bluuebunny/crossref_metadata_2025 huggingface dataset:
Sedoheptulose-1,7-bisphosphate phosphatase activity of chloroplast fructose-1,6-bisphosphatase: identification of enzymes hydrolysing fructose-1,6-bisphosphate and sedoheptulose-1,7-bisphosphate in stromal extracts from chloroplasts of spinach (Spinaci
Authors: Ashton Anthony R.
Published: August 2004

The identity of enzymes present in soluble extracts of spinach(Spinacia oleracea) chloroplasts that are capable ofhydrolysing fructose-1,6-bisphosphate and sedoheptulose-1,7-bisphosphate hasbeen investigated using antibodies against purified spinach chloroplastfructose-1,6-bisphosphatase (EC 3.1.3.11). The activity of purifiedfructose-1,6-bisphosphatase, which can exist in a less active oxidised form ora more active reduced form as well as total fructose-1,6-bisphosphatase instromal extracts is inhibited completely by the antiserum. Apparently, only asingle enzyme, which can exist in an oxidised or reduced form, is responsiblefor hydrolysis of fructose-1,6-bisphosphate in the chloroplast. Purifiedchloroplast fructose-1,6-bisphosphatase can also exhibitsedoheptulose-1,7-bisphosphatase activity, but only when reduced. Oxidisedchloroplast stromal extracts contain little or nosedoheptulose-1,7-bisphosphatase activity whereas reduced extracts containsedoheptulose-1,7-bisphosphatase activity. Antiserum against fructose-1,6-bisphosphatase does not inhibit sedoheptulose-1,7-bisphosphatase activitydetectable at pH 8 or less with 2 mM Mg2+ butsubstantially inhibits (up to 60%) the sedoheptulose-1,7-bisphosphataseactivity at higher pH or Mg2+ concentration, i.e.conditions under which the chloroplast fructose-1,6-bisphosphatase exhibitssedoheptulose-1,7-bisphosphatase activity. Apparently, the chloroplast stromacontains at least two enzyme species capable of hydrolysingsedoheptulose-1,7-bisphosphate, a specific sedoheptulose-1,7-bispho-sphatase(EC 3.1.3.37) and the chloroplast fructose-1,6-bisphosphatase.
The influence of extracellular-side Ca2+ on the activity of the plasma membrane H+-ATPase from wheat roots
Authors: Qiu Quan-Sheng , Su Xue-Feng
Published: August 2004

Plasma membrane vesicles were purified from wheat roots by discontinuous
sucrose gradient centrifugation and two-phase partitioning methods. The
influence of extracellular-side Ca2+ on the activity of
the plasma membrane H+ -ATPase from wheat roots was
studied. The results showed that the ATP hydrolytic activities of the plasma
membrane H+ -ATPase were inhibited by the
cytoplasmic-side Ca2+. Within 0~200 µmol/L the
ATPase activity decreased gradually with the increase in
Ca2+ concentration; the ATPase activity was inhibited by
40% when Ca2+ concentration was 1000
µmol/L. However, the ATP hydrolytic activities were recovered by the
presence of extracellular-side Ca2+. Results showed that
the ATPase activities were increased with the increase in extracellular-side
Ca2+; when the extracellular-side
Ca2+ was 1000 µmol/L, the ATPase activity was
recovered by 87.5%. Further studies found that the extracellular-side
Ca2+ increased the DPH polarisation and decreased the
MC540 fluorescence intensity, showing that membrane fluidity was decreased and
membrane stacking was increased by the external Ca2+.
The above results suggested that the plasma membrane H+
-ATPase could be regulated by the extracellular side
Ca2+ through affecting the plasma membrane physical
states.
Developmental changes of catalase and superoxide dismutase isoenzymes in zygotic and somatic embryos of horse chestnut
Authors: Bagnoli F. , Capuana M. , Racchi M. L.
Published: August 2004

Catalase (CAT) and superoxide dismutase (SOD), two of the major antioxidant
enzyme systems, were examined by native PAGE at different stages of zygotic
and somatic embryogenesis of horse chestnut
(Aesculus hippocastanum L.). During both zygotic and
somatic embryogenesis, CAT and SOD specific activities increased, but
electrophoretic analysis revealed remarkable differences in the isoenzyme
patterns. Two CAT isoforms were differentially present during zygotic
embryogenesis. The transition from the fast to the slow migrating form
occurred in July, approximately 2 months after pollination. In contrast to
zygotic, the two isoforms were continuously detectable during somatic
embryo-genesis. In fact, with the exception of the callus stage, in which only
one form was present, both of the CAT isoforms are equally active during the
somatic embryo development.
Unlike CAT, all SOD isoenzymes, one Mn-SOD and five Cu/Zn-SODs, were
present during all the stages of zygotic embryo formation, but only Mn-SOD and
an Fe-SOD were detected during somatic embryogenesis. These results suggest
the occurrence of oxidative stress conditions during
in vitro culture which, in horse chestnut, could account
for the difficulties observed in the development of the somatic embryo into a
plantlet.
Effect of quinclorac on auxin-induced growth, transmembrane proton gradient and ethylene biosynthesis in Echinochloa spp.
Authors: Lopez-Martinez Nuria , Shimabukuro Richard H. , Prado Rafael De
Published: August 2004

The mechanism of action of quinclorac and its selectivity between rice and
resistant (R), intermediately tolerant (I) and susceptible (S)
Echinochloa spp. were investigated. The effect on the
cell membrane potential (Em),
stimulation of cell elongation growth, ACC production and ethylene formation
were examined to verify the auxin characteristics of quinclorac and the
possible mechanism of selectivity. Quinclorac did not induce cell elongation
growth, neither did it cause hyperpolarization of
Em due to the stimulation of
H+ -ATPase activity. Quinclorac increased ethylene
biosynthesis by increasing the ACC content in susceptible plants, possibly by
affecting the autonomous auxin-regulated ACC synthase gene. Increased ethylene
biosynthesis was correlated with the phytotoxicity of quinclorac. Ethylene
biosynthesis due to quinclorac treatment in I and S biotypes increased 3 and 7
times, respectively, but quinclorac treatment had no effect on ethylene
biosynthesis in R Echinochloa spp. and rice at the
applied dosages. Quinclorac caused an increase of ACC concentration in the S
biotype that was 2.5-fold more than the control. The addition of an ethylene
biosynthesis inhibitor decreased the phytotoxicity of quinclorac. The
mechanism of selectivity between susceptible and tolerant species/biotypes
may be related to the formation of HCN as a coproduct during the stimulation
of the ethylene biosynthesis caused by the herbicide only in susceptible
grasses.
The interplay between limiting processes in C3 photosynthesis studied by rapid-response gas exchange using transgenic tobacco impaired in photosynthesis
Authors: Ruuska Sari , Andrews T. John , Badger Murray R. , Hudson Graham S. , Laisk Agu , Price G. Dean , Caemmerer Susanne von
Published: August 2004

A gas-exchange system with a rapid response time was used to study the
interplay between rate-limiting processes of C3
photosynthesis in wild-type tobacco (Nicotiana tabacum
L. cv. W38) and transgenic tobaccos with antisense DNAs directed against the
Rubisco small subunit (anti-SSu plants) or the chloroplast
glyceraldehyde-3-phosphate dehydrogenase (anti-GAPDH plants). High
ribulosebisphos-phate (RuBP) pools were generated in leaves by exposing them
briefly to very low CO2, after which they were
transferred to varying CO2 concentrations, and transient
CO2 assimilation rates were measured within the first
2–3 s. Comparison of the transient (RuBP-saturated) and steady-state
rates confirmed that the CO2 assimilation rate in
anti-SSu plants was RuBP-saturated (i.e. Rubisco limited) at all intercellular
CO2 partial pressures
(Ci), and that, in anti-GAPDH
plants, the transition from RuBP-saturation to RuBP-limitation occurred at
lower assimilation rates and lower
Ci as GAPDH activity was
decreased. In addition, we investigated whether the integrated
post-illumination CO2 uptake could be used as a
non-destructive means of estimating RuBP pools in leaves. In wild-type plants
there was generally a good agreement between RuBP pools extracted from leaves
after rapid freeze-clamping and estimates made from post-illumination
CO2 uptake. However, in the anti-SSu plants, the post-
illumination CO2 uptake underestimated the actual RuBP
content and the discrepancy became larger as the Rubisco content decreased.
Possible explanations for this are discussed.
Australian Journal of Plant Physiology: Editorial report
Authors: Martinelli Laurie
Published: August 2004

Gene tagging with insertional mutagens greatly facilitates the isolation of
novel genes. A new collection of Arabidopsis T-DNA tag
insertion lines (n=2165) was generated by
in planta transformation. Whole plants were
vacuum-infiltrated in a suspension of Agrobacterium
carrying the pGKB5 tagging vector. The efficiency of transformation increased
with addition of the surfactant Silwet L-77 (0.005% v/v) to the
Agrobacterium suspension. Visual screens of the T-DNA
lines identified two mutants with floral defects. Allelism tests suggested
that a mutation in the GIGANTEA gene was responsible for
the late-flowering phenotype of one of the mutants. Linkage analysis indicated
that the GIGANTEA gene was tagged in this mutant.
Residual management of sulfur applied to soybean or wheat in a soybean - wheat system on Vertisols
Authors: Ganeshamurthy A. N. , Takkar P. N.
Published: August 2004

In a 3-year experiment on a typic Haplustert low in soil test sulfur (S),
residual effects of S applied to either soybean or wheat in a
soybean–wheat system were measured for seed yields, recoveries of added
S, and changes in the soil test S. Sulfur as gypsum was applied at 5 rates
(0–80 kg S/ha) to soybean and 4 rates (0–60 kg S/ha) to
wheat during the first year. In subsequent years the residual effects were
studied in relation to fresh application of 40 kg S/ha to each crop. Seed
yields of soybean and wheat were increased significantly by the application of
S to each crop. The rate 80 kg S/ha applied to soybean showed residual
effects in 2 succeeding crops, while 60 kg S/ha applied to soybean or
wheat showed residual effect in only 1 succeeding crop. The S applied to wheat
was more effciently utilised than that applied to soybean in rotation. The
rates 53 and 70 kg S/ha (calculated via regression equations) applied to
soybean gave 90% of the seed yield of freshly applied S at 40 kg/ha
in the succeeding wheat and soybean crops, respectively, and 57 kg S/ha
applied to the wheat crop gave 90% of the seed yield in the succeeding
soybean crop. The recoveries of added S were greater with smaller rates of
added S and were greater in the first 2 residual crops. Soil test S was
adequate only in the first year and fell below critical level in the
subsequent cropping period. Cumulative S uptake determined the levels of
available S in the soil.
Changes in soil chemistry in efluent-irrigated Pinus radiata and Eucalyptus grandis plantations
Authors: Falkiner R. A. , Smith C. J.
Published: August 2004

Two tree species (Pinus radiata and
Eucalyptus grandis) were planted in 1991 and irrigated
weekly with either secondary-treated effluent or bore-water, in an
effluent-irrigated plantation at Wagga Wagga, NSW. Changes in soil salinity,
sodicity, alkalinity, and the accumulation of potentially toxic elements after
2 and 4 irrigation seasons were studied. The average sodium adsorption ratio
(SAR) and electrical conductivity (EC) of effluent were 4·8 and
0·79 dS/m, while in bore water they were 3·3 and 0·70
dS/m, respectively. Effluent was applied at 3 rates: the water-use rate of
the plantation less rainfall (medium treatment, M), a nominal rate 0·5
times M (low treatment, L), and a nominal rate 1·7 times M (high
treatment, H). The bore-water treatment (W) was irrigated at its water-use
rate less rainfall.
Salinity of saturation paste extracts in the surface 0·05 m increased
from a pre-treatment value of 1 dS/m to 2–3 dS/m after 4 years
of effluent irrigation. The increase in soil salinity was consistent with the
salt loading for the different irrigation treatments. Similarly, exchangeable
sodium percentage (ESP) increased in all treatments. The ESP was generally
<2% at the start of the experiment and increased to a maximum of
25% in the 0·3–0·4 m soil layer of treatment L.
Values had changed throughout the 4 irrigation seasons and the soil profile
does not appear to have reached a steady-state condition.
Soil pH increased in all treatments. The largest increase (≈0·7)
occurred in treatment H, while treatment W had the smallest increase
(≈0·4). The increase in soil pH caused a decrease in exchangeable Al
and Mn in the upper 0·4 m of the soil profile in all treatments.
Effective cation exchange capacity (ECEC), approximated by the sum of the
extractable cations, increased significantly in the upper 0·3 m of the
soil profile after 2 and 4 irrigation seasons, but there was no significant
change in ECEC below 0·3 m.
The economics of soil structural degradation under cropping: some empirical estimates from New Zealand
Authors: Scrimgeour F. G. , Shepherd T. G.
Published: August 2004

Soil structural degradation is a problem of some arable farms in New Zealand.
This paper presents economic estimates of the significance of the loss of soil
structure to farmers and the Manawatu region of New Zealand. Contingent
valuation surveys of farmers and the wider community were used to estimate
both use and non-use values. The results show the significance of compaction
on both farm profits and land values, together with the lack of knowledge of
the wider community concerning this problem. They reinforce the importance of
careful farm practice, further scientific research, and a considered public
policy response.
Phosphate fertiliser residues in wheat-growing soils of the Western Downs, Queensland
Authors: Strong W. M. , Best E. K. , Cooper J. E.
Published: August 2004

Effects of repeated annual application and residual effects of past phosphorus
(P) applications were studied at Billa Billa and The Gums, Queensland, on 2
Vertisols representative of a large cropping area in this region. Phosphorus
was applied annually at 0, 4, 8, 12, and 25 kg/ha at sowing to each wheat
crop between 1978 and 1988. Phosphorus was also applied at 25, 50, 100, 200,
or 400 kg/ha as a once-only application, before wheat was sown in 1978,
and was incorporated by tillage.
Pot experiments were conducted each year with soil (6 kg/pot) gathered
from field plots in May before wheat sowing to determine the residual value
(RV) of previously applied P fertiliser under standard conditions of frequent
watering. In 1979 the RV was determined in a second series of pots with a
water deficit to simulate conditions of plant moisture stress that were to
dominate the field experiments. The RV of P fertiliser was reduced to
one-third that determined under well-watered conditions. Low residual values
(8–47%) determined in the field in 1979 for P rates 25 and 50
kg/ha applied in 1978 were probably due to reduced P uptake from dry
topsoil throughout which P residues were incorporated by tillage. By contrast,
P applied annually at a low rate (4 or 8 kg/ha) in a band close to seeds
created profitable responses when evaluated over the sequence of successive
wheat crops.
The bicarbonate-extractable soil test value (Pbf) on
either soil fertilised annually for n years with P at a rate R
(kg/ha· year) was described by the model
where Pbu is the soil test value (mg/kg) of
unfertilised soil.
Modelling nutrient uptake: a possible indicator of phosphorus deficiency
Authors: Mendham D. S. , Smethurst P. J. , Moody P. W. , Aitken R. L.
Published: August 2004

An understanding of the processes controlling soil nutrient supply and plant
uptake has led to process-based models that can predict nutrient uptake and
the concentration gradient that develops at the root surface. By using this
information, it may be possible to develop an indicator of soil phosphorus
status based on the predicted uptake and/or concentration of phosphorus
(P) at the root surface. To identify the potential for such a test, the
relationships between model output and observed plant growth were examined
using data from a published experiment. The experiment was initially designed
to investigate the relationship between common indices of soil-available P and
the growth of maize (Zea mays) in 26 surface soils from
Queensland. There was a high correlation between observed and predicted P
uptake, and between relative dry matter yield and predicted P uptake. The
predicted concentration of P at the root surface was also highly correlated
with P uptake and dry weight increase. It is hypothesised that the short
growth period (25 days) was responsible for the high correlation between P
uptake and measured soil solution P. The hypothesis that a predicted
concentration of P at the root surface or predicted P uptake may be valuable
indicators of P deficiency in the longer term still remains to be tested.
Effects of animal effluents on the phosphorus sorption characteristics of soils
Authors: Holford I. C. R. , Hird C. , Lawrie R.
Published: August 2004

Two groups of soils were examined to determine the effects of dairy, pig, or
sewage effluent and other materials containing phosphorus (P) on their P
sorption characteristics, using the Langmuir equation to estimate values of
both sorption capacity and sorption strength. There were 19 soils (0-15 cm)
from 6 sites in the Williams River catchment and 3 soils (0-100 cm) from
Bermagui, all from coastal New South Wales.
Effluent usually decreased P sorption capacities of the Williams River soils,
and in 3 soils the capacities were reduced to zero. Sorption strength was
reduced substantially by effluent treatment in all soils except one, which had
received effluent for only 3 years. Sorption strength, but not necessarily
capacity, was also lower after treatment with poultry manure or chicken litter
than after treatment with superphosphate only. Where effluent did not decrease
sorption capacity there was a substantial increase in total carbon and iron,
both of which could increase sorption capacities.
After 3 years of effluent treatment of the Bermagui soil, sorption capacities
had been reduced in the top 70 cm depth, the extent of the reduction varying
from 17% at 0-7 · 5 cm depth to 38% at 40-70 cm depth.
Sorption strength was reduced in the top 40 cm depth only. After 12 years of
effluent treatment, sorption capacities and strength had also decreased at the
deeper sampling depths (to 100 cm), and the average reduction in capacity was
about 40%. These results suggest that P leaching will begin well before
the total sorption capacity has been saturated. There was a direct and
significant correlation between the sorption strength of the untreated soil
and the percentage saturation reached before leaching began. Further
saturation of the sorption complex appears to be slow after this degree of
saturation has been reached, and it seems that P leaching exceeds adsorption
during this phase. There was also a negative correlation between sorption
strength and KCl-soluble P in all soils, suggesting that soil P solubility and
potential saturation are both controlled by this characteristic.
Changes in some properties of topsoil at Tarong Coal - Meandu Mine coalmine with time since rehabilitation
Authors: Loch R. J. , Orange D. N.
Published: August 2004

Three sites were studied at the Meandu Mine, Tarong, where vegetation had been
established for 2, 4, and 6 growing seasons. Topsoil (a grey sandy loam,
developed on sandstone) had been spread over sandstone spoil at all sites, to
a depth of approximately 200 mm.
At each site, areas were studied where either (i) all
vegetation had been removed and the soil was disturbed to destroy any
macropores that had developed, then allowed to consolidate under rainfall, or
(ii) vegetation was clipped and pores in the soil were
left undisturbed and intact. This allowed separate assessment of soil pores
associated with re-aggregation and of the frequency and importance of stable
macropores formed by soil fauna and by plant roots. Disc permeameters were
used to measure hydraulic conductivities at the soil surface, and organic
carbon and aggregate size distributions at the soil surface following rainfall
wetting were measured.
For bare, consolidated soil, hydraulic conductivities indicated that
development of pores in the topsoil had reached a maximum after 4 seasons.
This was consistent with aggregate size distributions after rainfall wetting,
which indicated little change between 4 and 6 seasons. Hydraulic
conductivities of vegetated areas showed responses to both length of time
under vegetation and to plant species.
The results showed that measurements of soil structure and of infiltration
parameters made when soil was spread and rehabilitation commenced will greatly
underestimate the long-term hydraulic conductivity of minesoils. Where
long-term runoff, water balance, and vegetation growth are being considered,
it would be preferable to measure input parameters on areas of established
vegetation (preferably after at least 4 seasons of plant growth).
An investigation of the relationships between dispersion, power, and mechanical energy using the end-over-end shaking and ultrasonic methods of aggregate stability assessment
Authors: Raine S. R. , So H. B.
Published: August 2004

The dispersion and energies applied by the end-over-end shaking and ultrasonic
methods of assessing aggregate stability were compared. The simple calculation
of the kinetic energy of the falling water within the shaking cylinder
(0·72 W) was found to underestimate the total energy associated with
dispersion, which was estimated as the equivalent energy during the initial
period of shaking, as 1·92±0·18 W. A range of mechanical
energies up to 24·95 W was applied to suspensions of 2 Vertisols with
contrasting stability using the ultrasonic and the end-over-end shaking
techniques. Both power and total energy applied was found to affect
significantly (P < 0·05) the dispersion of
material sized <20 and <2 µm. The results confirmed the presence
of aggregate hierarchy, with the end-over-end shaking treatment being unable
to disperse completely the <2 µm material for either soil. An
increase in the power applied by the ultrasonic probe increased the rate of
aggregate breakdown for the stable soil but produced no effect on rate of
breakdown in the unstable soil.
Soil acidification under some tropical agricultural systems. 1. Rates of acidification and contributing factors
Authors: Moody P. W. , Aitken R. L.
Published: August 2004

A paired site (developed v. undeveloped) approach was used to calculate
acidification rates in several agricultural systems of tropical and
subtropical Queensland. The systems considered were summer crop–winter
fallow, grass or grass–legume pastures for hay production, tobacco,
sugarcane, table grapes, and bananas. Mean acidification rates varied from
-2·4 kmol H+ /ha · year for tobacco to
34·2 kmol H+ /ha · year for bananas.
Acidification rates were higher than for comparable systems in temperate
Australia.
Subsurface acidification occurred under all systems, and was particularly
severe under bananas despite the surface application of at least 2·5 t
lime or dolomite/ha· year. As bananas can be considered to be a
generic perennial horticultural system, subsurface acidification may be a
widespread problem in such systems despite surface applications of amendments.
There was a wide range in acidification rates within a particular agricultural
system, suggesting that management practices can be manipulated to reduce
acidification. As the N cycle terms were the major contributors to the
acidification under cropping systems, N fertiliser management is likely to be
the most critical acidification factor.
Sorption and desorption behaviour of strychnine rodenticide in soils
Authors: Kookana R. S. , Rogers S. L. , Oliver D. P.
Published: August 2004

Strychnine (Strychnidin-10-one) was used as a rodenticide to control a mouse
plague across southern Australia in 1993. Wheat grains were coated with a
mixture (containing strychnine, sugar, flour, oil, and a dye) at a rate of 3 g
strychnine/kg grain, and were spread as a bait for mice at a density of
approximately 3 treated grains/m2. We examined the
release of strychnine residue from the treated grains into soils and its
sorption–desorption behaviour in 4 different South Australian soils,
ranging from sand to clay in texture and acidic to alkaline in reaction.
Release studies using treated grains showed that, unless the treated grains
were buried in soil, the release of strychnine from the treated grain into
soil was slow, requiring about 2 months for its complete transfer into soil.
However, upon burial of the treated grain, such as during resowing, the
transfer of strychnine from the treated grain to soil was rapid
(>90% within 7 days). The sorption of strychnine was found to occur
rapidly (>90% of sorption within 15 min). The sorption affinity of
strychnine varied by almost 1 order of magnitude among the 4 soils studied. An
acidic clay soil (Mintaro) sorbed nearly all (97%) of the applied
strychnine, whereas the alkaline sandy soil (Bute) sorbed only 54% of
the applied amount, when a strychnine solution 10 mg/L was equilibrated
with the soil. Sorption was found to increase substantially with decreasing
pHCa from 9 to 7. Indeed, in the 2 soils with relatively
higher sorption capacities, nearly 100% of the applied strychnine was
sorbed at pHCa 6·5. The pH dependency of sorption
was found to follow the proportion of cationic species of strychnine base
present in the soil solution. During desorption, hysteresis between the
sorption and desorption isotherms of strychnine was noted. The study showed
that except in very sandy, alkaline soils, the sorption of strychnine is
likely to be high.
Quaternary sedimentation, parna, landforms, and soil landscapes of the Wagga Wagga 1 : 100 000 map sheet, south-eastern Australia
Authors: Chen Xiang Yang
Published: August 2004

The Wagga Wagga 1 : 100 000 map sheet is on the Western Slopes of southern New
South Wales. The regional topography changes from hills in the east and
south-east to gently sloping rises and alluvial plains in the west. Aeolian
clays (parna) form a consistent clay regolith regardless of the underlying
geology in the gently sloping areas. In some alluvial plains and on some lower
hill slopes, the surficial sediments contain a significant portion of reworked
parna. In hilly areas, parna is poorly preserved except on some remnant
ancient land surfaces, such as dissected plateaux and piedmont plains.
The soil pattern in the area is well controlled by landform processes and
history. On relatively steep hill slopes, locally derived materials from
weathering of bedrock are usually the dominant components of the soils, and
geology is the dominant factor controlling soil distribution. In contrast, the
Murrumbidgee high floodplain is covered by uniform silty clay with deep clayey
soils (brown/grey Dermosols). Before the mid-Holocene, the alluvium mainly
comprised sands and gravels, which were reworked by wind forming sand sheets
and sand mounds (source-bordering dunes) on which deep sandy soils (Rudosols)
now occur. The sediments and soils on the alluvial plains of local streams
vary according to their distance from the source area and the flooding
frequency. Areas considered to be mantled by parna, uniform red clayey soils
(haplic red Kandosols/Chromosols) occur.
Although the distribution pattern of the soils is controlled by the landform
evolution, the relationships between soil morphological properties and
topography are not readily quantified. On the alluvial and gently sloping
landforms, soil properties usually show little change even though slope
gradient and slope length vary. Some soils, e.g. the Rudosols on the sand
sheets, rarely show any topographic features which may indicate their
presence. In limited areas, e.g. on steeper hills formed on metasedimentary
rock, the soil properties vary with changes in topographic parameters (slope
gradient and slope length).
Structural vulnerability of New Zealand soils
Authors: Hewitt A. E. , Shepherd T. G.
Published: August 2004

Some New Zealand soils withstand intensive cultivation and support continuing
high production and yet maintain essential soil physical qualities of
infiltration, aggregation, and aeration. In other soils, essential soil
qualities deteriorate rapidly under the impact of even moderately intensive
management practices. Our objective was to estimate the inherent
susceptibility of New Zealand soils to physical degradation by focusing on
structural vulnerability. We took a deductive approach by reviewing the
available information on the structural stability and physical degradation of
New Zealand soils. We identified 4 soil attributes that are well represented
in the national soils database and are most likely to control structural
vulnerability: (i) stabilising short-range-order
oxy-hydroxides of aluminium and iron as estimated by phosphate retention,
(ii) total organic carbon content,
(iii) clay content, and (iv)
wetness. The 4 attributes were standardised and transformed and a simple
structural vulnerability index (SV) was devised. We determined SV for all
mineral soils in the national soils database. The results provide a ranking of
soil groups according to their structural vulnerability. We concluded that the
index may be used as a first approximation rating of the structural
vulnerability of New Zealand soils to aid resource management.
Magnesium in tropical and subtropical soils from north-eastern Australia. I. Magnesium fractions and interrelationships with soil properties
Authors: Hailes K. J. , Aitken R. L. , Menzies N. W.
Published: August 2004

The magnesium (Mg) status of 52 highly weathered, predominantly acidic,
surface soils from tropical and subtropical north-eastern Australia was
evaluated in a laboratory study. Soils were selected to represent a range of
soil types and management histories. Exchangeable Mg concentrations were
generally low (median value 0·37 cmol(+)/kg), with deficient
levels (<0·3 cmol(+)/kg) being measured in 22 of the soils,
highlighting the potential for Mg deficiency as a limitation to plant growth
in the region. Furthermore, acid-extractable Mg concentrations, considered a
reserve of potentially available Mg, were generally modest (mean and median
values, 1·6 and 0·40 cmol(+)/kg, respectively). The
total Mg content of the soils studied ranged from 123 to 7894 mg/kg, the
majority present in the mineral pool (mean 71%), with smaller
proportions in the acid-soluble (mean 11%) and exchangeable (mean
17%) pools, and a negligible amount associated with organic matter
(mean 1%).
A range of extractant solutions used to displace exchangeable Mg was compared,
and found to yield similar results on soils with exchangeable Mg <4
cmol(+)/kg. However, at higher exchangeable Mg concentrations, dilute
extractants (0·01 M CaCl2, 0·0125
BaCl2) displaced less Mg than concentrated extractants
(1 M NH4Cl, 1 M NH4OAc, 1 M KCl).
The concentrated extractants displaced similar amounts of Mg, thus the choice
of extractant is not critical, provided the displacing cation is sufficiently
concentrated. Exchangeable Mg was not significantly correlated to organic
carbon (P > 0·05), and only 45% of the
variation in exchangeable Mg could be explained by a combination of
pHw and clay content.
Tree clearing and dryland salinity hazard in the Upper Burdekin Catchment of North Queensland
Authors: Williams John , Bui E. N. , Gardner E. A. , Littleboy Mark , Probert M. E.
Published: August 2004

This paper provides experimental data on the effect of tree clearing,
introduction of perennial Stylosanthes based pastures,
and the use of native grasses on the water balance of a red earth soil in the
Upper Burdekin Catchment near Charters Towers. The water balance simulation
models SWIM and PERFECT are used to extend the results and estimate deep
drainage for this and other soils in this tropical environment. The analysis
illustrates that the soil/climate interaction in the wet/dry tropics
has a similarity with the winter-dominant rainfall zone where vegetation
change can substantially increase deep drainage beyond the root-zone. Salt
distribution in the soil/landscapes of the Upper Burdekin suggests that
there is a salinity hazard, should a significant shift in the water balance
occur as a result of tree clearing. Therefore, in the Upper Burdekin Catchment
of North Queensland, indiscriminate tree clearing is a hazardous form of land
management and should only proceed after the risks of dryland salinity have
been evaluated and shown to be negligible.
TDR estimation of the resident concentration of electrolyte in the soil solution
Authors: Vogeler I. , Clothier B. E. , Green S. R.
Published: August 2004

In order to examine whether the electrolyte concentration in the soil solution
can be estimated by time domain reflectometry (TDR) measured bulk soil
electrical conductivity, column leaching experiments were performed using
undisturbed soil columns during unsaturated steady-state water flow. The
leaching experiments were carried out on 2 soils with contrasting pedological
structure. One was the strongly structured Ramiha silt loam, and the other the
weakly structured Manawatu fine sandy loam. Transport parameters obtained from
the effluent data were used to predict the transient pattern in the resident
electrolyte concentration measured by TDR. The electrolyte concentration was
inferred from the TDR-measured bulk soil electrical conductivity using 2
different calibration approaches: one resulting from continuous solute
application, and the other by direct calibration. Prior to these, calibration
on repacked soil columns related TDR measurements to both the volumetric water
content and the electrolyte concentration that is resident in the soil
solution. The former calibration technique could be used successfully to
describe solute transport in both soils, but without predicting the absolute
levels of solute. The direct calibration method only provided good estimates
of the resident concentration, or electrolyte concentration, in the strongly
structured top layer of the Ramiha soil. This soil possessed no immobile
water. For the less-structured layer of the Ramiha, and the weakly structured
Manawatu soil, only crude approximations of the solute concentration in the
soil were found, with measurement errors of up to 50%. The small-scale
pattern of electrolyte movement of these weakly structured soils appears to be
quite complex.
Discontinuous spectrocolorimetric titration method for determining stability constants of fulvic acid - iron complexes
Authors: Pandeya S. B. , Singh A. K.
Published: August 2004

The stability constants for the complexes formed between iron species existing
in ambient soil environment and fulvic acids (FA) extracted from organic
wastes like sewage sludge, farm yard manure (FYM), poultry manure, and press
mud were determined in aqueous media of pH 5·0 and 8·5 by
discontinuous spectrocolorimetric titration method. The values of stability
constant (log K) of Fe–FA complexes estimated at pH 5·0 were
6·026, 6·212, 6·270, and 6·342 for FYM, sludge,
poultry manure, and press mud, respectively. The respective values at pH
8·5 were 6·145, 6·276, 6·350, and 6·940.
The order of the values of log K for different preparations of fulvic acids
was press mud > poultry manure > sludge > FYM. The functional group
contents, their pH of neutralisation, and electrostatic properties of the FA
such as pKINT, pKm, and
0·868 nW, were found to be the determining factors for maximum binding
ability of FA for metal cations and the stability constant of Fe–FA for
different FA preparations. The basic assumptions and the limitations of the
discontinuous spectrocolorimetric estimation of stability constants for
Fe–FA are discussed.
Soil acidification and the carbon cycle in a cropping soil of north-eastern Victoria
Authors: Slattery W. J. , Edwards D. G. , Bell L. C. , Coventry D. R. , Helyar K. R.
Published: August 2004

Changes in soil organic matter were determined for a long-term (1975–95)
experiment at the Rutherglen Research Institute in north-eastern Victoria. The
crop rotations in this experiment were continuous lupins (LL) and continuous
wheat (WW). The soil at this site was a solodic or Yellow Dermosol with a soil
pH of 6·08 (pH in 0·01 М CaCl2 1 : 5)
in 1975 in the surface 10 cm, which had declined by 0·8 and 1·5
pH units for WW and LL, respectively, in the 0–20 cm soil zone by 1992.
Acidification rates decreased with increasing soil depth. The acidification
rate in the 0–60 cm soil zone was 12·5
kmol(H+)/ha·year for the LL rotation and
4·6 kmol(H+)/ha·year for the WW
rotation. The amount of CaCO3 required to neutralise the
acidification of wheat-lupin rotations as calculated in this paper was up to
3·8 t/ha ·10 years for a WLWL rotation or 3 ·3
t/ha ·10 years for a WWL rotation; these amounts are significantly
higher than previously reported rates.
In this paper, we calculate the impact of changes in soil carbon (C) status
over time, and therefore soil buffering, on the rates of acidification in
incremental soil layers to a depth of 60 cm. Total organic C for these
rotations in 1992 was 1·12% for WW and 1·17% for
LL in the 0–10 cm soil zone. An investigation of the humic and fulvic
acid fractions of these 2 rotations to a depth of 60 cm showed that the LL
rotation had significantly higher (P < 0·05) C
at depth than the WW rotation. Acidification due to the net decrease in soil C
over the 15-year study period plus acidification due to the alkali removed in
the seed was calculated to be –4·88
kmol(H+)/ha·year for the LL rotation and
–6·52 kmol(H+)/ha·year for
the WW rotation.
Is soil an appropriate dumping ground for our wastes?
Authors: Cameron K. C. , Di H. J. , McLaren R. G.
Published: August 2004

New Zealand and Australia generate large quantities of agricultural,
industrial, and municipal wastes. As authorities move to protect the
environment by regulating waste disposal practices, environmentally sound
methods of waste disposal are being sought. In particular, land application of
wastes as a means of disposal, nutrient re-cycling, and water conservation is
becoming increasingly popular.
This paper provides an overview of the types, quantities, and characteristics
of wastes generated in New Zealand and Australia, and highlights the problems
with current waste disposal practices, including landfilling, incineration,
and discharging into waters. This is followed by a detailed review of the
beneficial effects and adverse impacts of land application of wastes on plant
production and soil and environmental quality, and possible hazards to human
health.
The management of waste application on land is a challenging task and requires
rigorous scientific input. Sludges and euents contain significant
concentrations of plant nutrients, particularly nitrogen, phosphorus, and
organic matter. Their application on land has been shown, in many cases, to
result in significant increases in plant yields and improvements in soil
physical conditions and chemical fertility. The constraints with some wastes,
particularly those of industrial and municipal origin, are that they contain
undesirable constituents, e.g. heavy metals, toxic organics, pathogens, and
salts, or have extremely high or low pH. High concentrations of nitrate and
phosphate derived from wastes are also of concern for ground and surface water
contamination. The processes that control the fate of wastes in the soil are
complex and many of them are poorly understood, e.g. rate of release of
nutrients and other chemicals; leaching of nutrients, metals, and organics
through macropores and as suspended solids; emission of greenhouse gases;
impact of solvents, surfactants, and sludge organic matter on the sorption,
degradation, and leaching of hydrophobic organics; and the long-term
bioavailability and fate of metals and organics fixed by soil organic matter.
More research is urgently required to develop a sound understanding of waste
characteristics and the processes affecting their fate in the soil in order to
ensure that land application of wastes is safe.
Competitive exchange of K+ , Na+ , and Ca2+ during transport through soil
Authors: Bond W. J.
Published: August 2004

Competitive exchange affects the transport of cations through soils with
negatively charged surfaces, and when more than 2 cations are present in the
soil solution the effects are complex. There has been little previous
experimental work to examine these effects in ternary (or higher order) cation
systems. Cation transport experiments involving both binary and ternary cation
exchange were therefore carried out. Calcium, which initially saturated both
the solution and exchange phases of the soil, was displaced by infiltrating
solutions of Na+ and
Ca2+, K+ and
Ca2+, or K+ and
Na+. In all cases, the equivalent fraction of
Na+ or K+ in the
inflowing solution was 0·5. The spatial distributions of cation
concentrations in both the solution and exchange phases were measured by
destructive sampling. The Na+ front advanced into
the soil much more rapidly than K+ in all
experiments because
Ca2+–K+ exchange
was much stronger than
Ca2+–Na+ exchange.
In the ternary experiments (Na+ and
K+ displacing Ca2+),
this led to the K+ and
Na+ fronts being distinctly separate from each
other, with the result that
Ca2+–K+ exchange
occurred in a background of almost constant Na+
concentration, and
Ca2+–Na+ exchange
occurred in a background of constant (near-zero) K+
concentration. The presence of the highly competitive
K+ had little influence on the transport of
Na+, but the presence of
Na+ did affect the distribution of
K+. For experiments involving both binary and
ternary exchange, the positions of the cation fronts and the shapes of the
cation distributions in both the solution and exchange phase could be
predicted using the appropriate binary exchange isotherms and approximate
analytical solutions published previously.
The fate and transformations of zinc added to soils
Authors: Ma Y. B. , Uren N. C.
Published: August 2004

A new sequential extraction procedure to remove specifically adsorbed forms of
trace metals and easily reducible manganese (Mn) oxide fractions was used to
study the fate and transformations of zinc (Zn) added to soils. Most of the
endogenous Zn in field soils (75–87%) was found to exist in a
residual fraction which is considered to be silicates, while the Zn added as a
fertiliser in the field soils was found predominantly in an EDTA-extractable
fraction and in association with iron (aluminium) [Fe (Al)] and Mn
oxides. The Zn recently added to soils was found to be more in the reactive
forms (water-soluble plus exchangeable and EDTA-extractable Zn) than the Zn
added to field soils in association with long-term Zn application. With time,
the EDTA-extractable Zn transformed into the unreactive forms (Zn associated
with Fe (Al) and Mn oxides). The processes could be described by a diffusion
equation. The apparent diffusion rate coefficients were found to be in the
order of
10–10–10–11/s.
The diffusion activation energy
(Ea) was found to be 67
kJ/mol. The diffusion of Zn cations into microporous solids is probably a
rate-limiting process. The transformation of reactive Zn into unreactive Zn
was enhanced by elevated temperatures and by drying and rewetting. The drying
and rewetting effect at relatively high temperature may be important in the
processes which lead to decreases in the availability of Zn to plants.
Transformation and degradation of fenamiphos nematicide and its metabolites in soils
Authors: Kookana Rai S. , Phang C. , Aylmore L. A. G.
Published: August 2004

Fenamiphos is an important nematicide{insecticide and commonly used in
horticultural crops and turfs in Australia. We studied the
transformation/degradation of fenamiphos under controlled conditions, in
surface and subsurface soils from the Swan Coastal Plain of Western Australia.
In the sandy surface soil, fenamiphos (Fen) was rapidly
oxidised to its sulfoxide (FenSO) analogue. Further
oxidation of FenSO to sulfone
(FenSO2), however, was found to be
very slow, resulting in an accumulation of FenSO. Little
accumulation of FenSO2 occurred
during the study period (139 days). The time taken for 50% loss of the
total residue of fenamiphos
(Fen+FenSO+FenSO2)
was found to be approximately 50 days in the surface soil and about 140 days
in the subsurface soil. Simulations using the LEACHM model showed that the
rate of transformation of Fen to FenSO in the surface
soil (k1 =
0·5/day) was 100 times faster than that of
FenSO to
FenSO2
(k2 =
0·005/day). In the subsurface soil, the difference between the 2
oxidation steps was much smaller (4-fold). The conversion of
Fen to FenSO was much faster in
the surface soil (k1 =
0·5/day) than the subsurface soil
(k1 = 0·02/day).
The observed differences in transformation behaviour of
Fen between the surface and subsurface layers of soil
appear to be associated with the differences in the microbial biomass and the
organic matter contents of the soils. The slower transformation of
Fen in the subsurface soils can have major implications
on its potential for groundwater contamination in vulnerable areas, such as
the Swan Coastal Plain of Western Australia.
Dynamics of organic matter in soil as determined by variations in 13C/12C isotopic ratios and fractionation by ease of oxidation
Authors: Conteh A. , Lefroy R. D. B. , Blair G. J.
Published: August 2004

Management of organic matter in soils requires techniques that accurately
monitor changes in soil organic matter over the short term and long term. This
study was carried out in a glasshouse pot experiment to examine changes in
soil carbon under the influence of long-term cropping, plant residue, and
fertiliser application, using variations in
13C/12C isotopic ratios of
organic materials and fractionation by ease of oxidation. The study examines
the changes in carbon contents of adjacent soil samples with different
cropping histories as affected by application of fertiliser and crop residue
and the growth of wheat. Significant increases in soil carbon values were
observed with residue application. The effects of the applied fertiliser on
soil carbon levels depend on the presence or absence of wheat. A higher amount
of labile carbon was found in the native soil than in cultivated soil.
Natural enrichment of topsoils with chromium and other heavy metals, Port Macquarie, New South Wales, Australia
Authors: Lottermoser Bernd G.
Published: August 2004

Total heavy metal concentrations [cobalt (Co), chromium (Cr), copper(Cu), iron (Fe), mangnese (Mn), nickel (Ni), lead (Pb), and zinc (Zn)]were determined in surface soil samples from Port Macquarie, New South Wales,Australia. Composite topsoil samples (0–10 cm depth) had mean values(per kg) of 13 mg Co, 1020 mg Cr, 59 mg Cu, 136·7 g Fe, 719 mg Mn, 149mg Ni, 20 mg Pb, and 47 mg Zn. The topsoils were generally characterised by alow pH (3·8–5·2) and a mineralogy dominated by haematite,magnetite, quartz, and kaolinite. Chromium was predominantly present in thetopsoils as Cr3+ in microcrystalline chromite(FeCr2O4) and, to a lesser degree,in kaolinite and haematite. Differences in Cr soil concentrations with depthwere due to variations in the relative abundance of the various soilcomponents, rather than Cr3+ mobility within the soilprofile. The elevated heavy metal concentrations are the result of soildevelopment over metal-rich bedrock (serpentinite matrix melange) andassociated enrichment of relatively immobile elements (Cr, Fe, Ni) in theresidual soil profile. The ANZECC and NH&MRC (Australian and New ZealandEnvironment and Conservation Council and National Health & MedicalResearch Council) environmental investigation limits were exceeded for100% of the sample sites for Cr, 47% for Cu, 61% for Mn,and 58% for Ni.