TY  - BOOK
AU  - Divya S Nair
AU  - Gowri Priya (Guide)
TI  - Soil biodiversity under organic and integrated nutrient management system and impact on soil quality
U1  - 631.4 
PY  - 2023///
CY  - Vellayani
PB  - Department of Soil Science and  Agricultural Chemistry, College of Agriculture
KW  - Soil Science
KW  - Agricultural Chemistry
KW  - Soil biodiversity
KW  - Nutrient management
KW  - Soil quality
N1  - MSc
N2  - ABSTRACT
A study entitled “Soil biodiversity under organic and integrated nutrient 
management systems and impact on soil quality” was carried out with an objective 
to characterize soil biodiversity in coconut based cropping systems of southern 
laterites (AEU-8) of Kerala under organic and integrated soil management and to 
correlate soil biodiversity with soil quality and plant nutrient availability. The study 
involved soil sample collection and characterization of soil samples for soil 
biodiversity and soil properties.
Soil samples were collected from coconut-based cropping systems under 
organic soil management in the Model Organic Farm, Department of Soil Science 
and Agricultural Chemistry, College of Agriculture, Vellayani (Site 1) and also 
from coconut-based cropping systems under integrated nutrient management in the 
Instructional Farm, College of Agriculture, Vellayani (Site 2). From each site, 10 
composite soil samples each were collected from 0-15cm, 15-30cm and 30-60 cm 
depth.
Soil samples were characterised for soil macro, meso and micro fauna, 
microflora and beneficial microorganisms. Soil biodiversity was estimated from a 
single, pooled sample of each site. The soil samples were analysed for their physical 
(soil texture, bulk density, particle density, porosity, soil moisture content and water 
stable aggregates), electrochemical properties (pH and EC), chemical (cation 
exchange capacity, anion exchange capacity, Total N, P, K, S, available N, P, K, 
Ca, Mg, S, B, Fe, Mn, Cu, Zn and organic carbon) and biological properties 
(microbial biomass carbon, dehydrogenase activity and amylase activity).
Among the soil macrofauna, annelids, hymenopterans, isopods, dermapterans, 
myriapods and carabids were observed. Annelid population was highest in the 
surface soil of site 1 (40 no.m-2
) and these varied significantly among the 
managements across all depths. Hymenopterans were observed only in surface soil
and were found to be significantly higher in site 1 (6 no. m-2
). Isopods were found 
only in surface soil of site 1 (1.33 no. m-2
) and were not observed in site 2. The 
count of dermapterans were found to be higher in site 1 but there was no significant 
difference observed among the managements. Myriapod population (millipedes and 
centipedes) were observed only in the surface and subsurface soil of site 1. Carabids 
(ground beetle) were observed only in the surface soil of site 1. 
Among mesofauna, both acari and collembola were higher in the surface soil of 
site 1 (3983.33 no. m-2
and 4939.33 no. m-2
respectively). Acari population varied 
significantly among the managements at 0-15 and 15-30 cm soil depth while 
collembolans varied significantly across all depths. Soil microfauna (nematodes)
was higher in the surface soil of site 1 (231830 no. m-2
) and their population varied 
significantly among the managements across all depths.
Soil microflora including bacteria, fungi, and actinomycetes were found to be 
higher in the surface soil under organic management (42.6 x 105
cfu g-1
, 18 x 103
cfu g-1
, 36 x 103
cfu g-1
respectively). Significant difference among both 
managements were found in abundance of all organisms at each depth except for 
fungi at 30-60 cm. Beneficial microorganisms including Azospirillum, Phosphate 
Solubilizing Bacteria (PSB) and K solubilizers were cultured and enumerated from 
both soil managements. The population of Azospirllum was higher in the surface 
soil of site 1 (7 x 103
cfu g-1
) and these varied significantly among the managements 
at 0-15 cm and 15-30 cm soil depth. The count of PSB and K- solubilizers obtained 
in the culture media was too low to be recorded.
The soil texture was found to be sandy clay loam for soil samples collected 
from both sites. The sand fraction was observed to be decreasing with depth, while 
silt and clay fractions increased with increase in depth. Significantly lower bulk 
density was observed in organic field (1.31 Mg/m3
in surface soil) at all depths and 
it increased with increase in depth. Higher particle density was observed in the 
surface soil of site 1 (2.34 Mg/m3
) and no significant difference among the samples 
was observed at any depth. Higher porosity was observed in surface soil of site 1 
(46 %) and it varied significantly among the managements across all depths. The 
mean soil moisture content was observed to be slightly higher in soil under INM at 
all depths, but no significant difference between the managements were observed.
Water stable aggregates were higher in surface soil of site 1 (69.34 %) and it varied 
significantly among the managements across all depths. 
All the chemical properties except pH was found to decrease with increase in 
depth. The surface soil of site 1 recorded the significantly higher mean values for 
EC (0.21 dS m-1
), CEC (6.97 C mol (p+
) kg-1
), total N (1986.88 kg ha-1
), total P
(969.92 kg ha-1
), total K (1512 kg ha-1
), total S (947.52 kg ha-1
), available P (88.03
kg ha-1
), available K (361.20 kg ha-1
), available Zn (2.83 mg kg-1
) and OC (0.96 %).
All these properties showed significantly higher mean values in site 1 across all 
depths. The surface soil of site 2 recorded significantly higher mean values for pH
(5.57), available N (222.5 kg ha-1
), B (0.436 mg kg-1
), Fe (16.79 mg kg-1
) and Cu 
(0.99 mg kg-1
). These properties varied significantly among the managements 
across all depths, except available B at 15-30 cm and 30-60 cm, and available Cu 
at 30-60 cm. While AEC, available Ca, Mg, S and Mn did not show significant 
difference among the management at any depth.
The surface soil of site 1 recorded higher microbial biomass carbon (22.96 μg 
g
-1
), dehydrogenase (31.02 μg TPF hydrolysed g-1
soil 24 hr-1
) and amylase (1.24
mU g-1
of soil) activity. All these biological properties decreased with increase in 
depth and were observed to be significantly higher in soil under organic 
management at all depths. 
Organisms observed a positive correlation with most of the physical, chemical 
and biological properties of soil. Negative correlation was observed between soil 
organisms and bulk density and also between hymenoptera and dermaptera with 
soil pH.
From the Bray Curtis dissimilarity index, it is observed that the average 
dissimilarity of biodiversity was 0.262 between the surface soil of organic 
management and INM. This suggests that there are differences in species 
composition, although there are also shared species or similarities to some extent.
Average dissimilarity among the managements decreased with depth. The 
PERMANOVA analysis showed that "depth" had a substantial and statistically 
significant effect, while the "management" factor did not significantly contribute to 
community dissimilarity. The interaction term "management × depth" also proved 
to be non-significant in explaining community dissimilarity. From the Bray Curtis 
dissimilarity index SIMPER analysis was performed and it showed that nematode 
is the species that contributes the largest amount of the difference between 0-15 cm 
and 15-30 cm soil depths and also between 15-30 cm and 30-60 cm soil depths.
From this study, it was concluded that soil biodiversity was positively 
correlated to most of the soil properties and no significant effect was observed in 
the community dissimilarity for management but, depth had a substantial and 
statistically significant effect on community dissimilarity
UR  - https://krishikosh.egranth.ac.in/handle/1/5810221187
ER  -