Soil Carbon Sequestration for Climate Change Mitigation …
171
data analyzed after sampling from this area [Fig. 1 in 2007, while the estimated
data are calculated based on regression equation of actual values of soil C and N
and the values of Normalized Difference Vegetation Index (NDVI)]. The NDVI was
calculated based on different landscape images in different time intervals (i.e. 1987,
1990 and 1998). The rate of C and N sequestration according to the equation of
sequestration rate as described by [51, 91]. It is noticed from this study that there
were a declining in C and N contents in some sampling locations, however, there are
an increment in other sampling locations in north Nile delta which means that those
sites represented sink of atmospheric C or N emissions (i.e. other profiles consider
the source of CO 2 emission to the atmosphere). These data are presented in Table 1.
It is observed from Elbasiouny [81] that some profiles especially 10 and 11 in all
cases (i.e. SOCS, SICS, TSCS and TSNS) are positive which means that those profiles
represented a sink for C or N emissions in the atmosphere (i.e. other profiles consider
the source of CO 2 emission to the atmosphere). Those profiles were cultivated by
rice and may be this the reason for positivity of sequestration rate of soil C and N in
them. However, there are some observations, where in SOCS; profiles 6 and 12 are
sinks not sources of CO 2 . Hou et al. [66] reported that since SOC is crucial affecting
soil physical, chemical, and biological properties, more SOC sequestration in the
soil can assist in sustaining soil fertility and agronomic productivity. Jacinthe et al.
[6] showed that taking the forest soil as a reference for SOM data, the data revealed
SOM depletion in the cultivated soils and SOM enrichment in the depositional areas.
The SOC inventory (0–30 cm) in the drained and undrained cultivated fields was
5.6 and 6.0 kg C m
−2 , respectively representing 72–77% of the original SOC stock
(forest: 7.9 kg C m
−2 ). These data can be translated into a total SOC depletion of 2.2
and 1.8 kg C m
−2 in the drained and undrained croplands, respectively. However;
Alvarez et al. [92] found a negative C balance in their studied soil of the Rolling
Pampa. Consequently, a net loss of C from the soil is apparently in progress. Chung
et al. [93] stated that evidence has confirmed approximately 40–70% of OC in the
active soil layer (1.0 m topsoil layer) was lost in nearly 50 years. Most of this
loss recorded in the first 25 years, as carbon emission showed an almost exponential
decline with time year. Therefore, the 25-year timescale is generally used to calculate
the current carbon emission produced by land-use change.
On the other hand; the lowest negative sequestration rate in SICS was (−19.33
Mg ha
−1 year
−1 ), while the highest is recorded as (20.34 Mg ha
−1 year
−1 ) as presented
in Table 1. It is also observed that SIC represent a sink of C in some profiles as
recorded in the previous table. Mei et al. [94] mentioned that although the role
of SIC in C sequestration is less well understood, depending on the site-specific
conditions, SIC may act as a sink or source or have no effect upon C sequestration.
Lal [95] reported the additional potential for C sequestration beside SOC through
SIC sequestration. Moreover, the emphasis on existing a strong correlation between
net NPP and formation of secondary carbonates, and between SOC and secondary
carbonates. The rate of formation of secondary carbonates depends on the rainfall
and quality of irrigation water. For SIC sequestration rate of 20–400 kg ha
−1 year
−1
over 344 Mha of arid and semiarid soils, total potential of SIC sequestration is
7–138 Tg C year
−1 .
171
data analyzed after sampling from this area [Fig. 1 in 2007, while the estimated
data are calculated based on regression equation of actual values of soil C and N
and the values of Normalized Difference Vegetation Index (NDVI)]. The NDVI was
calculated based on different landscape images in different time intervals (i.e. 1987,
1990 and 1998). The rate of C and N sequestration according to the equation of
sequestration rate as described by [51, 91]. It is noticed from this study that there
were a declining in C and N contents in some sampling locations, however, there are
an increment in other sampling locations in north Nile delta which means that those
sites represented sink of atmospheric C or N emissions (i.e. other profiles consider
the source of CO 2 emission to the atmosphere). These data are presented in Table 1.
It is observed from Elbasiouny [81] that some profiles especially 10 and 11 in all
cases (i.e. SOCS, SICS, TSCS and TSNS) are positive which means that those profiles
represented a sink for C or N emissions in the atmosphere (i.e. other profiles consider
the source of CO 2 emission to the atmosphere). Those profiles were cultivated by
rice and may be this the reason for positivity of sequestration rate of soil C and N in
them. However, there are some observations, where in SOCS; profiles 6 and 12 are
sinks not sources of CO 2 . Hou et al. [66] reported that since SOC is crucial affecting
soil physical, chemical, and biological properties, more SOC sequestration in the
soil can assist in sustaining soil fertility and agronomic productivity. Jacinthe et al.
[6] showed that taking the forest soil as a reference for SOM data, the data revealed
SOM depletion in the cultivated soils and SOM enrichment in the depositional areas.
The SOC inventory (0–30 cm) in the drained and undrained cultivated fields was
5.6 and 6.0 kg C m
−2 , respectively representing 72–77% of the original SOC stock
(forest: 7.9 kg C m
−2 ). These data can be translated into a total SOC depletion of 2.2
and 1.8 kg C m
−2 in the drained and undrained croplands, respectively. However;
Alvarez et al. [92] found a negative C balance in their studied soil of the Rolling
Pampa. Consequently, a net loss of C from the soil is apparently in progress. Chung
et al. [93] stated that evidence has confirmed approximately 40–70% of OC in the
active soil layer (1.0 m topsoil layer) was lost in nearly 50 years. Most of this
loss recorded in the first 25 years, as carbon emission showed an almost exponential
decline with time year. Therefore, the 25-year timescale is generally used to calculate
the current carbon emission produced by land-use change.
On the other hand; the lowest negative sequestration rate in SICS was (−19.33
Mg ha
−1 year
−1 ), while the highest is recorded as (20.34 Mg ha
−1 year
−1 ) as presented
in Table 1. It is also observed that SIC represent a sink of C in some profiles as
recorded in the previous table. Mei et al. [94] mentioned that although the role
of SIC in C sequestration is less well understood, depending on the site-specific
conditions, SIC may act as a sink or source or have no effect upon C sequestration.
Lal [95] reported the additional potential for C sequestration beside SOC through
SIC sequestration. Moreover, the emphasis on existing a strong correlation between
net NPP and formation of secondary carbonates, and between SOC and secondary
carbonates. The rate of formation of secondary carbonates depends on the rainfall
and quality of irrigation water. For SIC sequestration rate of 20–400 kg ha
−1 year
−1
over 344 Mha of arid and semiarid soils, total potential of SIC sequestration is
7–138 Tg C year
−1 .