47
(f) Regulating various processes underlying the supply of nutrients, hence creating
a favorable environment for plant growth.
(g) Regulating various processes governing the creation of soil-based ecosystem
services.
(h) Buffering against sudden fluctuations in soil reaction (pH) due to the application of agricultural chemicals.
(i) Moderating soil temperature through its effect on soil color and albedo.
(j) Reducing sediment load in streams and rivers.
(k) Filtering pollutants of agricultural chemicals, as well as complexing and immobilizing metals.
(l) Buffering the emissions of greenhouse gases (GHGs) from soil to the
atmosphere.
It is obvious from the above functions that SOC is a key indicator of ecosystem
health and productivity; therefore, conserving, restoring, and enhancing SOC concentration to above the threshold level of 1.5–2% is a critical determinant of food
and nutritional security worldwide.
2.4 Soil C Sequestration
When land is converted from native ecosystems to agro-ecosystems, the SOC pool
gets depleted if it is not managed sustainably. This is because the bulk of the crop
biomass is usually removed from the fields after harvest for use as food or fuel. Only
a small amount of readily decomposable residues remain on the fields to accumulate
SOM. Removal of crop biomass also aggravates the degradation processes (i.e., erosion) initiated by the land use changes. In addition, frequent tillage and other perturbations disintegrate soil aggregates, redistribute crop residues, and alter soil aeration,
moisture, and temperature. This accelerates microbial decomposition and the oxidation of SOM to CO 2 , which is ultimately emitted to the atmosphere (Were et al. 2015).
Restoration of the SOC pool and concomitant ecosystem services can only be
achieved when more SOM is gained than lost through the process of C sequestration. Soil C sequestration per se is the uptake and conversion of atmospheric CO 2 to
organic matter through photosynthesis by plants and the subsequent transfer of the
organic matter into the soil reservoir for storage in a way that prolongs its mean residence time (Lal et al. 2015) (Fig. 2). SOC sequestration affords double wins because
it restores ecosystem services, which stimulate productive and stable agroecosystems, and curbs the emission of GHGs, which contribute to climate change.
Lal (2014) argued that an effective soil C sequestration strategy should create a
positive ecosystem C budget through (i) increasing the soil application of biomass
C, (ii) decreasing losses of SOC by soil erosion, (iii) moderating soil temperature
and reducing the rates of mineralization, and (iv) enhancing the MRTs of SOC by
increasing soil aggregation and stability (Fig. 3).
Land Use Changes and Sustainable Land Management Practices for Soil Carbon…
(f) Regulating various processes underlying the supply of nutrients, hence creating
a favorable environment for plant growth.
(g) Regulating various processes governing the creation of soil-based ecosystem
services.
(h) Buffering against sudden fluctuations in soil reaction (pH) due to the application of agricultural chemicals.
(i) Moderating soil temperature through its effect on soil color and albedo.
(j) Reducing sediment load in streams and rivers.
(k) Filtering pollutants of agricultural chemicals, as well as complexing and immobilizing metals.
(l) Buffering the emissions of greenhouse gases (GHGs) from soil to the
atmosphere.
It is obvious from the above functions that SOC is a key indicator of ecosystem
health and productivity; therefore, conserving, restoring, and enhancing SOC concentration to above the threshold level of 1.5–2% is a critical determinant of food
and nutritional security worldwide.
2.4 Soil C Sequestration
When land is converted from native ecosystems to agro-ecosystems, the SOC pool
gets depleted if it is not managed sustainably. This is because the bulk of the crop
biomass is usually removed from the fields after harvest for use as food or fuel. Only
a small amount of readily decomposable residues remain on the fields to accumulate
SOM. Removal of crop biomass also aggravates the degradation processes (i.e., erosion) initiated by the land use changes. In addition, frequent tillage and other perturbations disintegrate soil aggregates, redistribute crop residues, and alter soil aeration,
moisture, and temperature. This accelerates microbial decomposition and the oxidation of SOM to CO 2 , which is ultimately emitted to the atmosphere (Were et al. 2015).
Restoration of the SOC pool and concomitant ecosystem services can only be
achieved when more SOM is gained than lost through the process of C sequestration. Soil C sequestration per se is the uptake and conversion of atmospheric CO 2 to
organic matter through photosynthesis by plants and the subsequent transfer of the
organic matter into the soil reservoir for storage in a way that prolongs its mean residence time (Lal et al. 2015) (Fig. 2). SOC sequestration affords double wins because
it restores ecosystem services, which stimulate productive and stable agroecosystems, and curbs the emission of GHGs, which contribute to climate change.
Lal (2014) argued that an effective soil C sequestration strategy should create a
positive ecosystem C budget through (i) increasing the soil application of biomass
C, (ii) decreasing losses of SOC by soil erosion, (iii) moderating soil temperature
and reducing the rates of mineralization, and (iv) enhancing the MRTs of SOC by
increasing soil aggregation and stability (Fig. 3).
Land Use Changes and Sustainable Land Management Practices for Soil Carbon…