bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of cutting height and cutting interval on rhizome development, herbage production and herbage quality of Lotus pedunculatus cv. Grasslands Maku
Authors: Harris C. A. , Blumenthal M. J. , Kelman W. M. , McDonald L.
Published: August 2004

Summary. A study was conducted to determine the
influence of 3 defoliation intervals (4, 8 and 12 weeks), at 3 harvest heights
(2, 6 and 12 cm) on the rhizome development, herbage production and herbage
quality of Lotus pedunculatus cv. Grasslands Maku.
An interaction between cutting height and cutting interval was measured for
both rhizome number and length. As cutting interval became more frequent,
cutting height was more critical, with cutting to 2 cm every 4 weeks producing
fewer and shorter rhizomes. Rhizome production increased with increased
cutting height and frequent cutting intervals reduced rhizome production. The
impact of severe defoliation was greatest during late autumn and winter, when
peak rhizome expansion occurred. Although lenient cutting treatments
encouraged rhizome development and production it was at the expense of herbage
production, with longer cutting intervals and increasing cutting heights
resulting in less total herbage and lotus production. Increased rhizome
production was also associated with lower in vitro
digestibility, lower nitrogen concentration and higher condensed tannin
concentration of the lotus herbage.
If long rotations are required to maintain a persistent and competitive lotus
sward in temperate and subtropical pasture systems, then
L. pedunculatus cv. Grasslands Maku is unlikely to play
a major role in intensive grazing systems in eastern Australia. This paper
concludes with a discussion of the possible use of strategic grazing practices
of Grasslands Maku swards to achieve a balance between rhizome production and
herbage production.
Processing tomato response to soil compaction and fumigation
Authors: Stirzaker R. J.
Published: August 2004

Summary. Permanent raised beds coupled with reduced
tillage and cover crops are part of the Australian processing tomato
industry’s strategy to move towards more sustainable farming practices.
As a consequence, crops may be planted into denser soils. Previous work showed
that processing tomatoes had considerable tolerance to no-tillage; mild soil
compaction reduced vegetative growth but not fruit yield. This field study
showed that severe compaction not only reduced vegetative growth, but also
extended the duration of the exponential vegetative growth period, so that
fruit and vegetative growth were competing for assimilates. Under these
conditions, fruit yield was severely reduced. Accurate management of drip
irrigation could not compensate for the narrow, non-limiting water range of a
compacted soil. Mild water deficits during the late flowering and early fruit
growth phase also reduced fruit yield. Pot experiments under controlled
conditions revealed an interaction between soil fumigation and tillage
management. Soil fumigation improved shoot growth at high and low soil
densities with the greatest effects observed below ground; root length was
more than doubled when soil cores with a bulk density of 1.79
t/m3 were fumigated. A cover crop of subterranean
clover, grown in the off-season winter period, had no effect on fruit yield
under non-compacted conditions. The implication is that cover crops, which
have been shown to ameliorate adverse soil physical conditions, can only
express their potential when soil conditions in a conventionally managed
system are suboptimal.
Leaf nitrogen as a guide for fertilising macadamia
Authors: Stephenson R. A. , Gallagher E. C. , Doogan V. J.
Published: August 2004

Summary. Despite the lack of evidence for a critical
level of leaf nitrogen in macadamia, fertiliser management has been largely
based on tentative standards for high yielding trees. Trees on a lower plane
of nitrogen nutrition, however, produced higher yields of good quality nuts.
This study was therefore carried out to establish the relationship between
yield and nitrogen status of trees. Three rates of nitrogen fertiliser (0.5,
1.5 and 2.5 kg urea/tree . year; 230, 690 and 1150 g nitrogen
respectively) were applied to macadamia trees in 1 of 5 application
strategies: 1 application in April (floral initiation); 2 applications, one in
April and one in June (inflorescence development); 3 applications, April, June
and November (rapid nut growth and premature nut drop); 4 applications, April,
June, November and January (oil accumulation); and 12 monthly split
applications. Multiple applications were all equal in size. The association
between high yields and low nitrogen status was confirmed. In some, but not
all, years, yield was negatively correlated with leaf nitrogen, accounting for
47 and 59% of the variation in yield of commercially acceptable nuts
(>19 mm diameter) in 1991 and 1993, respectively. It is therefore
recommended that the standard for leaf nitrogen in macadamia be lowered from
1.4–1.5 to 1.3% under Australian conditions. These results raise
concerns at the current trend for leaf nitrogen to be as high as 1.8%.
It would be prudent to cease nitrogen applications on at least a small
experimental block until leaf nitrogen declined to 1.3% and then
maintain this level for at least 3 years and monitor yields.
Lupinosis and reproduction reduce the wool growth of Merino ewes
Authors: Barnes A. L. , Croker K. P. , Allen J. G. , Costa N. D.
Published: August 2004

Summary. Lupinosis was induced in Merino ewes by
subcutaneous injections of phomopsins. Liver damage and impairment of liver
function was measured by increases in plasma activities of glutamate
dehydrogenase and gamma glutamyl transferase, plasma concentrations of
bilirubin, and plasma clearance of bromosulfthalein. The wool growth of the
ewes during and after exposure to phomopsins at different periods relative to
mating was measured, and the impact of lupinosis on annual wool production
assessed. Phomopsin administration decreased the length of staple grown
during, and for at least 6 weeks after, exposure to phomopsins. Mean fibre
diameter of wool grown during this time was also reduced. Annual wool
production of the ewes was affected by exposure to phomopsins, with effects
noted on fleece weight, yield, fibre diameter, strength and position of break.
These effects were minor and varied between experiments. The adverse effects
of reproduction on annual wool production were more significant than those of
phomopsins.
Washing and filtration of wheat straw treated with sodium hydroxide alone or with hydrogen peroxide to modify cell wall composition and in vitro digestibility
Authors: Chaudhry A. S.
Published: August 2004

Summary. This study compared the effect of different
levels (24–160 g/kg DM) of NaOH alone or in combination with 2
levels (130 or 260 g/kg straw DM) of
H2O2 (alkaline hydrogen peroxide,
AHP) in improving in vitro dry matter digestibility of
wheat straw. The study also examined the role of filtration or a water wash of
straws treated at a regulated pH (± s.d.) of 11.5 ± 0.2 to
maximise the effects of NaOH and AHP on in vitro dry
matter digestibility. The experiment was a 3 × 2 × 3 factorial
design, replicated twice, and included 3 straw groups (pH-control,
NaOH-control, AHP), each treated with 2 volumes of chemical solutions (high,
26 L/kg DM containing 48 or 160 g NaOH alone or 160 g NaOH plus 260 g
H2O2 ; low, 13 L/kg DM
containing 24 or 80 g NaOH alone or 80 g NaOH plus 130 g
H2O2 ) and each was subdivided
into 3 groups for storage (unfiltered, filtered, washed). Both NaOH-control
and AHP reduced (P<0.001) neutral detergent fibre
content and increased (P<0.001)
in vitro dry matter digestibility of straw compared with
pH-control. However, AHP was more effective (P<0.001)
in reducing neutral detergent fibre and increasing
in vitro dry matter digestibility of straw compared with
NaOH alone. Filtration and washing of treated straws increased
(P<0.001) neutral detergent fibre and reduced
(P<0.001) in vitro dry matter
digestibility compared with unfiltered samples of treated straws. High volumes
of chemicals were more effective (P<0.001) in
reducing neutral detergent fibre content and improving
in vitro dry matter digestibility of straws compared
with those treated with low volumes of chemicals. While regulation of pH
around 11.5 was effective in reducing neutral detergent fibre and enhancing
in vitro dry matter digestibility the use of filtration
or a water wash of straws following chemical treatments is not recommended.
Response of spring-planted lettuce (Lactuca sativa L.) to freshly-applied and residual phosphorus and to phosphate fertiliser placement on a Karrakatta sand
Authors: Robertson W. J. , McPharlin I. R.
Published: August 2004

Summary. The phosphorus (P) requirements of crisphead
lettuce (Lactuca sativa L. cv. Salinas) were measured
over 2 consecutive spring plantings using superphosphate that was freshly
applied and applied 9 months before planting, at 0–600 kg P/ha on a
newly-cleared Karrakatta sand of low natural P fertility. The response of
lettuce to placement of phosphate fertiliser (banded, broadcast) was also
investigated. There was a significant (P<0.001) head
yield response to level of applied P in all experiments. There was no
significant effect of placement on yield even though the concentrations of P
in the wrapper leaves were on average 12% higher in the broadcast
treatment. A Mitscherlich function described the relationship of P uptake by
whole plants and plant shoots to level of applied P. Recovery efficiency of P
fertiliser (fertiliser P uptake by shoots/P applied, both in kg/ha) by
shoots decreased from 0.12 at 50 to 0.05 at 600 kg applied P/ha.
Phosphorus recovery efficiency by whole plants (shoots plus roots) decreased
from 0.13 at 50 to 0.05 at 600 kg P/ha.
The level of freshly-applied P required for 95 and 99% of maximum
relative yield over the 2 years (maximum yield, 89–112 t/ha) was 185
and 286 kg P/ha (Mitscherlich relationship,
R2 = 0.93), respectively,
at <10 µg/g soil test P (newly-cleared sites). The marketable
yield was 82 and 92% of total yield at 185 and 286 kg P/ha
respectively.
Bicarbonate-soluble P extracted from the top 15 cm of soil was determined on
residual P sites over 2 years where P was applied at 0–600 kg/ha.
These soil test levels were related to head yield in a Mitscherlich
relationship (R2 = 0.90).
The critical soil test P values required for 95 and 99% of maximum
relative yield, over the 2 years, were 81 and 121 µg/g respectively.
Phosphorus in the wrapper leaf at early heading required for 95 and 99%
of maximum yield was 0.40 ± 0.02 and 0.42 ± 0.02% (spline
regression, R2 = 0.81),
respectively. Soil and plant testing could be used to assist in reducing
fertiliser costs, improving the efficiency of use of freshly- and
previously-applied fertiliser P by lettuce and reducing P losses to water
systems on the Swan Coastal Plain in Western Australia. Changing placement
from broadcasting to banding will not improve efficiency of phosphate
fertiliser use by lettuce on Karrakatta sands.
Steer gains, pasture yield and pasture composition on native pasture and on native pasture oversown with Indian couch (Bothriochloa pertusa) at three stocking rates
Authors: Jones R. J.
Published: August 2004

Summary. Pasture production and steer liveweight gain
were compared on native pasture
(Bothriochloa decipiens, Heteropogon contortus, Themeda triandra
and Chrysopogon fallax) and on native pasture oversown
with Indian couch or Indian bluegrass
(Bothriochloa pertusa). This grass was not a planned
introduction to the area but is spreading in Central and North Queensland and
its value as a pasture species is questioned by graziers.
There were 3 nominal stocking rates of 0.3, 0.6 and 0.9 steers/ha. Each
paddock was stocked with 3 steers of stratified ages. The experiment was sown
in March 1988 and terminated in June 1993. The experiment, sited 50 km south
of Townsville in eucalypt woodland on a solodic-solodised-solonetz soil, was
sown in March 1988 and terminated in June 1993.
Increases in stocking rate resulted in a linear decline in both pasture yield
(by 3–5 t/unit increase in stocking rate) and steer gains (by more
than 100 kg/unit increase in stocking rate). Differences between pastures
were apparent only at the medium and high stocking rates where, over time,
Indian couch gave higher pasture yields and steer gains. Younger steers gained
far more weight than older steers. Mean gains over 3 years were weaners 125
kg/year, yearlings 93 kg/year and 2-year-old steers 46 kg/year.
Native pasture remained fairly stable botanically at the low stocking rate,
but the tufted perennial grass species declined at both the medium and high
stocking rates. Sowing Indian couch hastened the botanical changes due to
stocking rate, and it became the dominant species at these higher stocking
rates. At the low stocking rate, the contribution of Indian couch declined
from initial values indicating that this is not an invasive species in the
area at a low stocking rate. Contribution of Indian couch to pasture yield was
linearly related to stocking rate.
Nutritional quality of the Indian couch was similar to the other native
perennial grasses though calcium concentration was higher. Increased steer
gains were related to higher yield on Indian couch pastures at the higher
stocking rates rather than to improved quality.
Maximum liveweight gain/ha was achieved at about 0.6 steers/ha.
Stocking at 0.9 steers/ha was not sustainable. Even at the low stocking
rate, steers would need to spend about 2.8 years on the pastures after weaning
to reach 500 kg liveweight.
It was concluded that B. pertusa is a useful pasture
grass in this environment giving steer gains equal to, or higher than, the
gains from the native pasture which it replaced.
Economic analysis of integrated management of wild oats involving fallow, herbicide and crop rotational options
Authors: Jones R. , Medd R.
Published: August 2004

Summary. The primary objective of this study was to
estimate the economic benefits associated with an integrated weed management
approach for wild oats (Avena fatua and
A. ludoviciana) in northern New South Wales involving
chemical and non-chemical controls. The paper presents a framework for
assessing the population dynamics of wild oats and the economics of a range of
control options over 15 years.
Wild oats is a weed primarily of winter crops which, as a consequence of its
persistence and its impact upon yields, leads to significant economic losses
in the grain growing regions of Australia. In this study, a dynamic
programming model is developed to examine the impact of a range of management
strategies for the control of wild oats in wheat. The strategies evaluated
include conventional herbicide control to reduce weed densities, the use of
selective herbicides to reduce seed set of the weed, and summer crop and
winter fallow rotational options which provide a break in the cereal cycle and
allow accelerated control of wild oat populations. The hypothesis for the
study, that strategies which involve measures that directly reduce seed
production and minimise wild oats seed bank populations will yield the
greatest economic benefit, is acceptable based on the findings of the study.
The work also shows that a dynamic programming model provides a means of
determining the optimal combination of strategies over time for various
initial values of the seed bank. The methodology is considered to have general
application as a framework for evaluating the economics of weed control
problems in annual cropping systems.
Effect of density on growth, development, yield and quality of kabocha (Cucurbita maxima)
Authors: Botwright T. , Mendham N. , Chung B.
Published: August 2004

Summary. The effect of plant density on growth,
development, yield and quality of kabocha (buttercup squash)
(Cucurbita maxima) was examined during 1992–93, at
a field site in Cambridge, Tasmania. Plant densities ranged between 0.5 and
4.7 plants/m2. Marketable and total yields were
fitted to a yield–density model. Total yield followed an asymptotic
trend, approaching 33 t/ha at 4.7 plants/m2,
while marketable yield had a parabolic relationship with density. Marketable
yield increased to a maximum of 18 t/ha at 1.1
plants/m2, while declining at higher densities
because of increased numbers of undersized fruit. Yield of vine marked and
callused fruit did not vary with density, but represented a significant
proportion of the total yield at all densities. High plant density reduced
vegetative growth per plant due to competition for limited resources; as shown
by decreased leaf area, number and length of vines, and plant dry weight.
Yield tended to decline at high densities because of fewer female flowers and
increased fruit abortion per plant. Plants at low densities had more
vegetative growth but decreased yields, as increased abortion of fruit
relative to the higher plant densities left only 1–2 large fruit per
plant. Economic returns varied with plant density. At high densities, variable
costs increased (particularly due to high seed cost) while gross income
declined reflecting the relationship between marketable yield and plant
density. The gross margin therefore declined at high densities.
Using the randomisation in specifying the ANOVA model and table for properly and improperly replicated grazing trials
Authors: Brien C. J. , Demétrio C. G. B.
Published: August 2004

Summary. A method for deriving the analysis of variance
for an experiment is presented and applied to grazing trials. A special
feature of grazing trials, specifically utilised by our method, is that they
involve at least 2 randomisations: treatments are randomised to field units
(for example paddocks or plots), and field units are randomised to animals.
Randomisation results in the confounding (‘mixing up’) of terms
and our method includes separate terms in the analysis of variance table for
confounded terms so that all sources of variability in the experiment have
terms for them included in the table and the confounding between the sources
of variability in the experiment is explicitly displayed in the table. This
information is used in determining the valid error terms and we will present
examples that show how to ascertain these for effects of interest and hence
which effects can be tested. In this it fulfils the same role as the
contentious process of identifying the experimental unit.
It will be demonstrated that the inclusion of separate terms for confounded
terms results in improper replication in grazing trials being automatically
signalled, and makes its ramifications clear.
Lablab (Lablab purpureus) and lupin (Lupinus angustifolius) seeds as supplements for sheep fed low quality roughage
Authors: Dixon R. M. , Garcia E. S. , Domingo J. A. , Holmes J. H. G.
Published: August 2004

Summary. The seeds of lablab
(Lablab purpureus) and lupin
(Lupinus angustifolius) were investigated as supplements
for young sheep. In experiment 1, rumen-cannulated sheep were offered low
quality roughage ad libitum alone or supplemented with
about 5, 10 or 20 g/kg liveweight whole lupin or lablab seed. Rumen
ammonia concentrations were increased by each level of both supplements, and
the increases were greater with lupins than with lablab. The pH of rumen fluid
was decreased by both supplements, particularly when the higher levels were
fed. Dry matter of broken seeds of both legume species rapidly disappeared
from synthetic fibre bags incubated in the rumen. Roughage dry matter
disappearance from synthetic fibre bags decreased
(P<0.05) when 20 g/kg liveweight lupins was fed,
and this level of both supplements reduced (P<0.05)
roughage intake. Total dry matter intake was increased more by lablab than by
lupins, but dry matter and organic matter digestibility tended to be increased
to a lesser extent by lablab. Overall, digestible organic matter intake and
liveweight gain were increased to similar extents by both supplements. Wool
growth was lower (P<0.05) with lablab than lupins,
particularly at the highest level of supplementation, suggesting that
availability of some amino acids was lower with lablab supplement. In
experiment 2, rumen-cannulated sheep were fed low quality roughage
ad libitum and supplemented with about 10 g/kg
liveweight of either lupin or lablab seed. Lectins and protease inhibitors
present in the lablab seed disappeared rapidly from synthetic fibre bags
incubated in the rumen. In conclusion the nutritional value of lablab seed as
a supplement for sheep fed low quality roughage was similar to that of lupin
seed for liveweight gain, but was lower for wool growth.
Insecticide residues in wool from sheep jetted by hand and via automatic jetting races
Authors: Levot G. W. , Sales N.
Published: August 2004

Summary. Sheep with 8 months wool were jetted according
to registered label instructions with diazinon or cyromazine using a standard
Harrington automatic jetting race, a modified jetting race or by hand. The
modified jetting race delivered more insecticide solution than the standard
machine or hand jetting. Sequential insecticide residue analysis of the wool
that had been directly treated was used to calculate the half-lives of
diazinon and cyromazine when applied by the 3 techniques. The half-life of
diazinon applied by hand jetting was about 27 days. The half-life of
hand-jetted cyromazine was about 75 days on sheep. Insecticide half life was
much lower on sheep treated via the standard Harrington automatic jetting
race. This is believed to be because, unlike hand jetting which gives good
liquid penetration of the fleece, much of the applied chemical remains on the
outside of the fleece where it is subject to greater environmental breakdown.
Diazinon residues measured in bale core samples were significantly higher in
wool from hand-jetted sheep compared with sheep treated via the modified
automatic jetting race which in turn were significantly higher than those from
sheep treated via the standard Harrington automatic jetting race. Cyromazine
residues measured in bale core samples were not significantly different for
sheep that had been hand-jetted or jetted via the modified automatic jetting
race. However, residues found in bale samples of wool taken from sheep treated
via the standard Harrington automatic jetting race were significantly lower.
This is thought to be due to the efficiency of application and the slower
degradation of cyromazine in wool.
Residual effects of surface applications of organic matter and calcium salts on the subsoil of a red-brown earth
Authors: Vance W. H. , Tisdall J. M. , McKenzie B.M
Published: August 2004

Summary. The effects of surface soil applications of
organic matter and calcium salts on the subsoil (200–280 mm) of a
red-brown earth (Natrixeralf) were investigated in a field experiment. The
calcium treatments included gypsum, lime or nil-calcium added to the surface
soil. To these calcium treatments, organic matter or nil-organic matter was
added. Three years after final applications of organic matter and calcium
salts to the surface soil, the physical and chemical properties of the subsoil
were measured.
The bulk physical measurements of the subsoil (penetrometer resistance, bulk
density, macroporosity and plastic limit) were not significantly influenced by
the treatments. The electrical conductivity of the subsoil was greater in the
gypsum-treated soil than in the lime- or nil-calcium-treated soils. Subsoil pH
values were lower in the gypsum-treated soil than in the lime- or the
nil-calcium-treated soil.
Dispersion (spontaneous and mechanical) of the clay subsoil decreased with
gypsum-treated surface soil. In treatments where both organic matter and
gypsum were added to the surface soil, the subsoil showed an increased
concentration of exchangeable calcium and decreased spontaneous dispersion of
the clay.
Relationship between root lesion nematodes (Pratylenchus neglectus and P. thornei) and performance of wheat varieties
Authors: Vanstone V. A. , Rathjen A. J. , Ware A. H. , Wheeler R. D.
Published: August 2004

Summary. The root lesion nematodes
Pratylenchus neglectus
andP. thornei occur throughout the cereal cropping areas
of South Australia. In 1996, field trials on the Eyre Peninsula of South
Australia were assessed to determine the relationship between density of
nematodes within field plots in early October and harvested grain yield of 9
wheat varieties. The Pratylenchus species present was
either P. neglectus (at Streaky Bay, Minnipa and
Kalanbi) or P. thornei (at Nunjikompita).
Absence of other major yield limiting factors at these sites in 1996 enabled
determination of the relationship between nematode population and wheat yield.
There was a significant, negative correlation between mean yield and nematode
populations for the 9 varieties at 3 of the sites
(P<0.01 for Streaky Bay and Nunjikompita;
P<0.05 for Minnipa). Root lesion nematodes were
responsible for 56–74% of the observed varietal differences in
yield at these sites. The tolerant variety Excalibur yielded 19%
(Streaky Bay), 23% (Minnipa) or 33% (Nunjikompita) more than the
intolerant variety Spear, and Excalibur resulted in 69, 63 or 66% fewer
nematodes, respectively, than in plots of Spear. Although nematode populations
could not be assessed at the Kalanbi site, varietal yield relations were
similar to the other sites, with Excalibur yielding 18% more than
Spear.
The 9 varieties were ranked for both resistance and tolerance to the 2
nematode species.
Effect of fungicides applied as foliar sprays and trunk injections on nut rot of chestnuts caused by Phomopsis castanea in Victoria
Authors: Washington W. S. , Hood V. , Goubran F. , Hepworth G. , Stewart-Wade S.
Published: August 2004

Summary. Fungicides applied
in vitro, as foliar sprays and trunk injections were
evaluated for the control of phomopsis nut rot, an important storage disease
of chestnuts in Australia caused by Phomopsis castanea.
Benomyl, imazalil, prochloraz and propiconazole were most effective in vitro
against mycelial growth, with EC50 values <0.1
µg/mL. Iprodione was less effective with an
EC50 value between 1 and 10 µg/mL, while
chlorothalonil and phosphorous acid were ineffective with
EC50 values >100 µg/mL. Up to 4 foliar
sprays of benomyl, or phosphorous acid, applied to trees during the growing
season reduced (P<0.05) the incidence of rotted nuts
during cold storage in 2 out of 5 trials, or 1 out of 3 trials respectively.
In one trial, nut rot was reduced from 42.6% in unsprayed trees to 23
or 23.6% in nuts from trees sprayed with benomyl or phosphorous acid
respectively. Prochloraz sprays were not effective. At harvest kernel nut
tissue from trees sprayed with benomyl, prochloraz or phosphorous acid showed
residues of <0.03, 0.14 or from 16 to 145 µg/g respectively.
Trunk injection with imazalil or phosphorous acid at flowering in December did
not control the disease, although in 1 trial, phosphorous acid reduced rot
levels in stored nuts from 51.1% in untreated trees to 41.8%
(P = 0.088). Imazalil treatments caused leaf
scorching and in some cases limb death above the point of injection.
Occasional slight leaf scorching was associated with some phosphorous acid
injections. Residue studies showed that phosphorous acid moved into nut
tissue, but showed little lateral redistribution around the tree.
Soil microbial biomass—what do the numbers really mean?
Authors: Dalal R. C.
Published: August 2004

Summary. Soil microbial biomass comprises less than
5% of organic matter in soil. However, it performs at least 3 critical
functions in soil and the environment. It is a labile source of carbon,
nitrogen, phosphorus, and sulfur; it is an immediate sink of carbon, nitrogen,
phosphorus and sulfur; and it is an agent of nutrient transformation and
pesticide degradation. In addition, microorganisms form symbiotic associations
with roots, act as biological agents against plant pathogens, contribute
towards soil aggregation, and participate in soil formation.
Critical evaluation of the significance of soil microbial biomass is hampered
by the reliable measurement of microbial biomass, and simultaneous
partitioning of its 3 major functions in soil. For comparative purposes, soil
microbial biomass and its derived indices have been successfully used to
measure early changes induced by land use practices, zero tillage, crop
rotations and other cultural practices, nutrient cycling, land disposal of
sewage sludge, and applications of herbicides and insecticides. However, as a
routine analytical tool, it is limited by the cumbersome and time consuming
measurements, lack of benchmarking values and interpretation, ambiguous
relationship with productivity, and cost-effectiveness.
With increasing demand to monitor soil quality and protection of the
environment, improved and rapid techniques, including molecular biotechniques,
will be required to measure soil microbial biomass for its size of sink,
source and rates of turnover. Eventually, agricultural science will benefit
and utilise soil microbial biomass as an analytical tool to produce abundant,
economical, and clean food and fibre.
Can mid infrared diffuse reflectance analysis replace soil extractions?
Authors: Janik L. J. , Merry R. H. , Skjemstad J. O.
Published: August 2004

Summary. Recent developments in infrared spectroscopy
and computer software, together with decreasing spectrometer costs, have
resulted in an increase in the potential for soil analysis. Infrared
spectroscopy in both the near and mid infrared ranges allows rapid acquisition
of soil information at quantitative and qualitative, or indicator, levels for
use in agriculture and environmental monitoring. In this paper, we describe
how mid infrared diffuse reflectance analysis can provide results comparable
in accuracy with many traditional extractive and digestion laboratory methods
in soil studies, with the possibility of either replacing or enhancing them.
Examples are given for estimation of lime requirement, organic carbon,
exchangeable cations, air-dry moisture, clay content and biological
indicators. Infrared methodology appears to have advantages in facilitating
some soil analyses that are otherwise very time-consuming or expensive, or
where spatially dense data is required.
Precision agriculture — opportunities, benefits and pitfalls of site-specific crop management in Australia
Authors: Cook S. E. , Bramley R. G. V.
Published: August 2004

Summary. Precision agriculture is the term given to crop
management methods which recognise and manage within-paddock spatial and
temporal variations in the soil–plant–atmosphere system. This
paper reviews the principles, practice and perceived benefits of precision
agriculture.
The objective of precision agriculture is to improve the control of input
variables such as fertiliser, seed, chemicals or water with respect to the
desired outcomes of increased profitability, reduced environmental risk or
better product quality. The practice can be viewed as comprising 4 stages:
information acquisition; interpretation; evaluation; and control. Much of the
technology to acquire information and control machinery is available or at a
late stage of development. However, methods of interpretation are less well
developed.
Soil chemical analytical accuracy and costs: implications from precision agriculture
Authors: Rossel R. A. Viscarra , McBratney A. B.
Published: August 2004

Summary. This article reviews soil sampling and soil
chemical analysis, discussing their implications from, and applications in,
precision agriculture. The variability of a number of agriculturally important
soil chemical properties was investigated and the ‘nugget’
variance or effect discussed in terms of its importance in determining the
proportion of not only short-range spatial variation, but also sampling and
measurement error. Comments were then made on the accuracy of laboratory
methods. Analytical variances were compared with world-average and estimated
nugget variances for a field in New South Wales, the comparison showing that
analytical precision needs to be maintained or improved when developing or
adapting analytical methods for precision agriculture. A simple cost-analysis
showed that soil chemical analytical costs are much too large for economic use
in precision agriculture, costs in Australia being higher than in the United
States. The conclusion this paper draws is that, for large-scale
implementation of precision agriculture, the development of field-deployed,
‘on-the-go’ proximal soil sensing systems and scanners is
tremendously important. These sensing systems or scanners should aim to
overcome current problems of high cost, labour, time and to some extent,
imprecision of soil sampling and analysis to more efficiently and accurately
represent the spatial variability of the measured properties.
Improving management of rice in semi-arid eastern Indonesia: responses to irrigation, plant type and nitrogen
Authors: Borrell A. K. , Kelly R. M. , Cooten D. E. Van
Published: August 2004

Summary. A number of field experiments were undertaken
in eastern Indonesia with the aim of improving rice production in this
semi-arid region. The objectives of these studies were to examine the effects
of irrigation method (raised beds under saturated soil culture
v. flooded system), irrigation frequency (daily
v. twice weekly) and genotype (traditional
v. improved) on rice yield and components of yield, and
to examine the response of rice growth on raised beds to sowing time and
nitrogen fertilisation.
Recent studies in northern Australia have demonstrated that rice can
successfully be grown under saturated soil culture. In the Australian studies,
grain yield and quality were maintained, yet saturated soil culture used
32% less water than the flooded control in both wet and dry seasons.
Higher efficiencies of water use for rice production with saturated soil
culture in semi-arid tropical Australia suggest that similar benefits may be
realised with this method of irrigation in West Timor.
The experiments in West Timor were undertaken within a low-external-input
system, and all experiments were affected by drought. The central issue is one
of aligning crop growth with water availability to ensure adequate quantity
and quality of grain production at the end of the season. On this basis, a
number of practical strategies for improving rice production under
water-limited conditions in West Timor are suggested. First, time of sowing in
the wet season is important, with early-sown crops escaping end-of-season
drought. Significantly, the improved genotype (cv. Lemont) was only able to
fill its grain adequately if sown early in the wet season, thereby avoiding
drought during grain filling.
Second, providing soils are sufficiently deep, rice can successfully be grown
under saturated soil culture in West Timor. Importantly, preparation of raised
beds before the wet season enables rice crops to be sown early, maximising the
use of rainfall for crop production. Twice weekly irrigation of rice on beds
was found to be more efficient than irrigating daily or flooding the bays.
Third, no differences in grain yield were found between the improved
short-statured genotype (cv. Lemont) and the taller traditional genotype under
the low-external-input system, although differences in components of yield
were observed in the wet and dry seasons. There is some evidence that the
traditional genotype filled grain better when water was limiting during grain
growth by restricting vegetative production and enabling the crop to finish.
Seed production of Lotus uliginosus cv. Sharnae in response to plant population density
Authors: Arango N. , Jacobs B. C. , Blumenthal M. J.
Published: August 2004

Summary. An experiment was carried out under irrigation
in the field to determine the influence of plant population density (7.5, 15,
30 and 60 plants/m2) on growth, development and
yield of the pasture legume Lotus uliginosuscv. Sharnae.
Reproductive development (flowering, pod set and stages of pod development)
was recorded from 79 days after establishment and harvests were taken on 3
occasions during pod development: 118, 138 and 158 days after establishment.
At each harvest, plants were divided into leaf, stem and pods. The pods were
further separated into maturity classes on the basis of colour, and seed
number and weight measured for each class.
Harvesting late (i.e. 158 days after establishment) maximised seed yield (113
g/m2) and seed quality (27% immature, green
pods). Seed yield per unit area up to 158 days after establishment was
relatively insensitive to plant population up to 60
plants/m2 because the response of individual plants
of lotus was highly plastic. At 158 days after establishment, dry matter per
plant declined from 985 g at 7.5 plants/m2 to 713 g
at 60 plants/m2. At the same time, seed number per
plant and seed weight per plant were reduced from 27 400 to 3230 seeds and
from 15.5 to 1.65 g, respectively, across the range of population densities.
Despite the lack of a clear optimum plant population for maximum seed yield,
some aspects of seed quality declined at high population density. For example,
single seed weight fell by about 10% from 0.563 mg and the proportion
of the harvest contributed by seeds from immature pods rose from 18 to
33%, as population density increased from 7.5 and 60
plants/m2.
Seed quality and ease of management, rather than yield, may be the most
important considerations when seed growers choose a sowing rate for a
L. pedunculatus cv. Sharnae seed crop.
Protection from restrike provided by flystrike dressings
Authors: Levot G. W. , Sales N.
Published: August 2004

Summary. An organophosphate-resistant strain of the
Australian sheep blowfly, Lucilia cuprina, was used to
initiate 4 artificial flystrikes onto each of 156 Merino sheep that carried 6
cm of wool growth. Strikes were allowed to develop for 2 days by which time
large third instar larvae were present. At that time the strikes were shorn
and 1 of 11 registered flystrike dressings was applied according to label
directions. On 13 sheep, strikes were shorn but otherwise left untreated
(controls). When inspected 1 day later only 4 out of 52 control (shorn only),
and 1 out of 572 insecticide-treated strikes still contained larvae. One week
after treatment and following exposure to 15 mm of artificial rainfall, the
sheep were subjected to severe blowfly pressure in a fly-proof animal house.
Egg masses were laid onto 25 healing wounds on 12 of the 13 control sheep.
Restrikes developed from 17 of the 25 egg masses. Only sheep in 3 treatment
groups had no eggs laid on the dressed lesions, however, compared with the
controls, significantly fewer egg masses were laid on lesions on all but 1
treatment group. Although egg masses were found on 73 insecticide-treated
lesions on 40 sheep, restrikes were recorded on only 2 lesions. Although most
flystrike dressings have poor larvicidal efficacy, over 90% of strikes
resolved by shearing alone. All of the registered products provided adequate
protection from restrike either by repelling blowflies or by killing their
eggs or the larvae that hatched from them before strikes established.
Susceptibility of apple cultivars to apple scab and powdery mildew in Victoria, Australia
Authors: Washington W. S. , Villalta O. N. , Ingram J. , Bardon D.
Published: August 2004

Summary. Twenty apple cultivars were assessed over 3
seasons for their susceptibility to natural infection with scab (caused by
Venturia inaequalis) and powdery mildew (caused by
Podosphaera leucotricha). It was evident that a number
of important commercial cultivars are highly susceptible to leaf scab (average
incidence of leaf scab: Pink Lady, 40.2% of leaves; Lady William,
37.1%; Braeburn, 20.0%; and New Jonagold, 18.7%) and
powdery mildew (average incidence of leaf mildew: New Jonagold, 23.0%;
Pink Lady, 17.8%). There was a high level of resistance to leaf scab in
the cultivars Florina-Quérina, Redfree and Jonafree (all less than
1% incidence on leaves) and to powdery mildew in the cultivar Earlidel
(no infection observed). The cultivars Jonathan, Bonza and Red Elstar showed a
useful level of resistance to scab (average incidence of leaf scab between 1.6
and 3.2%), while the cultivars Red Fuji, HiEarly and Redfree all showed
some resistance to powdery mildew (average incidence of mildew between 2.6 and
5.9%). Observations made on the low and variable numbers of fruit
produced by some trees in their third year after planting showed that Pink
Lady and Lady William were highly susceptible to fruit scab (67.6 or
57.6% scabbed fruit respectively). Twig infection by scab was also
observed on shoots of the current season’s growth of Pink Lady.
Effect of growth promotant implants on liveweight change, wool and carcass characteristics of mature wethers grazing dry season pastures
Authors: Bortolussi G. , Bird A. R.
Published: August 2004

Summary. Thirty-two mature recently shorn wethers (mean
liveweight 52.1 kg) were implanted with 1 of 4 different hormonal growth
promotants (Ralgro, Compudose, Revalor-S and Synovex-H) to determine animal
production responses on dry season pastures. The wethers were grazed for a
period of 135 days on dry season native Mitchell grass
(Astrebla spp.) pastures infested with
Acacia nilotica. The wethers were weighed monthly. Four
months after commencement of the experiment, the wethers were shorn to
determine wool characteristics (micron, yield and staple length). At 2 weeks
post-shearing the wethers were slaughtered to determine carcass attributes.
Serial rumen ammonia concentrations indicated that diet quality was declining
throughout the experiment. Relative to the controls, the Compudose implant had
increased (P<0.05) average daily gain by day 29 of
the experiment. At days 93 and 118 post-implantation, compared with the
control wethers, Compudose and Synovex-H implantation of wethers had
significantly (P<0.05) increased liveweight and
average daily gain. Average daily gain of the control, Compudose and Synovex-H
wethers to day 93 and 118 was 3, 32 and 33, and 12, 43 and 43 g/day
respectively. There was no effect of Ralgro or Revalor-S on liveweight or
average daily gain. There was no significant effect of hormonal growth
promotant treatment on hot carcass weight, fat depth or fleece
characteristics.
We conclude that under declining nutritional conditions, hormonal growth
promotant treatment of mature wethers with either Compudose or Synovex-H
improves liveweight performance on dry season Astrebla
spp. pastures. The small improvement in liveweight may not provide economic
returns for sheep destined for Asian export or manufacturing meat markets. An
implant dose of 8 mg of oestradiol (Compudose) or a combined dose of 75 mg of
testosterone and 7.5 mg of oestradiol (Synovex-H), was adequate to stimulate
liveweight gain under these conditions. The effects of implantation on carcass
and fleece attributes require further investigation.
The impact of commodity prices and seasonal conditions on the adoption of productive pasture technology during the final 18 months of the Grassland’s Productivity Program
Authors: Trompf J. P. , Sale P. W. G.
Published: August 2004

Summary. Nineteen participants in the Grassland’s
Productivity Program were surveyed in autumn 1997 to determine whether they
had continued to adopt productive pasture practices during the final 18 months
of the program. The objective was to determine whether changes in commodity
prices in 1996, involving falls in wool and beef prices and increases in prime
lamb prices, and unfavourable seasonal conditions, impacted on the continuing
adoption of productive pastures by participants of the Grassland’s
Productivity Program.
Despite the less favourable market and seasonal conditions, the
Grassland’s Productivity Program participants continued to increase
their adoption of productive pastures, almost trebling the area of land under
the productive pasture technology from mid 1995 to 1997. This was achieved by
rationalising farm expenditure in ways to cope with the less favourable
conditions. The first was to undertake more pasture manipulation instead of
high-cost pasture renovation. The second was to maintain expenditure on
phosphorus fertiliser but focusing the application on more productive pasture
paddocks. As a result the stocking rate across the whole farm was only
increased marginally (by 0.2 dse/ha) from 1995 to 1997. Nevertheless the
participants predicted that they would increase their stocking rate by an
average of 17% across their farms, from 10.9 to 12.7 dse/ha, by the
year 2000.
The continuing strong commitment to adopt productive pastures is highlighted
by the future intention of over half of the Grassland’s Productivity
Program participants (53%) to implement the technology over their whole
farm. The remaining participants intended to have at least half their farm
under productive pastures. There was no discernible difference between wool
growers and prime lamb producers in achieving adoption intentions apart from
the area of the farm that is sown to productive species. This indicates that a
short-term change in enterprise profitability is not necessarily a major
determinant of adoption of more intensive grazing practices by participants in
this type of group-facilitated program.
Review of the Australian Nicoletiinae (Zygentoma : Nicoletiidae)
Authors: Smith G. B.
Published: August 2004

The Australasian species and records of Nicoletiinae are reviewed and thephylogeny discussed. The genera Trinemura Silvestri,Metrinura Mendes and HemitrinemuraMendes are redefined on the basis of the number of vesicles and stylets on theurosternites, and a new genus Subtrinemura is described.The keys of Mendes and Wygodzinsky are combined and modified to form a key tothe world genera of Nicoletiinae. Trinemura watsoni, sp.nov., T. troglophila, sp. nov.,T. calcaripalpa, sp. nov.,Metrinura humusa, sp. nov.,M. queenslandica, sp. nov.,M. pedicella, sp. nov. andSubtrinemura spelaea, sp. nov. aredescribed.M. russendenensis (Smith & Shipp), comb.nov. is redescribed. The identity of T. novaehollandiaeSilvestri, M. novaecaledoniae (Silvestri),S. excelsa (Silvestri), comb. nov.,S. anemone(Smith), comb. nov.,S. norfolkensis (Smith), comb. nov.,H. pacifica (Carpenter), comb.nov.,H. gracilis (Carpenter), comb. nov. andH. subarmata (Paclt) as well as two further undescribedspecies of Trinemura and Metrinuraare discussed and details of measurements and head setation given. A key isprovided to the species of Trinemurodes,Trinemura, Metrinura,Hemitrinemura and Subtrinemura.Measurement data for all Australasian species show that variation withinspecies is often as great as variation between species and it is concludedthat measurements can be used to separate only certain species with quiteunusual proportions. Mature male specimens with their obvious secondary sexualcharacteristics are necessary for the definitive determination of all species.
Obscuromyia, a remarkable new genus of the endemic Australian tribe Myiotrixini (Diptera : Tachinidae : Tachininae)
Authors: Barraclough David , O'Hara James
Published: August 2004

The endemic Australian tribe Myiotrixini is reviewed and a new genus andspecies described. The monotypic genus Myiotrixa Brauer & Bergenstamm, 1893, is known from all States except the NorthernTerritory, but has been most frequently collected from south-easternAustralia; the single species, M. prosopina, is aparasite of the native Australian cockroachPlatyzosteria castanea Brunner.Obscuromyia, a new monotypic genus of Myiotrixini fromnorthern Western Australia, is described and the relationship between it andMyiotrixa discussed. Striking synapomorphies of the maleand female terminalia corroborate the sister-group relationship betweenObscuromyia and Myiotrixa. These synapomorphies are the medially fused pregonites which encircle the base ofthe aedeagal apodeme in the male, and in the female the lack of sclerotisedsternites in most of the abdomen and ovipositor, and the non-extensible andnon-piercing ovipositor in which segment 8 forms a sclerotised cylinderincised dorsally and ventrally. A revised diagnosis of the Myiotrixini isprovided along with a diagnostic key to the two genera.