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Abstracts & Full Texts: Vol. 12, April 2008
Geochemical Distribution of Elements at
Lipad and
Tabin Mud Volcanoes, Sabah
TING TEO MING, AXEL D.
POULSEN & MARCUS JANOPY (Full Text-pdf-1.98MB)
A study was conducted to
determine the chemical characteristics of mud volcanoes at Lipad and
Tabin
situated at Tabin Wildlife Reserve. Both
areas comprise of inner zone (with absence of vegetative cover) and
outer zone
(with vegetative cover). The
concentrations of Fe and Mn at the inner zone for both volcanoes ranged
from
17390-24800 mg/g and
497-941 mg/g
respectively. The total concentrations
of Mg, Na, Ca and K were highest at the inner zones ranging from
3653-6088 mg/g,
1543-19472 mg/g,
291-2875 mg/g and
722-2428 mg/g,
respectively. The concentrations of
these elements at 200 m away from the periphery of the inner zone
decreased to
588-1448 mg/g, 41-139
mg/g,
0.9-30 mg/g and
256-632 mg/g,
respectively. The element distribution
decrease in the outer zone could be associated with the degree of mud
volcanoes
activity. The concentrations of trace
elements such as Zn, Cu, Cr, Pb, Co, Ni and Cd were of the same order
of
magnitude (<100 mg/g) with
no apparent trend between inner and outer zones. This
indicates that the degree of mud volcanoes activity does not
influence the distribution of trace elements.
Hydrophobicity of Soils
Formed over Different Lithologies
EMMANUEL
UZOMA ONWEREMADU (Full Text-pdf-0.72MB)
Using a free survey technique and
special analytical methods, wettability of soils derived from different
parent
materials in central Southeastern
Nigeria were investigated in 2005. Resulting soil
data were subjected to Analysis of Variance (ANOVA) using PROC
Mix-model of SAS, and some soil properties were regressed to
identify leading predictors of soil hydrophobicity in the
study area. Soil hydrophobicity varied among the soil groups
and horizons (p<0.05) in response to differences in soil
properties. Soil moisture, organic matter, clay, sand, sodium
saturation were good predictors of soil hydrophobicity in
soils of the study site although at varying levels of
prediction and parameter combinations. Accuracy of predictions
was very high. Further studies involving detailed sampling,
increasing parameter combinations and geostatistical analysis
should improve the quality of models used to study soil
hydrophobicity in the study area.
Effects
of Anthropogenic Disturbance on Soil Microbial Biomass C, N and P in a
Tropical
Rainforest Ecosystem of Assam,
Northeast India
A. R.
BARBHUIYA, A. ARUNACHALAM , H.N. PANDEY, K. ARUNACHALAM & M.L.
KHAN (Full Text-pdf-0.88MB)
The
effect
of anthropogenic disturbance on soil microbial biomass C, N and P
dynamics in a
tropical rainforest ecosystem of Northeast
India
was studied in undisturbed, moderately disturbed and highly disturbed
stands. Tree species richness in the
community was drastically reduced due to disturbance, from 82 species
in the
undisturbed stand to 13 species in the highly disturbed stand. Soil
organic C,
total Kjeldahl nitrogen and P concentration was low in the disturbed
stands
compared to the undisturbed stand. With the increase in disturbance,
the
microbial-biomass C, N and P decreased significantly (P>0.001)
because of
lower inputs of organic matter to the soil. Microbial biomass C, N and
P ranged
between 226-1060 µg g-1, 27-92 µg g-1
and 15-52 µg g-1,
respectively, in the undisturbed and highly disturbed stands. The
seasonal
pattern of microbial biomass C, N and P was influenced by the variation
of soil
moisture and temperature, with maximum during winter and minimum during
the rainy season. There were significant
positive relationships among microbial biomass C, N and P and SOC, TKN
and P
concentration. Destruction of above ground
vegetation by selective logging and clear felling caused a
significant reduction in microbial biomass in the disturbed
stands.
Organic
Matter, N and P Dynamics of Fine and Coarse Roots in Humid Subtropical
Forest
Ecosystem Exposed to Disturbance in Meghalaya, Northeast India
K. UPADHAYA, H.N.
PANDEY, S.K. BARIK & R.S. TRIPATHI (Full Text-pdf-1.06MB)
Standing fine
(<2mm diameter) and
coarse (>2mm diameter) root mass production, N And
P accumulation, and
turnover rate were studied in two pairs of protected and disturbed
stands of a
subtropical humid forest to examine the response of below-ground parts
to mild
disturbance caused by above-ground vegetation by humans.
Disturbance of mild intensity caused significant reduction
in
biomass accumulation and production of fine and coarse roots. The fine
root
(540-754 gm-2) and coarse root (307-387 gm-2)
mass was
higher in the protected stands, declining (fine root: 422-466 gm-2,
coarse root: 247-305 gm-2) significantly in the disturbed
stands.
The total annual root production was also higher in the protected
stands (1102
-1242 gm-2) than in the disturbed stands (890-940 gm-2).
Live roots (biomass) showed a higher N and P
concentration than the necromass (dead root mass). Nutrient
concentration was higher in the fine
roots compared to the coarse roots. N
and P accumulation in the roots was high (N = 99 - 132 kg ha-1,
P =5
- 8 kg ha-1) in the protected stands and low (N = 76 - 85 kg
ha-1,
P= 4 -7 kg ha-1) in the disturbed stand. The
total input of N to the soil by roots
ranged from 121-132 kg ha-1 in the protected stands to
96-100 kg/ha
in the disturbed stands, whereas P input
was 5 to 7 kg ha-1 in all the stands. The study reveals that
roots
play a significant role in maintaining the organic matter, Nitrogen and
P
status of the soil and is influenced by soil conditions and vegetation
characteristics. Soil and vegetation are
affected due to disturbance, which in turn affects mass,
production, N and P concentration and their accumulation in
the roots. These results are discussed in the present paper
and the information should help further understanding of the
fragility of subtropical humid forest ecosystems.
Carbon and Nitrogen
Stocks of the
Central Clay Plane: Irrigated versus Rain-fed Vertisols
A.R. MUBARAK,
O.M.E. ELSHAMI & F.A. HAMID (Full Text-pdf-1.12MB)
Mitigation of
atmospheric CO2 concentration and
ensuring national food security could be achieved by increasing carbon
sequestration in the soil. We estimated soil organic C and N
sequestered in the
long- (79 years), medium- (46 years) and short-term (22 years) crop
rotation
systems of cotton (Gossypium hirsutum), sorghum (Sorghum
bicolor),
groundnut (Arachis hypogaea), wheat (Triticum aestivum)
and
fallow in Vertisols, both irrigated and rain-fed, of the semi-arid
tropics of Sudan.
Total C pool, comprising soil organic and
inorganic C for the entire profile (0 - 0.90 m) of irrigated Vertisols
was
estimated to be 142, 174 and 99 t ha-1 C for the short-,
medium- and
long- term cultivation, respectively. Under irrigated soils, organic C
made up
31 to 71% of the total C stored in the profile compared to 63 to 73%
under
rain-fed Vertisols. It was estimated that about 25% was lost from total
profile
(0 - 0.9 m) C as CO2 after about 79 years of cultivation
(0.414 t C
ha-1yr-1) of the Gezira cotton scheme. Similarly,
loss
from organic C was estimated at 29% with a rate of 0.208 t C ha/yr.
Total
profile (0 - 0.9 m) N under short- and medium-term cultivation (6.74
– 7.79
t ha-1) was significantly
higher than that under long-term cultivation (5.05 t N ha-1).
However, cropping system had no significant effect on total N (an
average of
8.0 t ha-1) under rain-fed Vertisols. About 65 to 68% of
total
profile N was found below the plough layer (0 – 0.3 m). Since
Vertisols are
heavy clay soils, reducing tillage operations, an alternative
management
practice (for example, using cover crops during fallow periods and
retaining
crop residues in situ) would help in
reducing C loss in one of the largest cotton schemes in Africa.
Enhancing
Rice Establishment in Anaerobic Direct Seeding Through Control of Weedy
Rice
V.JEYANNY, S.R. SYED
OMAR, M. AZMI, & A.S. JURAIMI (Full Text-pdf-0.98MB)
A glasshouse and
field trial was conducted to investigate
the effects of pre-treated rice seeds on cultivated rice and weedy rice
establishment in direct seeding planting system. Treatments applied
were wet
seeding (T1) and water (anaerobic) seeding at 10 cm flooding depth
(T2). In the
glasshouse trial, water seeding significantly reduced weedy rice
seedling
emergence almost three-fold compared to control; the usage of
pre-treated seeds
in both seeding methods significantly increased the viability of
cultivated
rice compared to weedy rice. The weedy rice population was
significantly
decreased (32%) in the water seeding plot compared to wet seeding at 90
DAS in
season 2/04 in the field. The water seeding technique also profoundly
reduced
weedy rice population by about 50% at both 60 and 90 days after sowing
(DAS)
the following season (season 1/05) compared to wet seeding.
The use of
pre-treated seeds for the anaerobic direct seeding technique
had an advantage on seedling vigour that out- competed the
growth of weeds, and increased rice seeds
viability.
Amelioration
of
Cheringa
Acid
Sulfate Soil and Screening
of Acidity-Salinity Tolerant
Rice
Varieties in a Simulation Study
MD. H.R. KHAN, S.M. KABIR, M.M.A. BHUIYAN, H.P. BLUME, Y.
OKI & T.
ADACHI (Full Text-pdf-1.80MB)
A
simulation study was conducted to evaluate
the effects
of
basic slag (BS10: basic
slag 10 t ha-1
and
BS20:
basic slag 20 t ha-1),
aggregate
size (A20: aggregate sizes of soil less than 20 mm and A30:
aggregate sizes of soil, 20-30 mm) and
groundwater depth (Gw0:
no influence of groundwater and Gw50: groundwater beneath 50
cm of
the soil surface) in pre-leached Cheringa acid sulfate soil (Typic
Sulfic
Halaquept) in relation to the production and screening
of the acidity-salinity tolerance of
18 rice cultivars. The results obtained from the study showed that
the physico-chemical properties of the pre-leached acid sulfate soil
were
strongly (p=0.05) influenced by the application of basic slag,
aggregate size
and maintenance of groundwater depth. Among the individual treatments,
the
application of BS20 ranked first with regard to the
reclamation of
soil and production of rice, followed by Gw50 > A30.
The average soil data of all the treatments at post harvesting of rice
cultivars were increased by 1.6 units for soil pH(water: 1:2.5)
and
34 to 1803% for the contents of N, P, Ca
and Mg, while the saturations of Fe, Al and Na were decreased by 24 to
88%
compared with the initial soil. The
maximum quantity
(6.9 t/ha) of rice grain was attained by the local (Cox’ Bazar)
Kajashail, followed by the Bangladesh
rice (BR) line 5828-11-1-4 (6.7 t ha-1) > BR 23 (6.6 t ha-1).
Among the rice varieties, the BR lines were
found to be the most effective for rice production in the soil,
followed by the
local varieties > BR varieties > international rice (IR)
varieties.
Almost similar and significant (p=0.05) effects were observed for plant
height,
tiller production, straw yield and yield components of the rice
cultivated in the soil.
Characterization of Malaysian Sewage
Sludge and Nitrogen
Mineralization in Three Soils Treated
with Sewage Sludge
A.B. ROSENANI,
D.R. KALA AND C.I. FAUZIAH (Full Text-pdf-0.99MB)
Studies
to determine the chemical composition of sewage sludges
produced in Malaysia
and potentially mineralisable nitrogen (No)
and mineralization rate
constant (k) of sewage sludge in three Malaysian soils are
reported. The sludges collected from ten wastewater
treatment plants in Malaysia
were acidic in nature and the N, P, K, Ca and Mg contents were
variable. The
heavy metal (Pb, Cd, Cu, Mn and Ni) concentrations of the sludges,
except for
Zn, were below the European Union Maximum permitted level in sludges.
In an
incubation study, three topsoils of Bungor, Jawa and Serdang series
were
treated with three rates (0, 140 and 420 kg N ha-1) of
dewatered
sewage sludge and incubated about 60% of the water holding capacity for
12
weeks. Mineralization of N exhibited a slow initial rate, followed by a
rapid
increase in rate in week 4 to 8. Accumulation of mineral N ranged from
50.5 to
147.6 mg kg-1 soil. Bungor
and Jawa series had higher N mineralization than Serdang series. Sludge
added
at 420 kg N ha-1 resulted in the highest concentration of
net
mineralised N. Values of potentially mineralisable N, (No),
and mineralization rate constant, (k), ranged
from 23.4 to 137.5
mg N kg-1 soil and 0.036 to 0.082 week-l, respectively. It was concluded
that N mineralization of the sewage sludge treated soils was
dependent on the application rate of sludge and soil
type.
Concentrations
and Chemical Forms of Heavy Metals in Some Ultisols
in Johore, Peninsular Malaysia
S. ZAUYAH, B.
JULIANA, & C.I.
FAUZIAH (Full Text-pdf-0.76MB)
The
concentrations of heavy metals in soil are associated with
biological and geochemical cycles and are influenced by anthropogenic
activities such as agricultural practices, industrial activities and
waste
disposal. A total of 36 surface soil samples (Typic Kandiudult, Rengam
Series)
were collected from some major vegetable growing areas developed over
granite.
Twelve soils from areas not cultivated with vegetables but also
developed over
granite were also sampled for background values. The pseudo-total heavy
metals,
(Cu, Pb, Zn and Ni) were determined by the aqua-regia method. Chemical
properties such as pH, organic carbon and CEC were also analysed. Some
selected
cultivated soil samples (24 of Ultisols and 12 of background soils)
were
analysed for chemical partitioning using a modified Tessier’s
procedure (F1:
exchangeable fraction, F2: fraction bound to organic matter, F3:
fraction bound
to amorphous iron oxides and F4: residual fraction). Mean values of the
total
heavy metals for the cultivated soils are Cu (23.3 mg kg-1),
Pb
(18.0 mg kg-1), Zn (49.4 mg kg-1) and Ni (6.0 mg
kg-1).
Comparison of these values to the contents in the background soils show
that Cu
and Zn have significantly increased. However, all these values are
below the
contaminated levels established for the country’s agricultural
soil limits (95th
percentile). From the partitioning study, the general trend in the
Ultisols for
Pb and Ni is residual > oxalate >exchangeable>organic. For Zn
and Cu,
the oxalate extractable phase is highest followed by the residual
phase. Zinc
and Pb contents in the soils are also positively correlated with the pH
of the
soil.
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