Agriculture Reference
In-Depth Information
The present citrus production trends are characterized by either frequent
crop failure or recurrence of alternate on-and-off years, setting unaccount-
able monetary loss to the industry (Rojas, 1998). In recent years, nutrient
additions have been exclusively in favor of mineral fertilizers due to de-
mographic pressure, demands related to life styles and trade involvement.
While the quick and substantial response to fruit yield due to mineral fertil-
izers eclipsed the use of organic manures, the inadequate supply of the latter
sources exacerbated this change (Srivastava and Ngullie, 2009; Srivastava,
2009). Differential efficacy of two conventional methods of fertilization
(soil versus foliar application) has, although helped in improving the qual-
ity citrus, but of late, continuous fertilization has failed to sustain the same
yield expectancy on a long-term basis due to depletion of soil carbon stock
and consequently, emerged multiple nutrient deficiencies, irrespective of
soil type. The menace of multiple nutrient deficiencies is further triggered
through increase in air temperature via changes in microbial communities
and activities within the rhizosphere in the light of climate change. Such
changes will dictate adversely on the orchard's productive life in long run.
Gradual shift from purely inorganic to organic fertilizers started gaining
wide scale use for enhanced nutrient cycling (Srivastava et al., 2002).
Integrated Nutrient Management (INM) as a dynamic concept of nu-
trient management considers the economic yield in terms of fruit yield
coupled with quality on one hand, and soil physicochemical and microbial
prospects on other hand as a marker of resistance against the nutrient min-
ing (arises because of failure to strike a balance between annual nutrient
demand versus the quantity of nutrients applied). Soils under citrus differ
from other cultivated soils, which remain fallow for 3-6 months every
year forcing depletion of SOM (Bhargava, 2002). In contrast, biological
oxidation of existing C continues in soil covered under citrus (Srivastava
et al., 2002). Multiple nutrient deficiencies are considered to have a trig-
gering effect on potential source of atmospheric CO
2
. Soil carbon stock
is considered as an important criterion to determine the impact of INM in
the longer version of impact assessment (He et al., 1997). The amount of
accumulated C within the rhizosphere soil does not continue to increase
with time with increasing C outputs. An upper limit of C saturation level
occurs, which governs the ultimate limit of soil C sink and rate of C se-
questration in mineral soils, independent of C input rate. An understanding
of the mechanism involved in C stabilization in soils is needed for control-
