Climate Change Mitigation - Climate Resilient Agriculture for Ensuring Food Security - page 319

Mitigation actions involve reducing the fre-
quency or extent of fi res through more effective
fi re suppression, reducing the fuel load by vegeta-
tion management, and burning at a time of year
when less CH 4 and N 2 O are emitted (Korontzi
et al. 2003 ). Although most agricultural-zone
fi res are ignited by humans, there is evidence that
the area burned is ultimately under climatic con-
trol (Van Wilgen et al. 2004 ). In the absence of
human ignition, the fi re-prone ecosystems would
still burn as a result of climatic factors.

Therefore, lifetime emissions are reduced (Lovett
and O'Mara 2002 ). However, emissions over the
whole system may not always decrease as the
result of such practices. For example, intensive
selection for higher yield in dairy cattle may
reduce fertility. The reduced fertility requires
more replacement heifers in the herd which
increases whole system emissions (Lovett et al.
2006 ).
Table 13.12 summarizes the techniques avail-
able for methane mitigation in livestock
management.

13.2.4.5 Species Introduction
Introducing grass species with higher productiv-
ity, or carbon allocation to deeper roots, has been
shown to increase soil carbon. For example,
establishing deep-rooted grasses in savannahs
has been reported to yield very high rates of car-
bon accrual (Fisher et al. 1994 ), although the
applicability of these results has not been widely
confi rmed (Conant et al. 2001 ). However, it is
very important to consider the ecological impacts
of species introduction.
In the Brazilian Savannah (Cerrado Biome),
integrated crop-livestock systems using
Brachiaria grasses and zero-tillage are being
adopted (Machado and Freitas 2004 ). Introducing
legumes into grazing lands can promote soil
carbon storage (Soussana et al. 2004 ), through
enhanced productivity from the associated N
inputs, and perhaps also reduced emissions from
fertilizer manufacture if biological N 2 fi xation
displaces applied fertilizer N (Diekow et al.
2005 ).

13.3 Energy Management

13.3.1 Agriculture for Biofuel
Production

Biomass from the agriculture sector can be used
to produce biofuels - solid, liquid, and gaseous.
Biofuels substitute fossil fuels for energy deliv-
ery. If biomass is grown in a sustainable cycle to
produce biofuels, such agriculture practices miti-
gate GHG emissions due to fossil fuel not being
combusted. Biofuels can be derived from biomass
sources such as corn, sugarcane, sorghum, soy-
bean, crop residues, oil palm ( Elaeis guineensis ),
switch grass, Miscanthus , bioengineered algae,
and Jatropha curcas seeds, trees, and grasses.
First-generation biofuel crops (such as sugarcane
and maize) from which sap or grain ethanol are
obtained are already being used. In addition, sec-
ond-generation cellulosic ethanol crops (e.g.,
Miscanthus ) appear promising.
Agricultural crops and residues are the major
sources of feedstocks for energy to displace fossil
fuels. A wide range of materials such as grain,
crop residue, and cellulosic crops (e.g., switch
grass, sugarcane, and various tree species) are
used for the production of biofuel (Eidman 2005 ).
These products are processed further to generate
liquid fuels such as ethanol or diesel fuel (Richter
2004 ). These fuels release CO 2 when burned, but
this CO 2 is of recent atmospheric origin (via pho-
tosynthesis) and displaces CO 2 which otherwise
would have come from fossil carbon. The net
benefi t to atmospheric CO 2 , however, depends on

13.2.5 Longer-Term Management
Changes and Animal Breeding

Productivity increases through better manage-
ment and breeding practices often reduces meth-
ane emissions per kg of animal product (Boadi
et al. 2004 ). However, directly selecting cattle for
reduced methane production is still impractical
due to diffi culties in accurately measuring meth-
ane emissions (IPCC 2007a , b , c ).
Through improved effi ciency, meat-producing
animals reach slaughter weight at a younger age.