Agriculture Reference
In-Depth Information
world is confounded by the fundamental complexity arising on account of
interplay of set of dynamic factors specific to each citrus belt. Experimen-
tal studies of the long-term effects of CO
2
in more realistic field settings
have not yet been done on a comprehensive scale (Rosenzweig and Hillel,
1993).
In high-N ecosystem, the maximum amount of C that can be decom-
posed may be less than in low-N ecosystem, resulting in greater C storage
in high N ecosystem (De Deyn et al., 2008), Similarly, atmospheric depo-
sition of N can retard rates of soil organic matter (SOM) decomposition
by reducing the production of lignolytic and cellulolytic soil enzymes;
however, the effect of enhanced soil fertility on decomposition processes
may be ecosystem specific (Waldrop et al., 2004). Differences in C seques-
tration responses to N addition may depend on whether the largest effect
of N in soils is to increase nonbiological formation of recalcitrant soil
organic matter (reducing decomposability) or to increase the growth and
metabolism of soil decomposers (N stimulation of decomposition).
It is contemplated that global warming may significantly alter soil
composition at the molecular level, and that such changes could have a
major impact on atmospheric levels of CO
2
. Global warming may change
present day decomposition patterns by altering the soil microbial commu-
nities and activities, thus changing the overall flow of carbon into and out
of the soil, and affecting the soil fertility as well. The implication of the
increased degradation of lignins is that less carbon remains in soil solid
phase, and more CO
2
is released from soil into the atmosphere (Lance
Frazer, 2009). To understand the soil-climate interactions better, we need
more soil research to focus the molecular level within an eye toward pre-
dicting both short- and long-range changes in system. In this context, the
studies pertaining to changes in nutrient pool of citrus rhizosphere, mi-
crobial communities and soil carbon partitioning are highly imperative in
response to elevated CO
2
and temperature.
11.5
CLIMATE VERSUS SOIL MICROBIAL DYNAMICS
Soils are of particular importance in atmospheric CO
2
budget for number
of reasons. At the global scale, rates of soil CO
2
efflux correlated signifi-
cantly with temperature and precipitation, however, did not correlate well
