Soil Carbon Sequestration for Climate Change Mitigation …
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lead to increasing carbon in the soil also enhance soil fertility [7]. Different management systems can modify SOC stocks, mitigating or worsening climate change
through acting as a sink for storing C or as a source for C emission. For reducing
and managing greenhouse emissions, SOC sequestration through agricultural and
forestry management is important. Therefore, during the last few years, prediction
of SOC stocks in the different ecosystem has become a crucial issue, because of the
probable effects of C on upcoming climate change. On the other hand, understanding the effect of land cover/land use and expected climate change on SOC stocks
provides valuable information to improve approaches to land planning. However,
uncertainties in climate change studies are high so investigating several scenarios is
essential [2].
2 Emissions of CO 2 : Reasons and Mitigation
Terrestrial ecosystems release greenhouse gases (GHGs) (i.e. carbon dioxide (CO 2 ),
methane, and nitrous oxide) and act as a sink when storing carbon (C) in vegetation
and soil [4]. As levels of CO 2 and other GHGs in the atmosphere have been increasing, rising concern over the impact of these gases on world climate systems has
been elevated which led to increasing the awareness towards the global carbon cycle.
Therefore, international negotiations are held for reducing GHGs level in the atmosphere [8]. The actions for mitigating GHGs impacts increased with the adoption of
United Nations Framework Convention on Climate Change (UNFCCC) in 1992 and
the Kyoto Protocol in 1997. The prime objective of this convention is to stabilize the
level of greenhouse gases at the level that would not cause further damage; especially
anthropologically; to the climate system [9].
An estimated emission of GHGs from agriculture, forestry and land-use is approximately 24% (concentrated mainly in mainly CH 4 and N 2 O of total global atmospheric
emissions of GHGs [10]. Global cultivated soils are estimated to release about 50
Pg C into the atmosphere via mineralization of SOC [11]. Although soil is the main
terrestrial organic carbon (OC) stock, representing 75% of the Earth’s terrestrial OC,
it can act as a sink or a source of carbon and atmospheric CO 2 with direct influence
on the greenhouse effect [12].
Available data indicate that, managed soils have historically been a net source
of atmospheric CO 2 contributing to more than 20% of the annual increase of CO 2 ;
3.2 Pg C in the atmosphere, however, soils can be a net sink for C through enhancement of long-term C storage or sequestration in the soils and thus reduction in CO 2
accumulation rate in the atmosphere [6]. Therefore, measurement of CO 2 flux has
been considered as a reliable and sensitive indicator of C cycling in response to soil
management practices [13]. There are many factors affecting the rate of CO 2 flux
from agricultural soils and these factors vary temporally and regionally. These factors are representing in management practices (such as the addition of exogenous
organic inputs, quantity and quality of litter inputs), environmental conditions (i.e.
temperature and soil moisture) and the soil microbial community. It is reported soil
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lead to increasing carbon in the soil also enhance soil fertility [7]. Different management systems can modify SOC stocks, mitigating or worsening climate change
through acting as a sink for storing C or as a source for C emission. For reducing
and managing greenhouse emissions, SOC sequestration through agricultural and
forestry management is important. Therefore, during the last few years, prediction
of SOC stocks in the different ecosystem has become a crucial issue, because of the
probable effects of C on upcoming climate change. On the other hand, understanding the effect of land cover/land use and expected climate change on SOC stocks
provides valuable information to improve approaches to land planning. However,
uncertainties in climate change studies are high so investigating several scenarios is
essential [2].
2 Emissions of CO 2 : Reasons and Mitigation
Terrestrial ecosystems release greenhouse gases (GHGs) (i.e. carbon dioxide (CO 2 ),
methane, and nitrous oxide) and act as a sink when storing carbon (C) in vegetation
and soil [4]. As levels of CO 2 and other GHGs in the atmosphere have been increasing, rising concern over the impact of these gases on world climate systems has
been elevated which led to increasing the awareness towards the global carbon cycle.
Therefore, international negotiations are held for reducing GHGs level in the atmosphere [8]. The actions for mitigating GHGs impacts increased with the adoption of
United Nations Framework Convention on Climate Change (UNFCCC) in 1992 and
the Kyoto Protocol in 1997. The prime objective of this convention is to stabilize the
level of greenhouse gases at the level that would not cause further damage; especially
anthropologically; to the climate system [9].
An estimated emission of GHGs from agriculture, forestry and land-use is approximately 24% (concentrated mainly in mainly CH 4 and N 2 O of total global atmospheric
emissions of GHGs [10]. Global cultivated soils are estimated to release about 50
Pg C into the atmosphere via mineralization of SOC [11]. Although soil is the main
terrestrial organic carbon (OC) stock, representing 75% of the Earth’s terrestrial OC,
it can act as a sink or a source of carbon and atmospheric CO 2 with direct influence
on the greenhouse effect [12].
Available data indicate that, managed soils have historically been a net source
of atmospheric CO 2 contributing to more than 20% of the annual increase of CO 2 ;
3.2 Pg C in the atmosphere, however, soils can be a net sink for C through enhancement of long-term C storage or sequestration in the soils and thus reduction in CO 2
accumulation rate in the atmosphere [6]. Therefore, measurement of CO 2 flux has
been considered as a reliable and sensitive indicator of C cycling in response to soil
management practices [13]. There are many factors affecting the rate of CO 2 flux
from agricultural soils and these factors vary temporally and regionally. These factors are representing in management practices (such as the addition of exogenous
organic inputs, quantity and quality of litter inputs), environmental conditions (i.e.
temperature and soil moisture) and the soil microbial community. It is reported soil