Agriculture Reference
In-Depth Information
enhAncIng the soIl oRgAnIc mAtteR Pool
Depletion of the SOM pool is an important process that sets in motion other deg-
radation processes. In corollary, therefore, restoring the SOM pool is essential to
improving soil structure, increasing the plant-available water capacity, reducing
erodibility and decreasing risks of soil erosion and non-point source pollution,
improving elemental cycling, and enhancing soil biodiversity (Figure 18.2). At a
global scale, increasing the SOM pool has synergistic effects on achieving/advanc-
ing food security (Lal 2006), mitigating climate change (Lal 2004), and improving
the water resources.
The SOM pool is an integral component of the terrestrial carbon pool (TCP) in
the biosphere (Batjes 1996). Different components of the TCP include the carbon
pool in the world's soils, forests, and wetlands (Figure 18.3). The soil carbon pool
includes SOC and soil inorganic carbon (SIC) components. It is the transformation of
the SOC pool from labile and dissolved fractions into stable humic substances and of
precipitation of dissolved bicarbonates and carbonic acids into secondary carbonates
that lead to stabilization/protection of the soil carbon pool. The forest/biotic carbon
pool is comprised of these items and below-ground biomass and the detritus mate-
rial. The depth distribution of the below-ground biomass and the relative abundance
of recalcitrant substances (e.g., lignin, seubrin, phenols) are important to stabiliza-
Improves soil structure
Increases plant available water
capacity
• Advances Food
Security
• Mitigates Climate
Change
• Improves Water
Resources
Enhancing SOM
Pool
Reduces soil erosion and non
point source pollution
Strengthens elemental cycling
and soil fertility
Enhances soil biodiversity and
microbial biomass pool
fIguRe 18.2
Interactive effects of enhancing soil organic matter (SOM) pool on global
food security and mitigating climate change.
