Climate Change Mitigation - Climate Resilient Agriculture for Ensuring Food Security - page 308

Table 13.10 Change in soil organic carbon (SOC)
following land-use change (Guo and Gifford 2002 )
Land use

• Applying organic substrates such as manures,
biosolids, and composts
• Reducing tillage and retaining crop residues
• Conserving water (IPCC 2007c )
Degradation of lands can result in the emission
of greenhouse gases. Through restoration of
lands, these emissions can be reduced.
The sustainable land management (SLM)
practices identifi ed fundamentally restore
degraded soils, increasing plant growth (whether
arable crops, rangeland plants, or trees) and bet-
ter enabling them to cope with the impacts of cli-
mate change, whether they are wetter, drier, or
more variable conditions. They include:
• Revitalizing biological tillage
• Reducing compaction
• Increasing rainfall infi ltration
• Protecting natural drainage through the soil
profi les
• Increasing water storage capability
• Naturally improving soil nutrient status
Several possible benefi ts can be noted from
the restoration of degraded lands and peatlands.
First, restoring degraded lands and peatlands
improves biodiversity. Second, peatlands purify
water and can therefore be regarded as an impor-
tant water supply source. Third, restored (peat)
lands can be more effectively used as fl ood
mitigation areas. Fourth, restored peatlands
have been shown to signifi cantly reduce fi re risk
(Peat Portal Assessment Report 2008 ). Finally,
due to aesthetic quality of fully restored peat-
lands and other degraded lands, sustainable
development can be supported through ecotour-
ism activities.
Restoration of organic soils therefore has a
variety of biodiversity and environmental co-
benefi ts. However, the economic impact depends
upon whether farmers receive payment for the
GHG emission avoidance and reductions
achieved. Market-based mechanisms might be
able to support restoration of peatlands and
degraded lands as they add carbon valuation.
Restoration of degraded lands will provide higher
yields and economic returns, less new cropland,
and provide societal benefi ts via production
stability.

Percent change
in SOC Before After

Pasture Plantation −10

Native forest Plantation −13

Native forest Crop −42

Pasture Crop −59

Native forest Pasture +8

Crop Pasture +19

Crop Plantation +18

Crop Secondary forest +53

on SOC analyzed the data following land-use
changes from 74 publications (Table 13.10 ).
Wherever a land-use change decreased SOC
(Table 13.10 ), for example, native forest to crop
(−42 %), the reverse will increase SOC by a
comparable but not equal amount. The totals and
rates of change in SOC will depend on the soil
type, texture and structure, precipitation, temper-
ature, farming system, specifi c crops and trees
grown, and land management. Rates of change
ranges from 0 to 150 kg C/ha year −1 in dry and
warm regions and 100-1,000 kg C/ha year −1 in
humid and cool climates (Lal 2004 ). Providing
environmental conditions remain similar, SOC
content is likely to reach its maximum 5-20 years
after adoption of benefi cial SLM practices and
remain constant.

13.1.9 Restoration
of Degraded Lands

A variety of factors cause agricultural lands to
become degraded: excessive disturbance, ero-
sion, organic matter loss, salinization, acidifi ca-
tion, drainage, or other processes that curtail
productivity. Carbon storage within these soils
can be partly restored by practices that reclaim
productivity such as:
• Enabling revegetation, for instance, in the
form of planting vegetation

• Improving fertility through nutrient

amendments