Agriculture Reference
In-Depth Information
ling and enhancing soil C sequestration (Goh, 2004) under varying modes
of nutrient management.
11.7.5 SOIL MICROBIAL POPULATION
An increase in the microbial biomass often goes along with increased nu-
trient immobilization. Over the years, the concepts of INM and integrated
soil management (ISM) have been gaining acceptance, moving away from
a more sectoral and inputs driven approach. INM advocates the careful
management of nutrient stocks and flows in a way that leads to profitable
and sustained production. ISM emphasizes the management of nutrient
flows, but also highlights other important aspects of soil complex such as
maintaining organic matter content, soil structure, moisture, and microbial
biodiversity. Still more attention is needed towards integrated soil bio-
logical management as a crucial aspect of soil fertility management since
providing protection to citrus rhizosphere against the nutrient depletion is
of utmost importance for sustained orchard production in which the objec-
tivity of INM could have far reaching consequences.
In our studies, the soil microbial count in terms of bacterial and fun-
gal count showed
significant changes in response to different INM-based
treatments
(
Table 11.7
).
Bacterial and fungal counts both reduced to 31
and 16 × 10
3
cfu g
-1
, respectively, with T
2
incorporating MC with 75%
RDF from corresponding values of 32 and 16 × 10
3
cfu g
-1
with T
1
hav-
ing 100% RDF as inorganic fertilizers supporting the fact that as long as
good soil productivity is obtained, soil microbial health could be main-
tained even with inorganic fertilizers. Of course, the magnitude of such
response will be of comparatively lower order when compared with or-
ganic manures or in combination with inorganic fertilizers plus microbial
biofertilizers. Out of two organic manures (FYM versus vermicompost),
vermicompost based treatments produced much favorable response on soil
microbial counts as evident from superiority of T
7
(50 and 25 cfu g
-1
bacte-
rial and fungal counts, respectively) over T
3
(45 and 19 × 10
3
cfu g
-1
bac-
terial and fungal counts, respectively). Similarly treatment T
8
(53 and 26
× 10
3
cfu g
-1
bacterial and fungal counts, respectively) was better than T
4
(44 and 20 × M module as T
9(
68 and 41 × 10
3
cfu g
-1
bacterial and fungal
counts, respectively) supporting much better soil microbial counts com-
pared to FYM-based INM as T
5
(57 and 25 ×10
3
cfu g
-1
bacterial and fungal
