Climate Change Mitigation - Soil Carbon: Science, Management and Policy for Multiple Benefits - page 122

Table 9.1. Annual net mitigation potentials including non-CO 2 GHG (Mg CO 2 -eq ha - 1 year -1 ) in each climate
region for aggregate management categories.

Net mitigation potential a
(t CO 2 -eq ha - 1 year -1 )

Regions
(moisture
regime)

Sustainable land management
categories

Average yield
increase b (%) Cool Warm

Dry Agronomy 0.39 0.39 116

Nutrient management 0.33 0.33 72 c

Tillage/residues management 0.17 0.35 122

Water management 1. 1 4 1. 1 4 92

Agroforestry 0.17 0.35 81

Moist Agronomy 0.98 0.98 122

Nutrient management 0.62 0.62 118

Tillage/residues management 0.53 0.72 55

Water management 1. 1 4 1. 1 4 164

Agroforestry 0.09 0.72 61

a Eggleston et al . (2006); b Branca et al . (2013b); c considers only organic nutrient management.

higher residues. Examples of such practices
reported by Smith et al . (2007) include using
improved crop varieties, extending crop ro-
tations and rotations with legume crops.
Nutrient management corresponds to the
application of fertilizer, manure and bio-
solids, improving either the efficiency (ad-
justing application rate, improving timing,
location, etc.) or diminishing the potential
losses (slow-release fertilizer form or nitrifi-
cation inhibitors). Tillage/residue manage-
ment concerns the adoption of practices
with less tillage intensity, ranging from min-
imum tillage to no-tillage, and with or with-
out residue retention on the field. Water
management brings together enhanced irri-
gation measures that can lead to an increase
in productivity (and hence of the residues).
Agroforestry encompasses a wide range of
practices where woody perennials are inte-
grated within agricultural crops.
Estimates of the mean net mitigation
potential by these aggregated management
categories are reported in Table 9.1 . Due to
the scarcity of data, only simplified categor-
ies were used in compiling mean estimates
of C sequestration potential at the global
scale, aggregated by major climate ( Table 9.2 ;
Plate 7).
Branca et al . (2013b) synthesized pub-
lished data on the impact of the adoption of

Table 9.2. Correspondence between IPCC
climate zones used in Eggleston et al . (2006) and
simplified classification used by Smith et al . (2007)
and IPCC (2007) for reporting GHG mitigation
potentials.

IPCC climate zone Simplified

Tropical montane dry Warm dry

Tropical montane moist Warm moist

Tropical wet Warm moist

Tropical moist Warm moist

Tropical dry Warm dry

Warm temperate dry Warm dry

Warm temperate moist Warm moist

Cool temperate dry Cool dry

Cool temperate moist Cool moist

Boreal moist Boreal moist

Boreal dry Boreal dry

mitigation practices corresponding to these
categories on crop productivity (average
yield). Table 9.1 should be read with cau-
tion, because the values have been obtained
from two different data sets, and also
the main land management categories are
too broad to allow a direct relationship be-
tween the mitigation potentials and average
yield increases. But as a whole, these find-
ings suggest that management options
favourable for GHG mitigation have a posi-
tive effect on yields, and thus soil fertility.