154
H. Elbasiouny and F. Elbehiry
respiration as a main source of CO 2 released from the soil; it changes with different
climatic conditions, ecosystem type and SOC concentration [14]. Moreover, it is
reported that a substantial amount of total global CO 2 emission comes from the soil
through mineralization and OM decomposition, and roots and organism respiration
in the soil. Therefore, even a small change in the flux of soil CO 2 can greatly influence atmospheric CO 2 levels [13]. In addition, it is stated that in agriculture, CO 2
is released by (1) decomposition of crop residues and SOC, which is enhanced by
intense tillage practices, (2) production and application of crop inputs, (3) using fossil
fuels directly in farm machinery, and (4) burning or oxidation of biomass. The only
process of CO 2 uptake is photosynthesis, and the only stock that can sequester C is
the soil. Subsequently, net carbon emission indicates loss of CO 2 from biomass and
soil to the atmosphere through decomposition or combustion. Net carbon removal
or sequestration indicates net CO 2 uptake and storage in biomass and soil [1, 15].
Hence, soil can serve as a source or sink for atmospheric CO 2 depending on the
agricultural management practices employed [13].
3 Soil Carbon Sequestration for Climate Change
Mitigation and Greenhouse Gases Reduction
The effects of land use changes on SOC stocks are a matter of concern in international
policy agendas on greenhouse emissions mitigation [12]. There are two potential
measures to balance global C cycle; either cut the emission rate of CO 2 and/or to
develop natural C sink that can absorb the increasing level of CO 2 . Increasing forest
areas can be a sustainable way to mitigate elevated atmospheric CO 2 concentration
[14]. Sequestration of SOC, as a key tool of the strategy of climate change mitigation,
is ideal in natural ecosystems that have high plant primary productivity and low
SOC decomposition [16]. Also, since the United Nations Framework Convention on
Climate Change, there has been increasing interest in afforestation to sequester CO 2
from the atmosphere. More attention is paid to environmental restoration of land use
change by afforestation as an appropriate prescription and one of the most currently
effective and applicable carbon sequestration strategies. As well, the role of soils in
the sequestration of SOC is so crucial that the Kyoto Protocol (article 3.3) and the
Paris agreement involved it as an important portion for managing [12].
The dynamics of SOC stocks and the role that the soil may play in the long-term
storage and sequestration of atmospheric CO 2 are of great concern not only because
of their impacts on climate change mitigation, but also the sustainability of crop productivity, and soil fertility [17]. Although cultivation has resulted in considerable loss
of soil C due to chemical and biological decomposition of SOC, in carefully managed croplands, soil C sequestration can be substantial and represents a potentially
constructive measure for mitigating the increased levels of atmospheric CO 2 [18].
There is a general agreement that many agricultural ecosystems have the potential
to sequester more carbon in their soil [15]. CO 2 sequestered in the soils is slowly
H. Elbasiouny and F. Elbehiry
respiration as a main source of CO 2 released from the soil; it changes with different
climatic conditions, ecosystem type and SOC concentration [14]. Moreover, it is
reported that a substantial amount of total global CO 2 emission comes from the soil
through mineralization and OM decomposition, and roots and organism respiration
in the soil. Therefore, even a small change in the flux of soil CO 2 can greatly influence atmospheric CO 2 levels [13]. In addition, it is stated that in agriculture, CO 2
is released by (1) decomposition of crop residues and SOC, which is enhanced by
intense tillage practices, (2) production and application of crop inputs, (3) using fossil
fuels directly in farm machinery, and (4) burning or oxidation of biomass. The only
process of CO 2 uptake is photosynthesis, and the only stock that can sequester C is
the soil. Subsequently, net carbon emission indicates loss of CO 2 from biomass and
soil to the atmosphere through decomposition or combustion. Net carbon removal
or sequestration indicates net CO 2 uptake and storage in biomass and soil [1, 15].
Hence, soil can serve as a source or sink for atmospheric CO 2 depending on the
agricultural management practices employed [13].
3 Soil Carbon Sequestration for Climate Change
Mitigation and Greenhouse Gases Reduction
The effects of land use changes on SOC stocks are a matter of concern in international
policy agendas on greenhouse emissions mitigation [12]. There are two potential
measures to balance global C cycle; either cut the emission rate of CO 2 and/or to
develop natural C sink that can absorb the increasing level of CO 2 . Increasing forest
areas can be a sustainable way to mitigate elevated atmospheric CO 2 concentration
[14]. Sequestration of SOC, as a key tool of the strategy of climate change mitigation,
is ideal in natural ecosystems that have high plant primary productivity and low
SOC decomposition [16]. Also, since the United Nations Framework Convention on
Climate Change, there has been increasing interest in afforestation to sequester CO 2
from the atmosphere. More attention is paid to environmental restoration of land use
change by afforestation as an appropriate prescription and one of the most currently
effective and applicable carbon sequestration strategies. As well, the role of soils in
the sequestration of SOC is so crucial that the Kyoto Protocol (article 3.3) and the
Paris agreement involved it as an important portion for managing [12].
The dynamics of SOC stocks and the role that the soil may play in the long-term
storage and sequestration of atmospheric CO 2 are of great concern not only because
of their impacts on climate change mitigation, but also the sustainability of crop productivity, and soil fertility [17]. Although cultivation has resulted in considerable loss
of soil C due to chemical and biological decomposition of SOC, in carefully managed croplands, soil C sequestration can be substantial and represents a potentially
constructive measure for mitigating the increased levels of atmospheric CO 2 [18].
There is a general agreement that many agricultural ecosystems have the potential
to sequester more carbon in their soil [15]. CO 2 sequestered in the soils is slowly