Abstract:
The forest ecosystems provide critical and diverse services and values to
human society. As primary habitat for wide range of species, forests support
biodiversity maintenance and conservation. We cannot understand about forest
without the knowledge of forest soil. Therefore, the main objective of this
study is to study about the physical, chemical and microbiological properties
of soil of Panchakanya forest and its surrounding area. 30 soil samples from 5
different locations of Panchakanya forest and 5 different locations surrounding
Panchakanya forest were collected and analyzed for physical properties
(moisture content, water holding capacity, pH, bulk density, electric
conductivity), soil texture (sand, silt and clay) and chemical properties
(carbon, nitrogen, potassium, phosphorus, soil microbial biomass carbon and
soil microbial biomass nitrogen). Total plate count was done to study about
the microbial load of each sample. Different species of Azotobacter was
isolated and identified according to Bergey’s Manual of Systematic
Bacteriology. To establish the correlation between the physico-chemical
variables and organism, the canonical analysis (CA) was performed.
Most of the soil samples were loamy sand having mean moisture content of
24.33%, mean water holding capacity of 60.5% mean bulk density of 1.24
gm/cm3
and mean electric conductivity of 0.246mS/cm. Most of the soil
samples were slightly acidic to neutral. The value of mean soil nitrogen was
0.1016%, organic carbon was 1.99%, mean phosphorus content was
2.278mg/l, mean potassium content was 44.85ppm, mean SMBC was 808.75
mg/kg and mean SMBN was 16.108 mg/kg. The value of total plate count
ranged from 9×105
cfu/ml to 79×107
cfu/ml. After the study of colonial
characteristics and microscopic examination, 27 isolates of Azotobacter were
found. Further biochemical tests confirmed 20 isolates of Azotobacter sp. And
among them 10 species were A. chroococcum, 6 species were A. vinelandii
and 4 species were A. beijerinckii. The canonical analysis suggested that the
physico-chemical variables such as soil texture (sand, silt and clay), organic
carbon, pH, bulk density, potassium, nitrogen and electric conductivity are
highly associated with organism (TPC) but negatively related to soil microbial
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biomass carbon. In the contrary, variables of gravel, soil microbial biomass
nitrogen and moisture content are not associated with organisms.
Description:
A
Dissertation Submitted to the Department of Microbiology,
Central Campus of Technology,
Tribhuvan University, Dharan, Nepal
In the Partial Fulfillment of the Requirements for the Award of
Degree
Of Masters of Science in Agriculture Microbiology
