Geoscience Reference
In-Depth Information
•
It reduces wind, water and overgrazing erosion of 10 mil-
lion ha annually, essential for ensuring future food security.
•
It rehabilitates poor soils, restores organic matter content
and brings such soils back into productivity.
•
It is inherently based on lower livestock densities and can
compensate for lower yields by a more effective vegetable
production. Organic agriculture has a land use ratio of 1:7
for vegetable and animal production.
•
The potential productivity of organic farms and organi-
cally managed landscapes can be improved considerably
by scientific agro-ecological research.
•
It conserves agricultural biodiversity, reduces environ-
mental degradation impacts and integrates farmers into
high-value food chains.
Numerous attempts particularly on soil carbon sequestra-
tion have been made to assess the technical potential for GHG
mitigation in agriculture (Anonymous, 1996; Boehm et al
.,
2004; Caldeira et al
.,
2004; Ogle et al., 2004, 2005; Smith et
al
.,
2007b,c). Mitigation potentials for CO
2
represent the net
change in soil carbon pools reflecting the accumulated difference
between carbon inputs to the soil after CO
2
uptake by plants and
the release of CO
2
by decomposition in soil. Mitigation potentials
for N
2
O and CH
4
depend solely on emission reductions. As miti-
gation practices can affect more than one GHG; it is important to
consider the impact of mitigation options on all GHGs (Robertson
et al., 2000; Smith et al., 2001; Gregorich et al., 2005).
It was estimated that 400-800 MtC year
−1
(equivalent to
about 1400-2900 MtCO
2
-eq. year
−1
) could be sequestered in
global agricultural soils. In addition, 300-1300 MtC (equivalent
to about 1100-4800 MtCO
2
-eq. year
−1
) from fossil fuels could be
offset by using 10-15% of agricultural land to grow energy crops
in which crop residues will contribute 100-200 MtC (equiva-
lent to about 400-700 MtCO
2
-eq. year
−1
) to fossil fuel offsets
if recovered and burned. CH
4
emissions from agriculture would
be reduced by 15-56% through improved nutrition of ruminants
and better management of paddy. Improved management would
reduce N
2
O emissions by 9-26%. The global 2030 technical
potential for mitigation options in agriculture considering no
economic and other barriers for all gases was estimated to be
4500-6000 MtCO
2
-eq. year
−1
or 89% from soil carbon sequestra-
tion, 9% from mitigation of methane and 2% from mitigation of
soil N
2
O emissions (Caldeira et al., 2004; Smith et al., 2007b).
