Impacts of Climate Change on Microbial Activity in Agricultural …
105
that soil basal respiration was significantly increased by 14%, while the metabolic
quotient for CO 2 (qCO 2 ) (basal respiration/microbial C) was not statistically significant differences by elevated CO 2 treatments. Microbial biomass C and soil organic
C and N were not significantly affected by elevated CO 2 , and microbial biomass N
increased by 18%. According to Dijkstra et al. [56], elevated CO 2 increased labile
C and microbial biomass, but had no effect on net N mineralization, respiration of
more recalcitrant C, or total soil C and N.
The previous literature indicate that in many systems exposed to elevated CO 2 ,
mycorrhizal fungi can be sequestering the large amount from C in living, dead, and
residual hyphal biomass in soil [57]. Increasing CO 2 had a positive effect on the
populations of endo/or ectomycorrhizal fungi, while the effect of elevated CO 2 on
plant growth promoting bacteria and endophytic fungi were more variable (Positive, neutral or negative) based on the study conditions. In general, plant-associated
microorganisms had a positive or beneficial effect on the plant under elevated CO 2
[34]. Extraradical hyphae and percentage root length colonized in AM fungi in a manner proportional to the plant response under elevated CO 2 increased [58]. Increased
atmospheric CO 2 concentration is much more affected by the rhizosphere zone than
the bulk soil. The production CO 2 in the rhizosphere by soil microorganisms and plant
roots is promoted by elevated CO 2 concentration and may be higher than the increase
in root biomass [59]. Previous studies indicated that the abundance of arbuscular and
ectomycorrhizal fungi in the rhizosphere had a positive response to elevated CO 2 ,
whereas plant growth-promoting bacteria and endophytic fungi have so susceptible
response to elevated CO 2 . Additionally, beneficial effect on plant growth due to use
plant-associated microorganisms will increase under elevated CO 2 [34]. The growth
of mycorrhizae on plants have been positively or negatively response to elevated CO 2
concentration, and these responses are varied based on the differences in plant and
fungal species under investigation.
Increased CO 2 attributed to the increase in soil respiration can have a potentially negative impact on soil C sequestration, but increased atmospheric CO 2 led to
an increasingly global ecosystem C storage [59]. Previous studies investigated the
potential of C storage of reclaimed soils under organic management. For instance,
Luske and van der Kamp [60] investigated the potential of C storage of reclaimed
desert soils in Egypt under two organic farms owned by Sekem (1–30 years in use).
They showed that the reclaimed desert soils sequester C very quickly in the first few
years after land reclamation. However, the rate of C sequestration is decreased after
several years. Soil C storage increased from 3.9 to 28.8–31.8 tons C ha
−1 in 30 years
of organic agriculture. The effect of short (2030), medium (2050) and long-term
(2100) climate change on soil organic carbon stock was studied by Muñoz-Rojas
et al. [61] at different soil depths in a Mediterranean arid area (El-Fayoum, Northern
Egypt) for different land use type. The result demonstrated that the evaluation of soil
organic C contents and dynamics lengthways the soil profile and the potential for
soil C sequestration, especially in the subsoil.
105
that soil basal respiration was significantly increased by 14%, while the metabolic
quotient for CO 2 (qCO 2 ) (basal respiration/microbial C) was not statistically significant differences by elevated CO 2 treatments. Microbial biomass C and soil organic
C and N were not significantly affected by elevated CO 2 , and microbial biomass N
increased by 18%. According to Dijkstra et al. [56], elevated CO 2 increased labile
C and microbial biomass, but had no effect on net N mineralization, respiration of
more recalcitrant C, or total soil C and N.
The previous literature indicate that in many systems exposed to elevated CO 2 ,
mycorrhizal fungi can be sequestering the large amount from C in living, dead, and
residual hyphal biomass in soil [57]. Increasing CO 2 had a positive effect on the
populations of endo/or ectomycorrhizal fungi, while the effect of elevated CO 2 on
plant growth promoting bacteria and endophytic fungi were more variable (Positive, neutral or negative) based on the study conditions. In general, plant-associated
microorganisms had a positive or beneficial effect on the plant under elevated CO 2
[34]. Extraradical hyphae and percentage root length colonized in AM fungi in a manner proportional to the plant response under elevated CO 2 increased [58]. Increased
atmospheric CO 2 concentration is much more affected by the rhizosphere zone than
the bulk soil. The production CO 2 in the rhizosphere by soil microorganisms and plant
roots is promoted by elevated CO 2 concentration and may be higher than the increase
in root biomass [59]. Previous studies indicated that the abundance of arbuscular and
ectomycorrhizal fungi in the rhizosphere had a positive response to elevated CO 2 ,
whereas plant growth-promoting bacteria and endophytic fungi have so susceptible
response to elevated CO 2 . Additionally, beneficial effect on plant growth due to use
plant-associated microorganisms will increase under elevated CO 2 [34]. The growth
of mycorrhizae on plants have been positively or negatively response to elevated CO 2
concentration, and these responses are varied based on the differences in plant and
fungal species under investigation.
Increased CO 2 attributed to the increase in soil respiration can have a potentially negative impact on soil C sequestration, but increased atmospheric CO 2 led to
an increasingly global ecosystem C storage [59]. Previous studies investigated the
potential of C storage of reclaimed soils under organic management. For instance,
Luske and van der Kamp [60] investigated the potential of C storage of reclaimed
desert soils in Egypt under two organic farms owned by Sekem (1–30 years in use).
They showed that the reclaimed desert soils sequester C very quickly in the first few
years after land reclamation. However, the rate of C sequestration is decreased after
several years. Soil C storage increased from 3.9 to 28.8–31.8 tons C ha
−1 in 30 years
of organic agriculture. The effect of short (2030), medium (2050) and long-term
(2100) climate change on soil organic carbon stock was studied by Muñoz-Rojas
et al. [61] at different soil depths in a Mediterranean arid area (El-Fayoum, Northern
Egypt) for different land use type. The result demonstrated that the evaluation of soil
organic C contents and dynamics lengthways the soil profile and the potential for
soil C sequestration, especially in the subsoil.