the reduction of decomposition of the peat soil
due to drainage by reducing the soil temperature and evaporation from the soil.
(d) Fertilizer practices.
The use of “coated” nitrogen fertilizer may help to reduce N 2 O emissions. It is
recommended to implement fertilizer practices that optimize N-fertilizer and
maximize organic fertilizer use including composting and minimize fertilizer
application during rainy seasons. In addition, fertilizer can increase the breakdown of the peat soil by bacteria accelerating oxidation and subsidence. Reduction of inorganic fertilizer use can thus reduce the CO 2 emissions.
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F. Parish et al.
from agricultural landscapes as a by-product of nitrification and denitrification. In oil
palm plantations, the application of N-fertilizers in particular accelerates the release
of nitrous oxide and also of CO 2 (by catalyzing biological processes that result in
oxidation). Cooper et al. (2020) showed that N 2 O emissions from oil palm plantations may make up 40% of the net GHGs emissions (taking global warming potential
into account).
Current sustainability measures in oil palm plantations on peatlands will only
decrease emission source strengths, but will not stop peat carbon emissions, which,
with a drainage level of 40–50 cm, will still be around 35–45 t CO 2 per ha per year.
Parish et al. (2019a) identify the following options for the oil palm sector to
minimize GHGs emissions in peatland plantations:
(a) Water management.
For plantations on peatland, good water management is the key factor to keep
emission of GHGs as low as possible. Every cm of drainage causes an emission
of around 0.91 t CO 2 per ha annually (Hooijer et al. 2010). Flooding has to be
avoided because this enhances the formation and emission of methane and
reduces yields.
(b) Fire prevention.
Burning of biomass for clearance and burning of drained peatland in dry years
is the second largest source of GHGs emission in peat swamp areas.
Uncontrolled burning in peatlands can lead to an average emission of about
600–1000 t CO 2 /ha/fire event. The implementation of zero burning and fire
prevention measures will help to reduce emissions.
(c) Soil compaction.
The compaction of the peat soil before planting has been reported to lead to
lower CO 2 emissions compared to no compaction before planting of oil palms.
The oxidation of the peat will be reduced due to the decreased porosity of the soil
(Witjaksana 2011). However, there is some evidence from Cook et al. (2018)
that compaction increases the release of dissolved organic carbon (DOC).
Compacted peat soils also release greater CH 4 during decomposition
(MK Samuel et al., in prep) and during any fire events (Smith et al. 2018).
Maintenance of grasses, ferns, mosses (natural vegetation) and other soft vegetation on bare peat soil will add to the reduction of decomposition of the peat soil
due to drainage by reducing the soil temperature and evaporation from the soil.
(d) Fertilizer practices.
The use of “coated” nitrogen fertilizer may help to reduce N 2 O emissions. It is
recommended to implement fertilizer practices that optimize N-fertilizer and
maximize organic fertilizer use including composting and minimize fertilizer
application during rainy seasons. In addition, fertilizer can increase the breakdown of the peat soil by bacteria accelerating oxidation and subsidence. Reduction of inorganic fertilizer use can thus reduce the CO 2 emissions.
524
F. Parish et al.