Soil Carbon Sequestration for Climate Change Mitigation …
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factor that determines the size and kinetic of SOC stock because of its influencing
on the balance between SOC inputs (e.g. plant litter) and outputs (e.g. mineralization of SOC) by altering plant community and land management practice [30]. Also,
optimizing agricultural management practices are very important factors that can
increase C inputs and decrease C outputs such as fertilizer application, straw-return,
or conservation tillage [25]. The impact of topographic aspect on SOC is widely
realized. However, relatively few studies have been conducted to examine its role on
SOC contents globally [26].
7.1 Soil Properties
Soil parent material can have a major impact on the functions of ecosystem vegetation
and soil, hence deeply influence SOM stock. Soil parent material has been noticed
to be an important factor affecting regional SOC and soil N stocks [55]. Young
and Spycher [56] found that C levels increased with decreasing particle size. Heavy
textured soils had a larger C storage capacity than those with a light texture, which
had already attained their estimated capacity [24]. Thus, the properties of coarse
textured soils such as low clay content and a shortage of water-stable aggregation are
major factors that limit the C and N storage capacity [57]. Zhang et al. [28] as well,
emphasized on the favorability of SOC accumulation in soils with finer particles are
favorable and attributed that to the stronger adsorption ability of soil clay and silt
to SOC. The protective effect of soil clay on OM involves the interaction of OM
with the surface of the clay particles (cation bridges, hydrogen bonds, electrostatic
and van der Waals interactions) and the occlusion of organic material in the matrix
of soil aggregates [58]. Nelson et al. [59] mentioned that clay with its high surface
area protects OC from decomposition on developing stable clay-organic complexes.
However, such a relationship between clays and OC does not always occur. Bot and
Benites [60] mentioned that SOM tends to increase as the clay content increases. This
increase relies on two mechanisms; (1) bonds between the surface of clay particles
and OM retard the decomposition process and (2) soils with higher clay content
increase the capacity for aggregate formation. Macroaggregates physically protect
OM molecules from further mineralization caused by the microbial attack. They also
mentioned that in similar climate conditions, the OM content in clayey soils ranges
from 2 to 4 times its corresponding of sandy soils.
Soil aggregation as well have a great influence on the physical characteristics of
the soil. Well-aggregated soils provide a larger pore space, a higher infiltration rate
and better gaseous exchange between soil and atmosphere than poorly aggregated
soils, resulting in enhanced microbial activity. Soil aggregation and SOM dynamics
are largely linked. Each of aggregates and SOM plays an important role for the
other. SOM thought to be physically protected within aggregates and at the same
time, aggregates are formed by binding SOM with mineral particles to form of
161
factor that determines the size and kinetic of SOC stock because of its influencing
on the balance between SOC inputs (e.g. plant litter) and outputs (e.g. mineralization of SOC) by altering plant community and land management practice [30]. Also,
optimizing agricultural management practices are very important factors that can
increase C inputs and decrease C outputs such as fertilizer application, straw-return,
or conservation tillage [25]. The impact of topographic aspect on SOC is widely
realized. However, relatively few studies have been conducted to examine its role on
SOC contents globally [26].
7.1 Soil Properties
Soil parent material can have a major impact on the functions of ecosystem vegetation
and soil, hence deeply influence SOM stock. Soil parent material has been noticed
to be an important factor affecting regional SOC and soil N stocks [55]. Young
and Spycher [56] found that C levels increased with decreasing particle size. Heavy
textured soils had a larger C storage capacity than those with a light texture, which
had already attained their estimated capacity [24]. Thus, the properties of coarse
textured soils such as low clay content and a shortage of water-stable aggregation are
major factors that limit the C and N storage capacity [57]. Zhang et al. [28] as well,
emphasized on the favorability of SOC accumulation in soils with finer particles are
favorable and attributed that to the stronger adsorption ability of soil clay and silt
to SOC. The protective effect of soil clay on OM involves the interaction of OM
with the surface of the clay particles (cation bridges, hydrogen bonds, electrostatic
and van der Waals interactions) and the occlusion of organic material in the matrix
of soil aggregates [58]. Nelson et al. [59] mentioned that clay with its high surface
area protects OC from decomposition on developing stable clay-organic complexes.
However, such a relationship between clays and OC does not always occur. Bot and
Benites [60] mentioned that SOM tends to increase as the clay content increases. This
increase relies on two mechanisms; (1) bonds between the surface of clay particles
and OM retard the decomposition process and (2) soils with higher clay content
increase the capacity for aggregate formation. Macroaggregates physically protect
OM molecules from further mineralization caused by the microbial attack. They also
mentioned that in similar climate conditions, the OM content in clayey soils ranges
from 2 to 4 times its corresponding of sandy soils.
Soil aggregation as well have a great influence on the physical characteristics of
the soil. Well-aggregated soils provide a larger pore space, a higher infiltration rate
and better gaseous exchange between soil and atmosphere than poorly aggregated
soils, resulting in enhanced microbial activity. Soil aggregation and SOM dynamics
are largely linked. Each of aggregates and SOM plays an important role for the
other. SOM thought to be physically protected within aggregates and at the same
time, aggregates are formed by binding SOM with mineral particles to form of