Malaysian Journal of Soil Science (MJSS)
Abstracts
and Full Texts: Vol. 10
Isolation of
IAA-Producing Rhizobacteria for Enhanced Growth of Sweetpotato
O. RADZIAH, M. LUSI
& A. R. ANUAR
(Full
Text-pdf-5.84MB)
The
ability to produce the indole-3-acetic acid (IAA) by plant
growth-promoting rhizobacteria
(PGPR) is one of the mechanisms for
promoting plant growth. The survival of
sweetpotato under low input farming
could be associated with the production of such
hormones. Studies were conducted to isolate IAA-producing
rhizobacteria from rhizosphere of different varieties of
sweetpotato grown on different soils.
Media containing root exudate of sweetpotato var.
Gendut was used to screen for rhizobacteria
associated with sweetpotato. Growth performance
of the IAA-producing rhizobacterial
isolates was then evaluated using sweetpotato
var. Gendut cuttings under glasshouse conditions. A total of 115 rhizobacterial
strains were isolated from the different sweetpotato varieties. Only
48 of the local isolates were able
to grow in the root exudate medium
with 18 of them producing 1AA ranging
from 4.01 to 8.56 mg mL-1).
Inoculation
of the IAA-producing isolates on Gendut showed
significant differences in the root dry weight, shoot: root
ratio and phosphorus uptake by the plants.
Saturated Hydraulic
Conductivity of Some Saprolites from PeninsularMalaysia
J. HAMDAN, CHNG LOI
PENG & B. RUHANA
(Full Text-pdf-6.57MB)
A study was conducted to evaluate the hydraulic
conductivity of saprolites and their potential use as a wastewater
treatment in Malaysia. Samples
of granitic, basaltic, schist and shale saprolites were taken
from 16 locations throughout Peninsular Malaysia. These
samples were morphologically described and air-dried for
physical analyses. The infiltration rate study of the
saprolites was conducted both in-situ and in the laboratory. The study showed that
granitic saprolite had the highest Ksat value while basaltic had the
lowest value in both laboratory and in-situ methods.
Several factors influenced the Ksat value, namely clay and
sand content, porosity, pore shape and pore sizes. Both pore size and
shape analysis influenced the Ksat value especially
mesopores, Me (30 £ 75 mm), macropores, Mc (> 75 mm), vugh and channel shapes. A model to predict the Ksat
of saprolites was proposed as follows: Ksat = 16.859 —
0.182 qfc— 0.183 qwp — 0.128 Si + 0.112 Moist where, qfc and qwp is the moisture content
retained at 9.8 kPa and 1500 kPa, respectively, Si is the
silt content, and Moist is the air-dried moisture
content. The study suggests that shale and basalt saprolites
are suitable for in-situ wastewater treatment because of their
slow to very slow infiltration rate. This will provide ample
time for bacteria and viruses to be removed from the effluent
by filtration and adsorption onto particle surfaces and for
organics to stabilise the
wastewater. + 0.112 Moist
Modelling of Escherichia coli Density
on Land and Concentration in Surface Runoff
T. Y. LING, R. L. BENGTSON, C.
M. DRAPCHO, E. C.
ACHBERGER, G. J. SABBAGH & J. JACKSON
(Full Text-pdf-5.10MB)
Integrated farming of crop and animal enables resources
from animal waste to be utilised. However, bacterial pollution
is a concern. In this study, a bacterial model, ECOLI,
was developed to simulate Escherichia coli density daily
on land and its concentration in surface runoff. Loss of
E. coli was assumed to occur through decay, runoff, sediment and
percolation. E. coli decay was assumed to follow the first order decay
affected by soil pH, soil temperature and soil moisture. In testing the
model, the ECOLI model was interfaced with the GLEAMS-SWT hydrologic and
erosion model. Calibration and evaluation was performed with field-scale
data from Franklinton, Louisiana . Fresh cow manure
was applied on grassed plots and runoff was collected and
analysed. Predicted E. coli concentrations versus observed E.
coli concentrations in surface runoff gave a regression line
with coefficient of determination of 0.993, intercept of 0.011
and a slope of 0.995 indicating good agreement of model
predicted concentrations with observed concentrations. The
ECOLI model can be used to study the effects of various animal
waste application practices such as waste loading rate, timing
of application and frequency of application. More research
needs to be conducted to incorporate databases so as to expand
the capabilities of this model.
Domestic
Sewage Sludge Application on an Acid Tropical Soil: Part II.Heavy
Metals Uptake by Maize and Accumulation in the Soil
ROSAZLIN
A., I. CHE FAUZIAH, A.B. ROSENANI
& S. ZAUYAH
(Full
Text-pdf-9.89MB)
Recycling
of sewage sludge to agricultural land can be beneficial from the aspect
of essential plant nutrients and organic matter supplement to the soil
and plant system. However, sewage sludge also contains varying amounts
of heavy metals which may pose a metal toxicity hazard to crops and
consumers of these crops. Thus, the uptake of heavy metals by crops and
the fate of these heavy metals in soils need to be monitored. In
general, domestic sewage sludge has lower concentrations of heavy
metals compared to the mixed light industry and domestic sludge type.
Therefore, domestic mixed with light industry type sludge is hazardous
and unsuitable for agricultural use. The concentration of heavy metals
in domestic sewage sludge does not exceed the maximum permitted
concentrations (MPC) of the European Community Standard (ECS) for land
application. Sewage sludge application appears to have little effect on
increasing heavy metal concentrations in the soil and grain after the
third maize cycle. The concentration of heavy metals in the soil was
below the MPC of the ECS and ranged from 12.44-35.44 mg kg-1 Zn,
5.00-9.80 mg kg-1 Cu, 0.60-2.44 mg kg-1 Cd ,
7.16-24.04 mg kg-1 Pb and 7.44-11.36 mg kg-1 Ni.
The concentration of heavy metals in maize grain which ranged from
4.95-19.18 mg kg-1 Zn, 0.56-2.60 mg kg-1 Cu,
0.037-0.052 mg kg-1 Cd, 0.034-0.052 mg kg-1 Pb
and 0.66-1.22 mg kg-1 Ni was below the MPC values of the
Malaysian Food Act 1983 and Food Regulation 1985 (fresh weight basis
and 60% moisture content). Correlations were found between (i) total Pb
concentration in the soil (r=0.53**) and Pb content in maize grain;
(ii) available heavy metals or 1 M NH4NO3
extractable Cu (r=-0.25*), Pb (r=O.40**) and Ni (r=0.51**) in the soil
and metal content in the grain(significant); (iii) total concentrations
of Cd r=-0.43**, Pb r=0.43**, Zn r=0.30* and Ni
r=-0.40** in soil and the metal content in leaves and stem: (iv)
available heavy metal concentration of 1 M NH4NO3
extractable Zn (r=0.41**) and Ni (r=0.55**) in soil and leaves and stem
content (significant); and (v) concentration of Cd
(r=-0.40**) and Ni (r=-0.52**) in soil and content of these metals in
sheaths band cobs and between available or 1 M NH4NO3
extractable Cd (r=0.28*), Pb (r=0.39**) and Ni (r=0.86**) in soil and
content of the metals in sheaths and cobs. From this study, it can
be concluded that soil extracted with NH4NO3 is
suitable for determining available heavy metals in sludge-amended soils.
Effect
of Coffee Bean Residue and Time on Soil Nitrogen Availability
TENAW WORKAYEHU, M.H.A. HUSNI,
A.R. ANUAR & ZAHARAH A.R
(Full
Text-pdf-7.21MB)
Burning
and dumping of coffee bean residue has brought on environmental
problems. On the other hand, low soil fertility has resulted in
declining crop production. For efficient use, mineralisation of N from
coffee residue applied as surface mulch was evaluated using four rates
of residue (0, 3, 6 and 9 Mg ha-1) combined with five
periods of incubation (0, 30, 60, 90 and 120 days) in a pot experiment
with three replicates. The low quality coffee residue resulted in
immobilisation of soil N (varied between -7.1 to -2.8 g kg-1),
which (R2 = 0.72**) which persisted linearly up to the end
of the experiment. The regression equation indicates that
mineralisation of N is controlled by lignin, L/N and cellulose (R2
= O.99**), while residue N at each period of incubation is controlled
by L/N (R2 =
0.56**). Increased application rates of coffee residue reduced
immobilisation of N (a quadratic response). N mineralisation
rate (Nk) was significantly higher (1.5 mg kg-1
d-1) in the first 30 days of incubation, whereas 3 Mg ha-1
residue had a significantly high Nk value (1.3 mg kg-1 d-1) compared to
higher rates. The regression equation to predict N
mineralisation rate (Nk) indicates that time of incubation and
concentration of N in the residue control N mineralisation
rate (R2 = O.80**).
The
Kinetics of Biodeconcentration for Nitrate: Case Study on Microbial
Denitrification and
Plant Absorption
SARWOKO
MANGKOEDIHARJO
This research was conducted to
study the kinetics processes of microbial denitrification and the
kinetics processes of plant absorption. The test plants were spinach,
peanut and grass. The test solution contained nitrate of 24 mg N/L,
glucose of 64 mg C6H12O6/L and phosphate of 0.5 mg P/L.
The results showed that the kinetics
of nitrate biodeconcentration processes were exponential: Ct
= Co*e-kt. The rate constant for microbial
denitrification was stated as kd which was equal to 0.0786 day-1.
The rate constant of plant absorption was stated as ks, and the rates
for spinach, peanut and elephant grass were 0.0745, 0.0921 and 0.1226
day-1, respectively.
The time to process 50 % of nitrate biodeconcentration
efficiency (t½), as the half time of nitrate
biodeconcentration, for microbial denitrification it was 8.8
days and for nitrate absorption by spinach, peanut, and
elephant grass, the times were 9.2, 7.5, and 5.6 days, respectively. Therefore,
elephant grass they was more effective in suppressing nitrate than
peanut, denitrifier and spinach.
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