bluuebunny/crossref_metadata_2025 huggingface dataset:
Recropping intervals for sulfonylurea herbicides are short in the semi-arid subtropics of Australia
Authors: Walker S. R. , Osten V. A.
Published: August 2004

Summary. Chlorsulfuron, triasulfuron and metsulfuron
methyl were applied at recommended and double recommended rates in 5 trials
(1990–96) in winter (May–July) or late spring (October) to a heavy
textured soil in the Central Highlands of the north-east grain region of
Australia. Treated areas were sown back to sorghum in the following spring, to
sorghum and sunflower in summer, and to chickpea in the following autumn.
Shoot dry matter at 3 weeks after emergence and grain yields were measured.
Soil residue levels of chlorsulfuron were measured by bioassay following
herbicide application and at sowing of sorghum and chickpea. Rainfall and
temperature were recorded for each fallow period. The recropping intervals
ranged from 2.5 to 4.1 months for spring sorghum, 2.5 to 9.3 months for summer
sorghum and sunflower, and 5.7 to 11.7 months for chickpea. The shorter
intervals were a consequence of the late spring applications. The spring
sorghum crops were significantly injured by all herbicides, when chlorsulfuron
residues at sowing ranged from 1.67 to 2.1 ng/g in the surface 15 cm.
Summer sorghum, sunflower and chickpea were unaffected by any herbicide
treatment, except the covered (rainfall excluded) metsulfuron methyl
treatment. Despite the differences in recropping intervals and fallow rain,
all summer sorghum crops were sown into low chlorsulfuron residues (ranged
from non-detectable to 0.2 ng/g). Similarly, residues measured at chickpea
sowing ranged from non-detectable to 0.1 ng/g. The lack of crop response
and the low levels of detected herbicide residue indicate that in this
environment these herbicides dissipate rapidly, and the safe recropping
intervals are much shorter than currently recommended on herbicide labels.
Liveweight gains, and carcass and meat characteristicsof entire, surgically spayed or immunologically spayed beef heifers
Authors: Jeffery M. , Loxton I. , Mark S. Van der , Bell K. , James T. , Shorthose R. , D'Occhio M.
Published: August 2004

Summary. Growth, carcass and meat characteristics,
market suitability and economic return were compared in surgically spayed
(SS), immunologically spayed (IS) and entire (E) heifers. Spaying had no
effect on daily weight gains of heifers up to 8 weeks following spaying.
Between spaying at 15 months of age, and slaughter at 30 months of age, growth
was greater for E heifers (0.36 kg/day) than for SS heifers (0.32
kg/day) (P<0.01) and for IS heifers (0.33
kg/day) (P<0.05). There was no difference in
growth between SS and IS heifers. Carcass weights at slaughter were: E, 246
kg; SS, 239 kg; IS 240 kg (P>0.05). Other carcass
attributes (meat and fat colour, texture and marbling) were similar for the 3
treatments.
Subcutaneous rump fat depth (P8 site) was similar for the 3 groups (E, 20 mm;
SS, 21 mm; IS, 19 mm) and the percentages of carcasses that had rump fat
depths between 6 and 22 mm were: E, 72%; SS, 66%; IS, 83%
(P>0.05). All other carcasses had fat depths greater
than 22 mm.
Warner-Bratzler initial yield and peak force values of striploin
(Longissimus dorsi) samples were lower
(P<0.05) in the SS treatment than both E and IS
treatments, whereas Instron compression values from the E striploin were lower
(P<0.05) than for both the SS and IS treatments.
There were no differences between treatments in any meat attributes measured
from the eye round (Semitendinosus).
Entire heifers ($A522) realised a higher
(P<0.05) carcass value than SS heifers ($495)
whilst IS heifers ($503) did not differ
(P>0.05) from E and SS heifers. Direct costs of the
spaying treatments (SS, $2.50 per head; IS, 4 vaccinations at
$5.50 each) increased the difference relative to E heifers to
$29.50 (SS) and $41 (IS) per head.
Sap flow, leaf gas exchange and chlorophyll fluorescence of container-grown cashew (Anacardium occidentale L.) trees subjected to repeated cycles of soil drying
Authors: Blaikie S. J. , Chacko E. K.
Published: August 2004

Summary. Cashew
(Anacardium occidentale L.) is an emerging horticultural
crop in tropical northern Australia. Supplementary watering is required during
the dry season to achieve high yields but irrigation guidelines are not well
defined. As an introduction to large-scale field experiments which will aim to
define the irrigation requirements for cashew, this experiment was conducted
on small, container-grown cashew trees to examine their response to drying
soil and to evaluate a range of techniques for measuring tree water use and
photosynthesis with possible application in the proposed field experiments.
Measurements of sap flow, leaf chlorophyll fluorescence and leaf gas exchange
were made on all trees throughout the experimental period.
The water use of trees in drying soil was measured using Granier’s sap
flow system. Sap flux density (L/dm2 sapwood area .
h) of drying trees declined progressively over a 4-day period to a minimum
level that was only 10% of the sap flow in the well watered trees.
Measurements of leaf gas exchange showed similarly large reductions in
photosynthesis and transpiration which were associated with a low (0.05
mol/m2 . s) stomatal conductance in the drying
trees. After rewatering, sap flow and leaf gas exchange recovered to the high
levels of the well watered trees over 3–4 days. Similar behaviour was
observed during the second drying period. Measurements of the ratio of
variable to maximum fluorescence,
Fv :
Fm, an indicator of
photoinhibition, were made on dark-adapted leaves before dawn and during the
day. Fv :
Fm was in the range
0.65–0.80 with no large or sustained differences between drying and well
watered trees. When stomatal conductance and net photosynthetic rate
progressively declined during the period following irrigation, the quantum
yield of photochemical energy conversion in photosystem II,
ΦPSII, remained almost
constant. It is possible that by providing a pathway for electron flow as an
alternative to CO2 assimilation during this period,
photorespiration played an important role in avoiding photoinhibition.
Using soil and plant analyses in decisions about fertilisers: a farmer’s perspective
Authors: Gibson W. R.
Published: August 2004

Summary. This paper describes the part played by soil
and plant analysis in decisions about fertilisers used on a mixed pastoral and
cropping farm at Scone, in the Northern Midlands of Tasmania. Measurements of
phosphorus and potassium concentrations in soils provide an essential
framework for choosing fertilisers for crops and pastures. Use of lime with
certain crops is determined by pH measurements. Neither soil nor plant
analysis are used in choosing nitrogenous fertilisers.
Fifteen paddocks were tested 7–8 years after initial soil tests (Colwell
extracts). Phosphorus concentrations (mean ± s.e.) had risen by 13
± 5 µg/g (P<0.05) and potassium by
89 ± 19 µg/g (P<0.001). In addition,
the relationship between changes in these concentrations and the total
phosphorus or potassium applied to individual paddocks was examined.
Phosphorus concentration rose (P<0.001) by 5.9
µg/g for each 10 kg/ha additional phosphorus applied over the
7–8 years. Application of phosphorus at 7 kg/ha annually was enough
to maintain soil phosphorus levels. No such relationship was detected for
potassium. Application of lime at 4 t/ha raised the pH by about 1 unit.
These results provide some reassurance about the behaviour of soils on Scone
in response to the practices used in commercial mixed farming.
The importance for the farmer of analyses being reliable is stressed, as is
the need for well-based interpretation of the analytical results in order that
the yield responses to fertilisers can be foreseen. Evidence about the
financial returns produced by the increased yields is often lacking,
especially for grazing enterprises.
Soil-extractable sulfur and pasture response to applied sulfur
Authors: Anderson G. C. , Lefroy R. D. B. , Blair G. J.
Published: August 2004

Summary. A glasshouse experiment was conducted to study
the correlation between various soil sulfur (S) extractants and pasture
response to applied S grown under controlled environmental conditions
(glasshouse) as influenced by variations in levels of extractable S.
Intact paired soil cores were collected at 2-month intervals from an S x P
factorial experiment at 4 field sites on the Northern Tablelands of New South
Wales on 11 occasions. Soil samples were collected from each core and the
cores placed in the glasshouse. Sulfur was applied to one core of each pair
and basal nutrients applied to all cores which were then oversown with white
clover (Trifolium repens L. cv. Haifa). The extractable
S in the soil was analysed using the following techniques: 0.1 mol
Ca(H2PO4)2/L
(MCPt); 0.1 mol
Ca(H2PO4)2/L,
treated with activated charcoal (MCPi); water
(H2O); 0.25 mol KCl/L, heated at 40°C for 3 h
(KCl-40); 0.25 mol KCl/L, heated at 100°C for 4 h (KCl-100); 0.5 mol
NaHCO3/L (NaHCO3); and an acid
digestion of the soil (total). Dry matter yield and S content of the pasture
shoots were measured for each 2-month growth period.
The relationship between the various soil S extraction techniques and the
response of pasture to applied S varied over time and was influenced by the
level of inorganic S present in the soil and the amount of organic S
extracted. When the level of MCPi-extractable S ranged
between 2 and 22 µg S/g soil due to the application of fertiliser
(summer 1987–88 and autumn 1988), or after a period of high
mineralisation rates (spring 1988), the MCPi,
MCPt, H2O and KCl-40 techniques
had the highest correlation with the increase in S content of the pasture when
S was applied. The higher correlation for the MCPt,
H2O and KCl-40 techniques than the
MCPi technique indicates that plants obtained some S
from the organic S pool. In contrast, when the levels of
MCPi-extractable S ranged between 2 and 10 µg
S/g soil and the rate of mineralisation increased in response to an
increase in soil temperature (June 1988 and June 1989) or moisture (September
1989) upon transfer of samples from the field to the glasshouse, the
MCPt, H2O and KCl-40 techniques
underestimated the available S pool and had lower
r2 values than either the KCl-100
or NaHCO3 techniques.
Dissolution rates of selected Australian gypsum sources
Authors: Noble A. D. , Randall P. J.
Published: August 2004

Summary. Six samples of gypsum (2 mined materials, 3
from industrial by-products and analytical grade gypsum for comparison) were
evaluated for their rates of dissolution. The rate of dissolution of gypsum
and the subsequent movement of dissolved ions away from the site of
dissolution determine the effectiveness of gypsum as a soil amendment.
Compressed pellets were produced with similar surface areas and densities and
their rates of dissolution assessed using electrical conductivity measurements
of a stirred solution in which the pellets were suspended in a perforated
nylon container. The rate of dissolution was significantly slower in the mined
material and in one of the phosphogypsum samples when compared with the other
sources of gypsum. Scanning electron microscopy of phosphogypsum samples
exhibiting different dissolution rates suggest that these differences may in
part be attributed to the average size and morphology of the gypsum
crystallites. It is suggested that the internal surface area is smaller in the
case of the least soluble industrial gypsum and consequently its rate of
dissolution is reduced. These observed differences in dissolution rates would
affect the efficacy of these materials in reducing clay dispersion and
improving hydraulic conductivity of soils, and should therefore be taken into
account when assessing a particular product for a specific agricultural use.
High performance liquid chromatography determined alkamide levels in Australian-grown Echinacea spp
Authors: Rogers K. L. , Grice I. D. , Mitchell C. J. , Griffiths L. R.
Published: August 2004

Summary. Extracts of Echinacea
spp. are widely used as therapeutic immunostimulants with such activity being
attributed in part to the alkamide fractions of these plants. Using high
performance liquid chromatography, the levels of 8 alkamides, including 2
tetraene alkamides (dodeca-2E, 4E, 8Z, 10E/Z-tetraenoic acid
isobutylamide), were quantitatively determined in 2 Australian-grown
Echinacea spp. Overall, the levels of alkamides in
Australian-grown E. angustifolia were found to be
comparable with levels obtained in this study and other studies for USA and
European Echinacea spp. However, results obtained for
one sample of E. angustifolia suggested that it may have
been mislabelled and that it was most likely a sample of
E. pallida. Levels of tetraene alkamides in
Australian-grown E. purpurea were also similar to, if
not higher, than levels which have been reported for the same species grown in
Germany and the USA. Preliminary studies on the stability of alkamide
compounds in E. angustifolia indicated that they are
susceptible to degradation, with a 13% loss of alkamide level over 2
months. Overall, results indicate that there is considerable potential to
develop Echinacea as a viable crop in Australia.
Aqueous chemistry of major ions and trace metals in the Takaka - Cobb River system, New Zealand
Authors: Kim Jonathan P. , Hunter Keith A.
Published: August 2004

Concentrations of major ions (Na+,
K+, Ca2+,
Mg2+, Cl-, SO 4 2–), total
alkalinity (TA), silicate (Si) and trace metals (Zn, Cu, Pb, Cd) have been
investigated in the Takaka–Cobb River system at the northernmost
extremity of the South Island, New Zealand. The range in concentrations of
major ions, Si and TAwas large, with Ca2+ and
TAdominating. Some waters in the upper catchment were close to saturation with
respect to calcite, reflecting limestone dissolution both in the upper Takaka
River and in an associated spring system.
Dissolved trace metals exhibited different behaviour, with constant or
increasing concentrations upriver, especially in the Cobb Valley. Low
concentrations found in the upper Takaka River suggest that limestone
weathering makes a minor contribution to concentrations of trace metals. The
Cobb River exhibited much higher concentrations, implying that the differing
compositions of rock types and soils within the separate catchments exercise
important controls on trace metals.
Stock assessment and risk analysis for the school shark (Galeorhinus galeus) off southern Australia
Authors: Punt André E. , Walker Terence I.
Published: August 2004

A spatially aggregated age- and sex-structured population dynamics model was
fitted to standardized catch-rate data from the school shark resource off
southern Australia. The model incorporates the peculiarities of shark
populations and fisheries, including the pupping process and the selectivity
characteristics of gill-nets. Estimates are determined by a Bayesian approach
that incorporates prior distributions for virgin biomass, the parameter that
determines productivity, and the variation in pup survival. Tests of
sensitivity include changing the data series used, varying the value of adult
natural mortality, and changing the prior distribution for the productivity
parameter. The point estimates of the mature biomass at the start of 1995
range from 13% to 45% of the pre-exploitation equilibrium size,
depending on the specifications of the assessment. The results are notably
sensitive to the selection of a catch-rate series. Results suggest that the
current fishing intensity will lead to further declines in abundance, that a
reduction of ~20% in fishing mortality would achieve a 0.5 probability
of not declining further, and that a reduction of 42% would achieve
with a probability of 0.8 the management goal of not being below the 1996
mature biomass at the start of 2011.
Extra keyword: CPUE.
Spatial patterns in estuarine fish faunas in tropical Queensland: a reflection of interaction between long-term physical and biological processes?
Authors: Sheaves Marcus
Published: August 2004

Spatial differences in the distribution and abundance of fish faunas of
structurally complex habitats in subtidal areas of three tropical estuaries
were investigated by using modified Antillean-Z fish traps. The overall
species compositions of the three estuaries were similar; however, the
distribution and abundance of species differed substantially both within and
among estuaries. Although the abundance of most species declined in an
upstream direction, the fish assemblages of upstream areas of different
estuaries were similar. In contrast, assemblages in seaward regions were quite
distinct. Neither temperature nor turbidity were correlated with catch rates
of the most abundant species. Although catch rates of some species were
significantly correlated with deviation away from normal seawater salinity, in
most cases the correlation with maximum deviation in salinity was much
stronger. Thus, decreased catches and the absence of some common species from
upstream areas may be related to the influence of long-term (months and years)
patterns of salinity. Some species were abundant only in one region of a
single creek. This may reflect the close proximity of nearby habitats from
which recruits may come.
Reproductive biology of the whiskery shark, Furgaleus macki, off south-western Australia
Authors: Simpfendorfer Colin A. , Unsworth Philip
Published: August 2004

The whiskery shark, Furgaleus macki, is important in the
commercial shark fishery off southern Western Australia. The reproductive
biology was studied with the aid of 88 specimens collected by commercial
gill-net vessels off south-western Australia between March 1994 and August
1996. The size selectivity of the gill-nets resulted in only mature and large
juvenile specimens being caught. Size at birth was estimated to be 22–27
cm total length. Size (fork length) at maturity was 107 cm for males and 112
cm for females. There is a seasonal reproductive cycle. Mating is most likely
to occur from August to September, with females storing spermatozoa until
ovulation in late January to early April. Gestation lasts 7–9 months,
with parturition from August to October. Litter sizes vary from 4 to 28 (mean
19). There was a significant linear relationship between litter size and
maternal length. Mature males mate each year, but females produce litters
every second year. Mature non-pregnant females develop large yolky ova from
March to October, with development of the ova completed several months before
ovulation. The results are compared with previous records and with data for
other species of the family Triakidae that occur off southern Australia.
A water budget and hydrology model of a basin mangrove forest in Rookery Bay, Florida
Authors: Twilley Robert R. , Chen Ronghua
Published: August 2004

Water budgets of two basin mangrove forests in Rookery Bay were determined by
measuring during a 2-year period the inputs of precipitation and tides,
together with losses through seepage, runoff and evapotranspiration.
Precipitation inputs to the forest floor were 75.1% from throughfall
and 19% from stemflow for a total of 1097 mm
year-1, or 91% of annual rainfall. Runoff was
estimated at 896 mm year-1, or nearly 77% of the
combined input of throughfall and stemflow. Loss from evapotranspiration was
linear with saturation deficit of the atmosphere and was 967 mm
year-1 (0.7–4.5 mm day-1).
Loss from horizontal flow of groundwater in shallow mangrove soils was ~285 mm
year-1. Frequency of tidal inundation was seasonal,
ranging from <5 tides month-1 in February to 30 tides
month-1 in September. Tides recharged soil saturation
deficits, the cumulative tidal input being 12 276 mm
year-1 and efflux being 11767 mm
year-1. The relative significance of tides and rainfall
deficits (rainfall – evapotranspiration) on the seasonal patterns of
soil saturation (water levels) and soil salinity were simulated with a
finite-difference hydrology model (HYMAN). Model simulations demonstrate that
soil salinity at higher elevations in the intertidal zone, where tidal
inundation frequency is reduced, is more sensitive to changes in rainfall
deficit.
Reproductive biology of shortnose spiny dogfish, Squalus megalops, from the Agulhas Bank, South Africa
Authors: Watson G. , Smale M. J.
Published: August 2004

Aspects of the reproductive biology of Squalus megalops
were investigated in material collected from commercial and research trawl
samples from the Agulhas Bank. The largest male measured 572 mm TL and the
largest female 782 mm. The size at which 50% of the males in the
population were sexually mature was ~400 mm; 50% of the females were
mature at ~500 mm, and 50% were pregnant at ~510 mm. Litter size varied
from 2 to 4 but only the largest females had the maximum litter size.
Reproduction in S. megalops is aplacental-viviparous,
and the pups are 232–277 mm at birth. The sex ratio of embryos was not
significantly different from unity. Trawled dogfish had a sex ratio
significantly different from unity, probably because of sampling bias;
aggregations were apparently not adequately sampled over their entire
distribution.
Population structure of the Australian gummy shark (Mustelus antarcticus GÜnther) inferred from allozymes, mitochondrial DNA and vertebrae counts
Authors: Gardner M. G. , Ward R. D.
Published: August 2004

The gummy shark (Mustelus antarcticus) is the main
target of southern Australian shark fisheries. Its stock structure was
investigated through allozymes (up to 28 loci), mitochondrial DNA (up to 10
restriction enzymes) and vertebrae counts. The average heterozygosity per
allozyme locus (0.099) and degree of polymorphism (0.255) was high for sharks.
Composite mitochondrial DNA haplotype diversity (0.534) and mean nucleotide
sequence diversity (0.16%) were also moderately high. Three of the
seven polymorphic allozyme loci (CK-A*,
LDH-1*, PEP*) and the
mtDNA haplotypes showed significant spatial differentiation. Two genetic
stocks were identified: one along the southern coast of Australia from Bunbury
in Western Australia to Eden in New South Wales and one off northern New South
Wales (in the region of Newcastle to Clarence River). There was some evidence
for a third stock off Townsville, Queensland. The northern occurrences extend
the known geographical range of this species. Vertebrae counts from Eden
northwards increased, supporting the conclusion of population heterogeneity
off eastern Australia.
Expression of pigmentation genes and photo-regulation of anthocyanin biosynthesis in developing Royal Gala apple flowers
Authors: Dong Yi-Hu , Beuning Lesley , Davies Kevin , Mitra Deepali , Morris Bret , Kootstra Arend
Published: August 2004

Anthocyanin levels and the expression of six genes involved in anthocyanin
biosynthesis (PAL, CHS,
CHI, F3H,
DFRand ANS) were studied during
apple (Malus domestica Borkh.) flower development. In
the petal, maximal accumulation of the six mRNAs occurred at an early stage of
flower development and then declined rapidly following petal expansion. During
petal development, the highest levels of CHI enzymatic activity and
anthocyanin concentration appeared about one day after maximum mRNA levels of
the six genes. Blocking UV or natural light (dark treatment) before flower bud
break reduced the expression of the six genes and inhibited anthocyanin
biosynthesis, resulting in either pink (UV block treatment) or pure white
(dark treatment) apple flowers. Furthermore, the pure white flowers (dark
treatment) were unable to resynthesise anthocyanins, even if they were
re-exposed to light or placed under UV-B plus white light
in vitrofollowing stage I of flower development. These
results suggest that anthocyanin biosynthesis and the activities of these
genes in the developing apple flower are controlled by both development and
light and that the key stage for the photoregulation is during the early
stages of development.
Salinity effect on bioelectric activity, growth, Na+ accumulation and chlorophyll fluorescence of maize leaves: a comparative survey and prospects for screening
Authors: Shabala Sergey N. , Shabala Svetlana I. , Martynenko Alexey I. , Babourina Olga , Newman Ian A.
Published: August 2004

Changes in the bioelectric activity of maize leaves caused by a single light
pulse (6 s; 70 mol m-2 s-1) were
used to compare the effects of NaCl treatment (20–200 mM) on plant
growth, Na+ accumulation in leaves, chlorophyll
fluorescence and pigment composition. Bioelectric responses seemed to be the
most sensitive indicator of NaCl effects. Even the weakest salt treatment (20
mM) caused a statistically significant decrease (about 40%) in the
amplitude of the bioelectric response. The higher the NaCl concentration, the
smaller was the amplitude. Over the full concentration range, the
characteristic time of response increased from about 30 to 60 sec, indicating
that the rate of bioelectric changes was slowed by increasing salinity.
Other reliable characteristics were found to be the fluorescence yield and
quenching coefficients. The
Fv/Fm
ratio was not significantly affected by NaCl treatment. Changes in growth
rate, biomass or pigment composition were either insensitive, or showed a
plateau over a wide range of NaCl concentrations, and were inappropriate for
screening. A possible link between bioelectric and fluorescence
characteristics is discussed. We conclude that leaf bioelectric activity can
be used together with, or instead of, chlorophyll fluorescence measurements,
to screen genotypes for salt tolerance.
Nitrogen deficiency precludes a growth response to CO2 enrichment in C3 and C4 Panicum grasses
Authors: Ghannoum Oula , Conroy Jann P.
Published: August 2004

We investigated the interaction of nitrogen (N) supply and
CO2 enrichment on the growth and photosynthesis of
Panicum laxum (C3),
P. coloratum (C4) and
P. antidotale (C4). Plants were
grown at ambient CO2 partial pressures
(pa) of either 36 (low) or 71
(high) Pa, in potted soil supplied with 0 (low) or 60 (high) mg N
kg-1 soil week-1. Elevated
CO2 enhanced total plant dry mass of all three species
by approximately 28% under high N supply, but had no effect on biomass
accumulation under N deficiency. CO2 enrichment resulted
in reductions of CO2 assimilation rates
(A; measured at comparable
pa) of
P. laxum, indicating acclimation of photosynthesis. This
acclimation, which was more pronounced under N stress, was unrelated to
changes in leaf N or non-structural carbohydrate concentrations, because
neither were affected by CO2 enrichment. In the
C4 grasses grown at low N, A were
fully saturated at the current ambient
pa, whereas at high N,
A increased slightly when CO2 was
raised to 71 Pa. N deficiency reduced the initial slope of the
CO2 response curve of A in
P. antidotale, and this effect was more pronounced at
high CO2. In conclusion, the preclusion of a growth
response to CO2 enrichment by N deficiency was
correlated with a strong inhibition of A in the
C3 species, and the saturation of
A at below current atmospheric
pa in C4
species.
Runooff ratio as a factor in the empirical modelling of soil erosion by individual rainstorms
Authors: Kinnell P. I. A.
Published: August 2004

A number of factors that influence erosion have separate and differing effects
on flow discharge and sediment concentration, depending on local conditions.
Empirical erosion models that do not have mechanisms to help account for these
separate and differing effects often lack the capacity to predict event
erosion adequately in many locations. In this paper, the product of the
EI30 index, the erosivity index used in the Universal
Soil Loss Equation (USLE) and the revised version (RUSLE), and the runoff
ratio (QR) is discussed in
relation to its capacity to act as an event erosivity index where sheet and
rill erosion occur either separately or together in a rainstorm. An analysis
of runoff and soil loss data shows the index to be superior to the
EI30 index as an event erosivity index for storms on
bare fallow plots at Holly Springs, Mississippi. The inclusion of runoff as an
independent term in the USLE/RUSLE results in a need to determine new
values for the soil erodibility factor, K. Existing
USLE/RUSLE equations for determining L and
S (topographic factors), C (a crop
and crop management factor), and P (an erosion control
practice factor) may be used as first approximations provided that the values
of the new index are determined for the unit plot condition. Since many of the
factors that determine L, S,
C, and P influence runoff, new
methods to determine these parameters need to be developed in the future if
the new index is to be used most effectively.
Macro-aggregation of soils by biological bonding and binding mechanisms and the factors affecting these: a review
Authors: Degens B. P.
Published: August 2004

This review presents an analysis of the labile bonding (organic compounds) and
binding (hyphae and roots) mechanisms involved in stabilising soil into
macro-aggregates in soils (aggregates >0 · 25 mm diameter). The main
emphasis is on the approaches used to study these mechanisms and the factors
that affect the aggregating mechanisms at the micro-scale
(<100µm) level in soils. Much of the
understanding of the stabilisation of soil into macro-aggregates in field
soils by labile organic C is derived primarily from the interpretations of
studies where soils were incubated under artificial conditions. In addition,
many recent studies have assessed the importance of labile organic C in
macro-aggregation based only on whole soils analyses of hyphal length,
extractable carbohydrate C, microbial biomass C, or aliphatic C. These
approaches have contributed little to understanding fundamental factors that
can influence the biological mechanisms of macro-aggregation under field
conditions. It is proposed that greater consideration of bonding and binding
aggregation mechanisms and the factors affecting the mechanisms at the
micro-scale level will facilitate development of field management practices
that benefit macro-aggregation. Factors influencing the location and
persistence of bonding and binding mechanisms in the soil matrix are
discussed.
Long-term phosphorus trends in Vertisols under continuous cereal cropping
Authors: Dalal R. C.
Published: August 2004

Vertisols originally carrying brigalow vegetation
(Acacia harpophylla F. Muell. ex Benth.) and cultivated
for cereal cropping for up to 45 years were examined for trends in available
phosphorus (P) [sodium bicarbonate extractable P (bicarb. P) and dilute
acid extractable P (acid P)], organic P, inorganic P, and total P. The
soils (0-0 · 1 m depth) in their virgin state contained 60 mg/kg of
bicarb. P, 168 mg/kg of acid P, 239 mg/kg of organic P, and 330
mg/kg of inorganic P. All fractions of soil P declined following
first-order decay with the period of cereal cropping; the rates of bicarb. P
and acid P (available P) decline were 0 · 047 and 0 ·
08/year. The organic P, inorganic P, and total P declined more slowly than
available P; the respective rates were 0 · 026, 0 · 019, and 0
· 021/year. The rates of loss of total P and inorganic P were much
higher from the clay-size fraction than the silt-size or sand-size fraction,
with the t½ value of
inorganic P in the sand-size fraction being almost 20 times greater than any
other fraction. On the other hand, organic P loss from the clay-size fraction
was much less; presumably, clay provides physical protection to soil organic
matter and hence to organic P from decomposition. On average, bicarb. P and
acid P declined at the rate of 1 · 3±0 · 3 and 4 ·
6±1 · 4 mg P/kg soil · year. The declines in organic
P and inorganic P were 3 · 0±0.4 and 4 · 1±1
· 2 mg P/kg soil · year, with a loss in total P of 7
· 2±1 · 3 mg P/kg soil · year. There was no
significant shift in the ratio organic P: total P (38±7%) with
the period of cultivation and cereal cropping. Organic P was closely
correlated with organic C and total N in these soils.
The mean amounts of P contained in the grain and the dry matter of each cereal
crop from 1981 and 1984 were 7 · 6±1 · 8 and 8 ·
3±2 · 4 kg P/ha, respectively. Thus, most of the soil total
P loss could be accounted for by crop removal, of which organic P contributed
about 40%. However, the continuous decline in available P, especially
below 15 mg P/kg soil, warrants remedial measures to arrest the decline in
the yields of crops grown on these Vertisols.
Improving the field estimation of saturated hydraulic conductivity in soil survey
Authors: McKenzie Neil , Jacquier David
Published: August 2004

Prediction of the movement and storage of water in soil is central to
quantitative land evaluation. However, spatial and temporal predictions have
not been provided by most Australian soil surveys. The saturated hydraulic
conductivity (Ks) is an essential
parameter for description of water movement in soil and its estimation has
been considered too difficult for logistic and technical reasons. The
Ks cannot be measured everywhere
and relationships with readily observed morphological variables have to be
established. However, conventional morphology by itself is a poor predictor of
Ks. We have developed a more
functional set of morphological descriptors better suited to the prediction of
Ks. The descriptors can be applied
at several levels of detail.
Measurements of functional morphology and
Ks were made on 99 horizons from
36 sites across south-eastern Australia. Useful predictions of
Ks were possible using field
texture, grade of structure, areal porosity, bulk density, dispersion index,
and horizon type. A simple visual estimate of areal porosity was satisfactory,
although a more quantitative system of measurement provided only slightly
better predictions. Regression trees gave more plausible predictive models
than standard multiple regressions because they provided a realistic portrayal
of the non-additive and conditional nature of the relationships between
morphology and Ks.
The results are encouraging and indicate that coarse-level prediction of
Ks is possible in routine soil
survey. Direct measurement of Ks
does not appear to be generally feasible because of the high cost, dynamic
nature of Ks, and substantial
short-range variation in the field. Prediction is further constrained by the
limited returns from more sophisticated morphological predictors. The degree
to which this limits practical land evaluation is yet to be demonstrated.
Effects of sodium accumulation on soil physical properties under an effluent-irrigated plantation
Authors: Balks M. R. , Bond W. J. , Smith C. J.
Published: August 2004

Effluent irrigation commonly results in increased soil sodicity, because of
the medium-to-high salinity and high sodium concentrations of many effluents.
The exchangeable sodium percentage (ESP) of soils at the Wagga Wagga Effluent
Plantation Project increased from <2% to >25% at some
depths within the surface 0·6 m of soil, after 5 seasons of irrigation
with either (i) treated sewage effluent or
(ii) bore water with similar salinity and sodium
adsorption ratio (SAR). A survey of dispersion index (DI) and saturated
hydraulic conductivity (Ksat) was
carried out to investigate the effects of increased soil sodicity on soil
physical properties. The Ksat was
measured after 5 irrigation seasons at 2 depth intervals
(0·15-0·45 m and 0·5-0·8 m) using both bore water
and distilled water, and compared with measurements made at the same sites
using bore water before irrigation commenced. Both DI and ESP were measured at
each of 3 depths in the surface 0·6 m of soil. The DI in distilled
water was positively correlated with ESP, with finer soil textures having
higher DI for the same ESP. When measured in bore water or effluent, DI was
very low and not related to ESP.
Ksat was significantly lower after
5 irrigation seasons, and significantly lower in distilled water than in bore
water. However, there was no relationship between
Ksat and ESP. It was concluded
that the increased ESP caused an increased tendency for soil dispersion but
was not shown unequivocally to lead to decreased
Ksat. The increased sodicity does
not seem likely to affect continued use of the land for effluent irrigation,
but may affect its suitability for alternative uses that involve physical
disturbance of the soil, for example, by cultivation.
Relationships of water repellency to soil properties for different spatial scales of study
Authors: McKissock I. , Gilkes R. J. , Harper R. J. , Carter D. J.
Published: August 2004

In order to predict the occurrence of water repellency, which is a labile
property, from field survey data obtained throughout the year, it is necessary
to identify predictive relationships between water repellency and commonly
measured soil properties. This paper evaluates these relationships for diverse
soil assemblages.
These soil assemblages include a set of reference soils from the south-west of
Western Australia (an area of 250 000 km2), more
intensively sampled suites of soils in several smaller soil{landscape
associations within the south-west of Western Australia (≅1000
km2), soils from single farms (1-10
km2) and transects (≅0·001
km2), and single soil profiles
(≅m2). The severity of water repellency was
assessed by measuring water drop penetration time in seconds (WDPT) and was
related to intrinsic properties of soils using log-transformed data. For the
set of soils from the West Midland Sandplain the type of land use was also
considered as a variable.
There is a general tendency for WDPT to increase as organic matter content
increases and decrease as the content of fine mineral material increases
(clay, silt, very fine sand). However, there is no single soil property that
is able to predict WDPT adequately. Furthermore, reliability of prediction
decreases as the area of sampling increases. There appear to be no systematic
differences in the capacity of organic matter from pasture or crop to induce
water repellency, but increments of organic matter under bush increase water
repellency at a greater rate than does organic matter from crop or pasture.
New species and isolates of spore-cyst fungi (Plectomycetes: Ascosphaerales) from Australia
Authors: Anderson Denis L. , Gibson Nicole L.
Published: August 2004

Fungi in the genus Ascosphaera (Plectomycetes:
Ascosphaerales) are of agricultural and horticultural interest as they are
only found, in nature, in association with social and solitary bees. To date,
only one member of the genus, A. osmophila, has been
described from Australia. In this paper, four new species of
Ascosphaera, A. duoformis,
A. flava, A. solina and
A. subcuticulata, are described from Australia, together
with previously unrecorded Australian isolates of
A. acerosa, A. atra and the honey
bee chalkbrood fungus, A. apis.
The 1993 strychnine baiting program for mouse control in South Australian grain crops. I. Efficacy
Authors: Mutze G. J.
Published: August 2004

The grain-growing areas of South Australia were affected by a severe mouse
plague during the winter and spring of 1993. Damage to recently sown and
maturing crops was minimised by broadcasting 0.3% strychnine-treated
wheat across affected crops, at a rate of 1 kg ha-1.
Three indices were used to measure relative mouse abundance before and after
treatment: counts of active mouse holes, bait card consumption, and
live-trapping. Hole counts and live-trapping both underestimated treatment
effects. Bait card consumption provided the most accurate indication of
treatment effects. In crops treated across their entire area, treatment
reduced bait card consumption by 87%, with 95% reduction in 18
of 28 crops monitored. In most cases, baiting stopped damage by mice and
allowed farmers to establish healthy crops where previously mice had removed
all the seed sown, and resown, prior to treatment. Perimeter baiting was less
successful owing to rapid reinvasion of treated areas, and reduced average
bait card consumption by only 16%. Strychnine baiting in crop stubbles
was ineffective where weed seeds were abundant.
Iophenoxic acid as a biomarker for rabbits (Oryctolagus cuniculus)
Authors: King D. R. , Robinson M. H. , Eason C. T. , Batcheler D.
Published: August 2004

In recent years, research has shown that iophenoxic acid is useful as a
biomarker in mammals. Its potential was initially demonstrated in several
species of carnivores but it has since been found to be suitable for use in
two species of herbivore, goats (Capra hircus) and deer
(Odocoileus virginianus). We investigated its
suitability for use in European rabbits
(Oryctolagus cuniculus) dosed at levels of 1.5, 5 and 10
mg kg-1. Mean plasma-iodine concentrations in these
groups increased to 328, 989 and 1438 g per 100 mL,
respectively, after three days. The half-life of IPA was greater than 25 days
at all three doses and plasma iodine remained at 4–10 times baseline
levels for 13, 15 and 17 weeks, respectively.
The short-term effect of radio-packages on a free-ranging large herbivore, the northern hairy-nosed wombat
Authors: Woolnough Andrew P. , Johnson Christopher N. , Horsup Alan B.
Published: August 2004

The short-term effect of radio-packages on the activity of the northern
hairy-nosed wombat, Lasiorhinus krefftii, was
investigated using activity data-loggers. Adjustment to the radio-package
occurred between 10 and 18 days following capture and fitting of the
radio-package. Following the adjustment period, activity levels were some
84–97% less than that of the initial activity level after the
attachment of the radio-package. We believe that the adjustment period needs
to be considered in studies involving the attachment of radio- packages.
Mercury and lead during breast-feeding
Authors: Dorea José G.
Published: July 2004

Hg and Pb are of public health concern due to their toxic effects on vulnerable fetuses, persistence in pregnant and breast-feeding mothers, and widespread occurrence in the environment. To diminish maternal and infant exposure to Hg and Pb, it is necessary to establish guidelines based on an understanding of the environmental occurrence of these metals and the manner in which they reach the developing human organism. In the present review, environmental exposure, acquisition and storage of these metals via maternal–infant interaction are systematically presented. Though Hg and Pb are dispersed throughout the environment, the risk of exposure to infants is primarily influenced by maternal dietary habits, metal speciation and interaction with nutritional status. Hg and Pb possess similar adverse effects on the central nervous system, but they have environmental and metabolic differences that modulate their toxicity and neurobehavioural outcome in infant exposure during fetal development. Hg is mainly found in protein matrices of animal flesh (especially fish and shellfish), whereas Pb is mainly found in osseous structures. The potential of maternal acquisition is higher and lasts longer for Pb than for Hg. Pb stored in bone has a longer half-life than monomethyl-mercury acquired from fish. Both metals appear in breast milk as a fraction of the levels found in maternal blood supplied to the fetus during gestation. Habitual diets consumed by lactating mothers pose no health hazard to breast-fed infants. Instead, cows' milk-based formulas pose a greater risk of infant exposure to neurotoxic substances.
Quality of life and self-rated health in relation to changes in fruit and vegetable intake and in plasma vitamins C and E in a randomised trial of behavioural and nutritional education counselling
Authors: Steptoe Andrew , Perkins-Porras Linda , Hilton Sean , Rink Elizabeth , Cappuccio Francesco P.
Published: July 2004

We have carried out a randomised trial comparing brief behavioural counselling with nutritional education counselling to increase fruit and vegetable consumption and associated biomarkers in adults from a low-income neighbourhood. The objective of the present analysis was to assess the impact of interventions on quality of life and health status, and associations between changes in fruit and vegetable consumption, plasma vitamins C and E, and quality of life. Behavioural counselling and nutritional education counselling were carried out in 271 adults in two 15 min sessions in a primary-care setting. Physical and mental health status (medical outcome study short form 36) and self-rated health were assessed at baseline, 8 weeks and 12 months, and analysed on an intention-to-treat basis. Both groups reported increased fruit and vegetable consumption; plasma vitamin E and β-carotene also increased, with significantly greater changes in consumption and plasma β-carotene in the behavioural counselling condition. Physical and mental health status, and the proportion of participants in good self-rated health, increased in both groups to a similar extent. Individual differences in improvements in physical health status and self-rated health were correlated with increases in fruit and vegetable intake and in plasma vitamins C and E, independently of age, gender, ethnicity, financial status, smoking, BMI and use of vitamin supplements. We conclude that participation in the present study was associated with improved health-related quality of life. Increases in fruit and vegetable intake and plasma vitamin levels may stimulate beneficial changes in physical health status in socio-economically deprived adults.
Exogenous dietary xylanase ameliorates viscosity-induced anti-nutritional effects in wheat-based diets for White Pekin ducks (Anas platyrinchos domesticus)
Authors: Adeola Olayiwola , Bedford Michael R.
Published: July 2004

Nutrient utilisation and growth performance responses of White Pekin ducks (Anas platyrinchos domesticus) offered diets containing low- or high-viscosity wheat supplemented with xylanase were investigated in two studies. In Expt 1, six diets consisting of low-viscosity wheat or high-viscosity wheat supplemented with 0·0, 1·5 or 3·0 g xylanase (2590 units/g)/kg diet were used in a true metabolisable energy (TME) bioassay with eight 8-week-old ducks per diet group. In Expt 2, eight pens of ten 3-d-old ducks per pen for each of six wheat-based diets arranged in a 2×3 factorial of low-viscosity or high-viscosity wheat and 0·0, 1·5 or 3·0 g xylanase/kg were used in a 42 d growth study. High-viscosity wheat depressed (P>0·001) TME and xylanase supplementation improved (P>0·001) TME, more so for high-viscosity than low-viscosity wheat. Xylanase supplementation of the high-viscosity wheat-based diet improved (P>0·05) weight gain and gain:feed ratio by 13 and 12% respectively. There was no weight gain or gain:feed ratio response to xylanase supplementation of the low-viscosity wheat-based diet. Xylanase supplementation reduced (P>0·001) the viscosity of duodenal and ileal digesta for high-viscosity but not low-viscosity wheat-based diets. Ileal digestibilities of nutrients and energy were higher (P>0·001) for low-viscosity than high-viscosity wheat-based diets; xylanase supplementation improved (P>0·05) energy, fat, N and starch digestibilities. Given that xylanase supplementation of high-viscosity wheat assuaged its anti-nutritional effect, it is surmised that digesta viscosity plays a role in anti-nutritional effects in wheat-based diets for ducks.