bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of once- and twice-yearly weaning of an extensive herd in northern Australia
Authors: Sullivan R. M. , O'Rourke P. K. , Neale J. A.
Published: August 2004

Summary. Continuous mating is common in northern
Australian beef herds. The resulting calves are born throughout the year
making weaning and herd management difficult. Calves born late in the wet
season do not reach suitable liveweight for weaning until late in the year.
Low liveweight and poor feed conditions make management of these animals for
subsequent turnoff or breeding more difficult.
We recorded the growth and survival of all progeny and reproductive
performance of heifers from 2 groups of 250
Bos indicus-Bos taurus-cross cows
grazing native pastures at Kidman Springs, Northern Territory, for 5 years
from July 1985. Calves were weaned in June only (W1) or June and October (W2).
Unweaned calves remained with their dams until June the following year and
heifers entered the breeding herd as 2 year olds.
Calves weaned in June (WJ) were heaviest (157.1 kg;
P<0.05) but gained least (84.6 kg;
P<0.05) over the following year. Unweaned (UW) calves
were lighter (51.1 kg; P<0.05) at branding time, in
June, than those weaned in October (WO; 66.8 kg). However, they gained more
weight (144.5 v. 112.4 kg;
P<0.05) over the following year than WO calves
because of a superior wet season growth rate, so that WO calves were lightest
(P<0.05) at the yearling muster. Mortality rates of
all calf groups were low (2.5%).
Liveweight at branding and liveweight gain to yearling stage affected whether
heifers subsequently joined the breeding herd. More
(P<0.05) heifers from WJ joined the herd than from WO
and UW groups. Overall, 63.6% of heifers were selected as replacement
breeders (no difference between W1 and W2). Bull control was difficult and
many heifers (48%) conceived before the planned start of mating.
Cumulative conception rate was 91.3% by 30 months post-branding. In the
first year, 60% of heifers mated were confirmed pregnant, but
reproductive losses of 25.6% from pregnancy diagnosis to branding
contributed to a branding rate of 44.9%. The conception rate of heifers
when lactating was 18.6%. Mortality during the first year in the herd
was 11.7%. In general, WJ heifers had lower mortalities, higher
conception, calving and weaning rates, and higher conception rates when
lactating than WO or UW heifers.
Animals weaned in October were identified as the most difficult group to
manage because of lower liveweight as 2 year olds compared with WJ and UW
calves. This affected the numbers of heifers suitable for joining.
Cost-effective management systems are needed to improve growth rates or delay
onset of oestrus in these animals.
Production and management considerations of running wethers, hemi-castrates and induced cryptorchids for wool production
Authors: Foster F. M. , Jackson R. B. , Hopkins D. L. , Corkrey R.
Published: August 2004

Summary. Male, fine wool Merino sheep which had been
subjected to different methods of castration as lambs were assessed from 22 to
46 months of age for their suitability for wool production, their tolerance to
posthitis and their carcass characteristics.
Hemi-castrates produced significantly (P<0.001) more
clean wool than induced cryptorchids of a similar fibre diameter. Induced
cryptorchids and hemi-castrates were significantly
(P<0.05) heavier than wethers. Partial hemi-castrates
and induced cryptorchids had significantly (P<0.001)
heavier and leaner carcasses (lower GR measurement) than wethers and
testosterone-treated wethers. Induced cryptorchidism and hemi-castration
proved to be effective means of reducing the prevalence of posthitis such that
as the degree of castration decreased the proportion of animals with higher
posthitis scores decreased (P<0.001).
Testosterone levels in induced cryptorchids (1.01 ng/mL) and
hemi-castrates with partial reduction of the parenchyma (0.83 ng/mL) were
similar, whereas hemi-castrates with complete reduction of the parenchyma in
the 1 remaining testicle had a significantly
(P<0.001) lower level (0.32 ng/mL) and
significantly (P<0.001) lighter testes.
Development of horns and obvious scrotums by induced cryptorchids and
hemi-castrates with partial reduction of the parenchyma in the 1 remaining
testicle attracted penalty rates at shearing and slaughter. Some induced
cryptorchids and hemi-castrates exhibited masculine behaviour, but they were
unlikely to be fertile because although spermatozoa were present they were
abnormal and/or non-motile.
Hemi-castrates with full reduction of the parenchyma in the 1 remaining
testicle offer significant advantages over the other groups for wool
production. Severe posthitis was not observed, they were infertile, they did
not attract penalty rates for shearing or slaughter and their clean fleece
weight, wool quality, carcass weight and grade were comparable with or
superior to wethers. To reduce dependence on synthetic hormones to control
posthitis, traditional complete castration techniques could be replaced with
this type of partial castration in wool-producing flocks.
Factors affecting the early growth of Leucaena leucocephala
Authors: Brandon N.J , Shelton H.M
Published: August 2004

Summary. Slow establishment has been identified as a
major limitation to the more widespread adoption of the fodder tree
Leucaena leucocephala in Queensland. Field experiments
were conducted at Mt Cotton, Gayndah and Theodore in south-east Queensland
during the 1987–88 summer to identify the major factors limiting first
year yield of leucaena. Treatments at each site included irrigation (applied
at sowing only, or at intervals throughout the trial), and rates of phosphorus
(P), nitrogen (N) and lime. Attack by psyllid insects, weed competition and
defoliation by wildlife were noted and minimised where possible.
Soil moisture appeared to be the major limitation to plant growth at the
inland sites of Theodore and Gayndah where post-establishment irrigation
increased final dry weight by 250%. Waterlogging reduced plant height
increase at the low lying Mt Cotton site following higher than normal
rainfall. Increase in plant height at the other sites stopped when night
temperatures fell below 15°C.
Application of P at 75–1200 kg/ha tripled final dry weight of
leucaena at Mt Cotton (5 mg/kg bicarbonate-extractable P) but had no
effect at Theodore (10 mg P/kg) or Gayndah (35 mg P/kg). Larger than
normal responses to P during early growth may be due to slow colonisation of
the roots by arbuscular mycorrhiza. Application of N (200 kg N/ha)
increased dry weight of Rhizobium-inoculated leucaena by
27% at Theodore but had little or no effect at the other sites.
Application of lime had no significant effects on plant height or dry weight
of leucaena at Mt Cotton despite the soil being slightly acidic (pH 5.9 in 1 :
5 H2 O suspension).
Further work on the role of colonisation by arbuscular mycorrhiza fungi in
determining uptake of P by leucaena is warranted in view of the large response
to very high rates of P in young seedlings at Mt Cotton.
Prepartum supplementation effects on growth and fertility in Bos indicus-cross cows
Authors: Fordyce G. , Fitzpatrick L. A. , Mullins T. J. , Cooper N. J. , Reid D. J. , Entwistle K. W.
Published: August 2004

Summary. Three experiments were conducted in the dry
tropics of north Australia using Bos indicus-cross cows.
Cows in mid–late pregnancy were either unsupplemented during the late
dry season or offered ad libitum (2 kg/day) molasses
with 7.4% urea (w/w) (M8U) or cottonseed meal (1 kg/day) for up
to 54 days commencing 2 months before the start of the calving season.
Supplementation reduced weight loss in experiments 1 and 2
(P<0.05), but had no significant effect on weight or
body condition in experiment 3. Supplementation had no effect on subsequent
calf growth or cow lactation yields.
Following early wet season rains in experiment 1, 9 and 49% of cows
were ovulating 40 and 80 days post-partum, respectively, with no effect of
supplementation. In experiment 2, 10 and 100% of cows had ovulated by
60 and 200 days post-partum, respectively. At any time between 80 and 180 days
post-partum, supplemented cows were more likely to be cycling
(P<0.05), independent of supplementation effects on
weight or body condition. The average post-partum interval to oestrus was 30
days less in cows supplemented for 42 days (P =
0.08).
In experiment 3, pregnancy rates in 1/2 and 3/4 Brahmans supplemented
with M8U for 54 days (MU54) or whose calves were weaned at 2–3 months of
age (WEAN) were 14% higher in the latter 2 months of mating than in
cows supplemented for less than 40 days. Good seasonal conditions resulted in
high pregnancy rates in all mature 5/8 Brahmans; when not weaned early,
their average calving to conception interval (CCI) was 54 days (s.e. =
8.5 days). Pregnancy rates of first-lactation 5/8 Brahmans (average CCI of
125 days) supplemented for 39 days or less and weaned when calves averaged 6
months of age were 14–32% lower between 2 and 9 months
post-partum than in contemporaries in the MU54 or WEAN treatment groups.
It was concluded that dry-season supplementation of mid- to late-pregnant
Bos indicus-cross cows with an energy concentrate for
42–54 days (‘spike’ feeding) may reduce post-partum
anoestrus intervals via a mechanism which is not dependent on the effects on
weight or body condition.
Non-invasive assessment of pineapple and mango fruit quality using near infra-red spectroscopy
Authors: Guthrie J. , Walsh K.
Published: August 2004

Summary. The potential of near infra-red (NIR)
spectroscopy for non-invasive measurement of fruit quality of pineapple
(Ananas comosus var. Smooth Cayenne) and mango
(Magnifera indica var. Kensington) fruit was assessed. A
remote reflectance fibre optic probe, placed in contact with the fruit skin
surface in a light-proof box, was used to deliver monochromatic light to the
fruit, and to collect NIR reflectance spectra (760–2500 nm). The probe
illuminated and collected reflected radiation from an area of about 16
cm2. The NIR spectral attributes were correlated with
pineapple juice Brix and with mango flesh dry matter (DM) measured from fruit
flesh directly underlying the scanned area. The highest correlations for both
fruit were found using the second derivative of the spectra
(d2 log
1/R) and an additive calibration equation. Multiple
linear regression (MLR) on pineapple fruit spectra (n
= 85) gave a calibration equation using
d2 log 1/R at wavelengths of
866, 760, 1232 and 832 nm with a multiple coefficient of determination
(R2) of 0.75, and a standard error
of calibration (SEC) of 1.21 °Brix. Modified partial least squares (MPLS)
regression analysis yielded a calibration equation with
R2 = 0.91, SEC =
0.69, and a standard error of cross validation (SECV) of 1.09
oBrix. For mango, MLR gave a calibration equation using
d2 log 1/R at 904, 872, 1660
and 1516 nm with R2 = 0.90,
and SEC = 0.85% DM and a bias of 0.39. Using MPLS analysis, a
calibration equation with R2
= 0.98, SEC = 0.54 and SECV = 1.19 was obtained. We
conclude that NIR technology offers the potential to assess fruit sweetness in
intact whole pineapple and DM in mango fruit, respectively, to within 1°
Brix and 1% DM, and could be used for the grading of fruit in fruit
packing sheds.
Growth interactions of navy bean varieties with sowing date and season
Authors: Redden R. J. , Tompkins W. , Usher T.
Published: August 2004

Summary. Five navy bean
(Phaseolus vulgaris L.) varieties were sown monthly from
December to February at Kingaroy in 1991–94, plus a November planting in
1993 and 1994, to investigate how varietal differences may be affected by time
of sowing.
For grain yield there were seasonal interactions with both sowing date and
variety, with maximums for a December sowing in 1991 and 1994 but a minimum in
1993 for November and December sowings due to infection with grey mould
(Macrophomina spp.). Yields were least with the February
sowing in 2 years and for mean yield over years. The early maturing varieties,
Actolac and Pan 12, maximised yield with a January sowing, and the late
varieties, Sirius, Rainbird and Spearfelt, with a December sowing.
Time to flowering and maturity was greatest for November plantings, while
minimum time to flowering and maturity was subject to marked interactions with
varieties and season.
Determinate varieties Rainbird, Spearfelt and Actolac were non-viny across
sowing dates, while semi-determinate Sirius and Pan 12 were less viny with
later sowing.
Canopy height, pod height and lodging were affected by interactions amongst
varieties, seasons and sowing dates, with lodging tending to increase with
canopy height and yield gains. Pod height was correlated with canopy height
and was greatest for varieties Sirius and Rainbird. Spearfelt consistently had
low lodging.
December–January sowing is recommended for Sirius, Rainbird and
Spearfelt, and a January sowing is recommended for Actolac and Pan 12.
Diagnostic leaf nutrient standards for low-chill peaches in subtropical Australia
Authors: Huett D. O. , George A. P. , Slack J. M. , Morris S. C.
Published: August 2004

Summary. A leaf nutrient survey was conducted of the
low-chill peach cultivars, Flordaprince (October maturing) and Flordagold (mid
November–early December maturing) at 3 commercial sites in both northern
New South Wales and southern Queensland. Recently mature leaves from the
middle third of a current season’s fruiting lateral (spring flush) were
sampled at stone hardening and 2-weeks postharvest and of a non-fruiting
lateral at maturity of the summer flush (after summer pruning) during the
1992–93 and 1993–94 seasons. At an additional site in New South
Wales (Alstonville), leaf nutrient concentrations were also determined on cv.
Flordagem (early November maturing) at 2-week intervals during both seasons.
Soil (0–30 cm) chemical determinations were conducted at all sites at
2-weeks postharvest
Seasonal trends in leaf nutrient composition were associated with a leaf
age–maturity effect. As flush leaves matured during spring, and as
mature leaves aged after hardening of the summer flush, nitrogen (N)
concentration declined and calcium (Ca) concentration increased. Nitrogen and
Ca concentrations increased when young leaves produced from the summer flush
were sampled. Time of sampling produced the most consistently significant
(P<0.05) main effects on leaf nutrient concentration.
The 2-week postharvest period was selected as a convenient time to
sample—when leaves were of a consistent age and maturity, and the effect
of crop load on tree nutrient reserves was still present.
Paclobutrazol, which reduces vegetative growth in stonefruit, was applied to
all Queensland sites and, as a consequence, mid lateral leaves contained
higher (P<0.05) Ca, magnesium (Mg) and chloride (Cl)
and lower (P<0.05) N and phosphorus (P)
concentrations than leaves from New South Wales sites. State effects can
therefore be interpreted as paclobutrazol effects. Cultivar effects
(P<0.05) occurred for many leaf nutrients, however,
at the 2-week postharvest sampling, concentrations were sufficiently similar
to combine as a narrow adequate concentration range for both cultivars. The
diagnostic adequate leaf nutrient concentrations were within the range
developed for high-chill peaches (Leece et al. 1971)
with the exception of lower Ca, lower Mg for New South Wales (both cultivars),
lower iron for Flordaprince (both states), higher P for Flordaprince in New
South Wales and higher manganese values for Queensland (both cultivars).
Regression analyses were conducted between leaf and fruit nutrient
concentrations and soil chemical properties. The only consistent result
demonstrated that as the soil Ca : Mg ratio increased, leaf Mg concentration
decreased exponentially (P<0.001), indicating that
the practice of heavy annual agricultural limestone or gypsum applications in
the absence of Mg fertiliser, which had been adopted by several growers in the
survey, is associated with lower leaf Mg concentrations.
Effects of applying insecticides to control aphid vectors and cucumber mosaic virus in narrow-leafed lupins Lupinus angustifolius)
Authors: Bwye A. M. , Proudlove W. , Berlandier F. A. , Jones R. A. C.
Published: August 2004

Summary. Narrow-leafed lupins
(Lupinus angustifolius) were sown in 4 field experiments
to investigate the effects of applying organophosphorus and carbamate
insecticides on the spread of cucumber mosaic virus (CMV), which is
transmitted non-persistently by aphids. The seed sown carried 0 or 5%
CMV infection and seed-infected plants were the primary source for subsequent
virus transmission by aphids. Virus incidence was gauged by calculating the
percentage of plants per plot showing typical current-season CMV symptoms. At
final assessment in plots sown with 5% infected seed, recorded CMV
incidence was always significantly smaller (up to 3-fold less) when they
received sprays of pirimicarb and/or methamidophos every 2 weeks than when
they received no insecticide. When single or double strategic sprays of
methamidophos or a mixture of pirimicarb/thiometon were applied in late
August or early September, they either decreased recorded CMV incidence (up to
2-fold less infection) or had no significant effect on it. Recorded CMV
incidence was not significantly diminished by dressing seed with disulfoton or
by single- or double-foliar applications of pirimicarb used alone. However,
pirimicarb sprays applied every 2 weeks improved grain yield (24%
increase), as also did single or double applications of pirimicarb
(14%). In one experiment, applications of methamidophos every 2 weeks
to plots originally sown with 5% infected seed resulted in increased
grain yield (35%) and yields were increased in plots sown with healthy
seed whether sprayed every 2 weeks with methamidophos or left unsprayed
(42–61%).
Pirimicarb suppressed numbers of colonising
Acyrthosiphon kondoi and
Aphis craccivora to a greater extent than those of
Myzus persicae, especially when sprayed every 2 weeks.
Single-, double- and sprays of methamidophos every 2 weeks also decreased
numbers of Acyrthosiphon kondoi, but had less effect on
M. persicae. When different insecticides were tested for
their abilities to kill colonising, insecticide-resistant
M. persicae, methamidophos was the most effective.
This work suggests that single or double strategic foliar sprays of
organophosphorus or carbamate insecticides cannot be relied on to control CMV
adequately to be recommended for use in increasing grain yields in
CMV-infected lupin grain crops.
Responsiveness of barley cultivars to nitrogen fertiliser
Authors: Fathi G. , McDonald G. K. , Lance R. C. M.
Published: August 2004

Summary. Genotypic differences in responses to nitrogen
(N) fertiliser of 6 cultivars of barley (Clipper, Stirling, Weeah, Schooner,
Chebec, Skiff) grown at 8 different rates of N were examined in 2 seasons.
Measurements of vegetative growth, N content, grain yield, grain protein
concentration (GPC) and yield components were taken to identify traits that
may contribute to high yield responsiveness.
The optimum rates of N for dry matter production at ear emergence
(DMee) were greater than 80 kg N/ha for all
cultivars and often growth increased up to 105 kg N/ha. Optimum rates of N
for grain yield (Nopt) were lower and ranged, on
average, from 50 kg N/ha for Clipper to 96 kg N/ha for Chebec. The
initial response to N varied from 13–14 kg/kg N in Chebec, Weeah and
Schooner, to 36 kg/kg N in Skiff.
The Nopt for the semi-dwarf cultivar Skiff was 71 kg
N/ha and it tended to show the greatest yield response to N. It produced
19 kernels/g DMee, compared with 15–17
kernels/g DMee in the other cultivars. Unlike most
other cultivars, Skiff’s yield was consistently and positively
correlated with ears/m2; Stirling was the only other
cultivar to show a similar relationship. However, the average kernel weight of
Skiff was up to 5 mg lower than that of Clipper, Weeah and Schooner, and
varied more than these cultivars between sites, suggesting that consistent
grain size may be a problem in this cultivar. By comparison, Clipper and
Schooner had lower Nopt (51 kg/ha) and a less
variable kernel weight.
There were no signs of differences in GPC of the 6 cultivars used here at 3
N-responsive sites. Adding N increased GPC up to the highest rate of N and the
responses were generally linear, but GPC at Nopt
exceeded the upper limit for malting quality of 11.8% in all cultivars.
Average N rates of between 38 kg N/ha (Schooner) and 58 kg N/ha
(Skiff) were sufficient to raise GPC above 11.8%.
The experiments showed that the N rates for optimum yields varied considerably
among cultivars, but applyi1ng rates to achieve maximum yields may cause GPC
to exceed the maximum value for malting barley. The use of semi-dwarf
cultivars, such as Skiff, which are very responsive to N, can provide some
leeway in the choice of N, but there may be a trade-off in quality associated
with reduced grain size.
Effects of modifying layer cages with solid sides on stress physiology, plumage, pecking and bone strength of hens
Authors: Barnett J. L. , Glatz P. C. , Newman E. A. , Cronin G. M.
Published: August 2004

Summary. This experiment evaluated the welfare of layer
hens housed in cages modified with solid sides. Welfare was assessed on the
basis of physiological measures of stress [corticosterone concentrations
‘at rest’ and in response to adrenocorticotrophic hormone (ACTH)
and heterophil : lymphocyte ratios)] and immunological responsiveness,
feather condition and cover, bone strength, claw length and between-bird
pecking behaviour. Factors examined were cage modification (solid sides
v. open sides i.e. standard cages), tier (upper
v. lower), birds (1 or 2 birds/cage) and age
(commencing at 35 v. 60 weeks of age). The cages
provided a floor area of 1504 cm2. Floor pens (2.5 by
2.5 m) with 10 birds/pen served as an external control treatment.
Solid sides in cages reduced the level of stress, compared with both standard
cages and floor pens, based on lower corticosterone concentrations (2.2
v. 3.4 and 4.4 nmol/L, respectively) and lower
heterophil : lymphocyte ratios (1.36 v. 1.66 and 1.66,
respectively) (P<0.05). The ACTH response data
reflected a lower level of stress in the solid side compared with the pen
treatment (P<0.05). Feather condition and cover were
improved by the presence of solid sides compared with standard cages
(P<0.05), were similar to the floor pen treatment and
were probably a consequence of reduced pecking behaviour both within
(65%) and between cages (86%) (P<0.05).
Solid sides had no effects on immunological responsiveness, claw length or
bone strength. The experiment showed that solid sides can have a positive
effect on welfare by reducing the level of stress, decreasing between-bird
pecking and improving feather condition and cover. However, another study
showed mortalities increased in cages with solid sides during hot weather.
Zinc treatments applied to cassava (Manihot esculenta Crantz) setts changes early growth and zinc status of plants
Authors: Fulton M. C. , Asher C. J.
Published: August 2004

Summary. Zinc (Zn) deficiency limited the early growth
of cassava (Manihot esculenta Crantz) in nutritional
trials on a Zn-deficient lateritic red earth that was replaced after bauxite
mining at Weipa (12°28"S, 141°53"E). The symptoms developed
at 2 weeks after emergence, despite the band application of 0–32 kg
Zn/ha and were not related to rates of Zn or other fertilisers applied to
the soil. The Zn deficiency in the cassava plants was attributed to low Zn in
setts before root access to soil and fertiliser Zn.
Two techniques were studied to establish if they could be used to correct Zn
deficiency early in the growth of cassava: one was the fertilisation of
cassava plants before cutting the stems for planting setts, and the other was
soaking cassava setts in Zn solutions for various times at 101 kPa
(atmospheric pressure) or 51 kPa (partial pressure). Setts, after treatments,
were planted into pots of lateritic soil from Weipa.
Plants grown from setts soaked in ZnSO4 solutions
varying from 17.4 to 348 mmol Zn/L did not develop Zn-deficiency symptoms,
whereas, 62% of plants grown from either unsoaked setts or setts soaked
in water developed symptoms. However, the prior fertilisation of cassava
plants failed to decrease the incidence of Zn deficiency in plants and did not
increase the Zn concentration in setts.
Several treatments in Zn solutions were found to significantly increase the Zn
concentration in setts, were not detrimental to shoot emergence nor the
subsequent growth of plants, and provided an adequate Zn concentration in leaf
blades. These treatments were: soaking in 17.4 or 69.5 mmol Zn/L for 5 h
and in 69.5 mmol Zn/L for 0.5 h at 51 kPa; and soaking in 69.5 mmol
Zn/L for 5 h and in 139 mmol Zn/L for 0.5 and 5 h at 101 kPa. These
treatments could be used to overcome early Zn deficiency in cassava plants
where the deficiency is a problem despite the soil application of Zn
fertilisers.
Blackheart resistance in three clones of pineapple [Ananas comosus (L.) Merr.] in subtropical Queensland
Authors: Sanewski G. M. , Giles J.
Published: August 2004

Summary. Smooth Cayenne Queensland clone 13, and
intergroup hybrids 53-116 and 73-50 were harvested in mid July 1994 and
evaluated for blackheart resistance. Relative to C13, hybrids 73-50 and 53-116
had some level of field resistance to blackheart but only 53-116 was without
blackheart after storage at 10°C for 14 days followed by 20°C for 8
days. Hybrid 53-116 had a high vitamin C content compared with clone 13.
However, 73-50 had the highest level of vitamin C but still developed
blackheart, although the symptoms were not as severe as C13. This indicates
that factors other than vitamin C may play a role in blackheart resistance.
The level of field resistance to blackheart shown by 73-50 may be sufficient
for winter production in some sites in south-east Queensland. Field testing is
needed to determine the value of this resistance.
Survival of Pseudomonas syringae pv. pisi in soil and on pea trash and their importance as a source of inoculum for a following field pea crop
Authors: Hollaway G. J. , Bretag T. W.
Published: August 2004

Summary. The importance of soil and field pea trash as
sources of Pseudomonas syringae pv.
pisi for infection of field pea was investigated both in
a controlled environment and in the field. Studies of the survival of
P. syringae pv. pisi in soil using
autoclaved and non-autoclaved soil found that
P. syringae pv. pisi is unlikely
to survive in soil from one season to the next suggesting that soil is an
unlikely source of inoculum in the field. However,
Pseudomonas syringae pv. pisiwas
able to survive on buried pea trash for at least 29 weeks and on pea trash
positioned on the soil surface for at least 78 weeks. In a field trial, the
presence of pea trash naturally infected with
P. syringae pv. pisi caused
significant bacterial blight and reduced grain yield of a field pea crop by
25%. Therefore, pea trash is a potent source of inoculum and crop
rotations which include 2 seasons free of field peas should be considered as
part of a strategy to control bacterial blight.
The agronomic effectiveness of reactive phosphate rocks 1. Effect of the pasture environment
Authors: Sale P. W. G , Gilkes R. J. , Bolland M. D. A. , Simpson P. G. , Lewis D. C. , Ratkowsky D. A. , Gilbert M. A. , Garden D. L. , Cayley J. W. D. , Johnson D.
Published: August 2004

Summary. The agronomic effectiveness of directly applied
North Carolina reactive phosphate rock was determined for 4 years from annual
dry matter responses at 26 permanent pasture sites across Australia as part of
the National Reactive Phosphate Rock Project. Fertiliser comparisons were
based on the substitution value of North Carolina reactive phosphate rock for
triple superphosphate (the SV50). The
SV50 was calculated from fitted response curves for both
fertilisers at the 50% of maximum yield response level of triple
superphosphate. The reactive phosphate rock was judged to be as effective as
triple superphosphate in the 1st year (and every year thereafter) at 4 sites
(SV50 >0.9), and was as effective by the 4th year at
5 sites. At another 9 sites the reactive phosphate rock was only moderately
effective with SV50 values between 0.5 and 0.8 in the
4th year, and at the final 8 sites it performed poorly with the 4th year
SV50 being less than 0.5. Pasture environments where the
reactive phosphate rock was effective in the 1st year were: (i) those on
sandy, humic or peaty podsols with an annual rainfall in excess of 850 mm;
(ii) those on soils that experienced prolonged winter inundation and lateral
surface flow; and (iii) tropical grass pastures in very high rainfall areas
(>2300 mm) on the wet tropical coast on North Queensland. The highly
reactive North Carolina phosphate rock became effective by the 4th year at
sites in southern Australia where annual rainfall exceeded 700 mm, and where
the surface soil was acidic [pH (CaCl2)
<5.0] and not excessively sandy (sand fraction in the A1 horizon
<67%) but had some phosphorus (P) sorption capacity. Sites that were
unsuitable for reactive phosphate rock use in the medium term (up to 4 years
at least) were on very high P-sorbing krasnozem soils or high P-sorbing
lateritic or red earth soils supporting subterranean-clover-dominant pasture,
or on lower rainfall (< 600 mm) pastures growing on soils with a sandy A1
horizon (sand component >84%). No single environmental feature
adequately predicted reactive phosphate rock performance although the surface
pH of the soil was most closely correlated with the year-4
SV50 (r = 0.67). Multiple
linear regression analysis found that available soil P (0–10 cm) and the
P sorption class of the surface soil (0–2 cm), together with annual
rainfall and a measure of the surface soil"s ability to retain moisture,
could explain about two-thirds of the variance in the year-4
SV50 . The results from this Project indicate that there
are a number of specific pasture environments in the higher rainfall regions
of Australia where North Carolina reactive phosphate rock can be considered as
an effective substitute P fertiliser for improved pasture.
The agronomic effectiveness of reactive phosphate rocks 5. The effect of particle size of a moderately reactive phosphate rock
Authors: Babare A. M. , Sale P. W. G. , Fleming N. , Garden D. L. , Johnson D.
Published: August 2004

Summary. The effect of particle size on the agronomic
effectiveness of a moderately reactive phosphate rock (from the Hamrawein
deposit in Egypt) was investigated at 4 of the field sites in the National
Reactive Phosphate Rock Project. The aim of these experiments was to determine
whether the agronomic effectiveness of this fertiliser was increased by
removing particles greater than 0.5 mm in diameter (these coarser particles
constituted 28% of the fertiliser). The more reactive North Carolina
phosphate rock was used as a reference fertiliser. Soils from 3 of the field
sites were also used for glasshouse experiments. The forms of Hamrawein
phosphate rock used in these experiments were the less than 0.50 mm particle
size fraction (as was used in the field experiments), the 0.075–0.15 mm
fraction, and the less than 0.50 mm particle size fraction finely ground.
Subterranean clover was used as the test plant and North Carolina phosphate
rock and monocalcium phosphate were used as reference fertilisers. A series of
laboratory experiments were also undertaken to investigate the effect of
particle size.
The agronomic effectiveness of Hamrawein phosphate rock was not affected by
the different particle size treatments used in the field and glasshouse
experiments. The Hamrawein phosphate rock was about equal in effectiveness to
North Carolina phosphate rock at the high rainfall leaching site that had
acidic sandy soil, and was less effective than North Carolina phosphate rock
at the other 2 field sites. The Hamrawein phosphate rock was similar in
effectiveness to North Carolina phosphate rock and monocalcium phosphate in
the glasshouse experiments with the 2 low P-sorbing soils and was much less
effective than North Carolina phosphate rock and monocalcium phosphate in the
high P-sorbing soil. Laboratory studies found that there were minimal
differences in the amount and rate of dissolution of different particle size
fractions of the Hamrawein phosphate rock in moist incubated soil. Free
carbonate, most likely in the form of dolomite, was found in all particle size
fractions of the Hamrawein phosphate rock and was particularly concentrated in
the particle size fractions less than 0.15 mm. This fine dolomite fraction may
have suppressed the extent that Hamrawein phosphate rock dissolves in soil,
and may have negated any potential beneficial effect that reducing particle
size by sieving or by grinding may have had on the agronomic effectiveness of
Hamrawein phosphate rock in the field and glasshouse experiments.
Agronomic effectiveness of a partially acidulated reactive phosphate rock fertiliser
Authors: Lewis D. C. , Sale P. W. G. , Johnson D.
Published: August 2004

Summary. The agronomic effectiveness of a partially
acidulated phosphate rock (PAPR), produced by the 50% acidulation of
North Carolina phosphate rock with sulfuric acid, was compared over 4 growing
seasons with triple superphosphate (TSP) and the highly reactive North
Carolina phosphate rock at 22 permanent pasture sites in the National Reactive
Phosphate Rock Project. The performance of PAPR as a phosphorus (P) fertiliser
for permanent pasture was determined by calculating the substitution value of
TSP for PAPR at 50% of the maximum yield response for TSP from the
fitted annual dry matter response curves. PAPR performance varied both between
sites, and between years at individual sites. Annual yield responses with PAPR
were larger than those with TSP at 1 high rainfall site where water-soluble P
from TSP was thought to leach from the root zone. PAPR was superior to TSP at
another site and generally similar in effectiveness to TSP at 4 sites with
light-textured, low or medium P-sorbing soils with a moderate annual rainfall
(500–750 mm). The mean substitution value over the 4 years for these
sites was >0.9. PAPR performance at other sites where highly reactive
phosphate rocks were effective in the short or medium term was variable: there
were equivalent yield responses to TSP in some years but much smaller yield
responses in other years. PAPR performed very poorly in a third group of sites
where the soil had a high to very high P sorption capacity or where there was
a very high demand for fertiliser P due to large legume responses on a
P-deficient soil. Although generally inferior to TSP, the PAPR was more
effective than North Carolina phosphate rock at the majority of sites during
the 4-year study.
Soil sulfur status, sulfur fertiliser responses and rainfall sulfur accessions at trial sites in the National Reactive Phosphate Rock Project
Authors: Anderson G. , Blair G. J. , Crestani M. , Lewis D.
Published: August 2004

Summary. The sulfur (S) status of the National Reactive
Phosphate Rock Project trial sites was determined using 2 chemical extractants
KCl-40 (0.25 mol KCl/L heated to 40°C) and MCP (0.01 mol mono-calcium
phosphate/L). There were marked differences between sites in KCl-40-
extractable S down the soil profile. Soil profiles were classified into 4
groups according to the shape of the extractable S profile. KCl-40 was better
able to distinguish between responsive (significant at P
= 0.10 only) and unresponsive sites than MCP.
Mean S accession in rainfall over the 3 years ranged from 0.40 kg/ha .
year at Jericho (site T17) in the centre of Tasmania to 20.33 kg/ha . year
at Smithton (site T16) on the north-west coast of Tasmania. The proportion of
S-responsive sites increased from 26% in the first year to 43, 42 and
48% in years 2, 3 and 4 respectively. Such a large proportion of
S-responsive sites limits the use of direct application of reactive phosphate
rock fertiliser.
Effects of phosphate rock products on soil pH
Authors: Lewis D. C. , Hindell R. P. , Hunter J.
Published: August 2004

Summary. Changes to soil pH (CaCl2
) following annual applications of phosphate rock (PR) and water-soluble
phosphorus products were investigated in the National Reactive Phosphate Rock
Project. It was difficult to measure small changes in pH due to variation in
pH within each site and across years. pH (the change over time from the
initial soil pH at that plot) was significantly influenced by fertiliser
product at 13 of the 27 sites examined. At 5 sites, one or more of the PR
products had pH of 0.07–0.21 units greater than the pH of the control.
At the other 8 sites, the pH of the control plot was greater than or equal to
the that of the PR plots, or significant increases in pH occurred in the
single superphosphate plots. The changes in soil pH following application of
the fertiliser products were inconsistent both within and between sites.
Chemically the PR products have the potential to reduce the rate of
acidification in soils where the products dissolve readily, however, this was
not generally reflected in the field, where the application of PR products
only increased soil pH at a limited number of sites.
Effect of fertiliser type on cadmium and fluorine concentrations in clover herbage
Authors: McLaughlin M. J. , Simpson P. G. , Smart M. K. , Fleming N. , Stevens D. P. , Cozens G.
Published: August 2004

Summary. This study investigated whether changing
phosphatic fertiliser type affects the accumulation of cadmium (Cd) and
fluorine (F) in pasture herbage. North Carolina phosphate rock, and partially
acidulated fertilisers derived from this rock, generally have higher Cd and F
concentrations compared with single superphosphate currently manufactured in
Australia.
Clover herbage from sites of the National Reactive Phosphate Rock trial was
collected and analysed for concentrations of Cd (11 sites) and F (4 sites). A
comparison was made between pastures fertilised with 4 rates of single
superphosphate, North Carolina phosphate rock, and partially acidulated
phosphate rock having Cd concentrations of 283, 481 and 420 mg/kg P
respectively, and F concentrations of 170, 271 and 274 g/kg P
respectively. One site used Hamrawein (Egypt) phosphate rock (HRP) having a Cd
and F concentration of 78 mg Cd/kg P and 256 g F/kg P respectively. To
help identify differences in herbage Cd concentrations between sites,
unfertilised soils from each site were analysed for total and extractable Cd
contents. At one site Cd concentrations in bulk herbage (clover, grasses and
weeds) were related to infestation of the pasture by capeweed
(Arctotheca calendula L. Levyns).
There were no significant differences between F in herbage from plots
fertilised with either single superphosphate, partially acidulated phosphate
rock or North Carolina phosphate rock, or between sites. Concentrations of F
in herbage were low, generally less than 10 mg/kg. However, there were
large differences in Cd concentrations in herbage between sites, while
differences between fertiliser treatments were small in comparison. The site
differences were only weakly related to total or extractable (0.01 mol
CaCl2/L) Cd concentrations in soil.
Significant differences in Cd concentrations in clover due to fertiliser type
were found at 5 sites. North Carolina phosphate rock treatments had
significantly higher Cd concentrations in clover compared with single
superphosphate at 2 sites. Partially acidulated phosphate rock treatments had
significantly higher Cd concentrations in clover compared with single
superphosphate at 4 sites. At the site where Hamrawein was tested, this
treatment had significantly lower Cd concentrations in clover compared with
both single superphosphate and North Carolina phosphate rock treatments.
Building an expert system to advise on the use of reactive phosphate rock on Australian pastures
Authors: Gillard P. , Sale P. W. G. , Tennakoon S. B.
Published: August 2004

Summary. An expert system has been developed, using the
results from the National Reactive Phosphate Rock Project, to determine
whether reactive phosphate rock is likely to be an effective substitute for
water-soluble superphosphate fertiliser for a given pasture environment. The
evaluation is made from site information [annual rainfall, pasture
composition and the likelihood of phosphorus (P) leaching], and soil
information (pH, Colwell P, soil colour and field texture). The expert system
can determine the effectiveness of both highly reactive and moderately
reactive phosphate rocks. Observed substitution values of triple
superphosphate for the highly reactive North Carolina phosphate rock (ratio of
the respective P levels required to produce 50% of the maximum observed
yield response to triple superphosphate) were closely related to values
predicted by the expert system (r = 0.92); the
relationship between observed and predicted substitution values of single
superphosphate for the moderately reactive Hemrawein phosphate rock was also
close (r= 0.86). The expert system gives one of 4
different recommendations for reactive phosphate rock based on the magnitude
of the predicted substitution values. These are ‘immediately
effective’, ‘effective in the medium term’,
‘marginally effective’, and ‘not effective’. The
system was validated using the results from independent field experiments that
provided measures of the effectiveness of reactive phosphate rock at different
pasture sites.
An appraisal of the National Reactive Phosphate Rock Project
Authors: Reuter D. J.
Published: August 2004

Summary. An expert system has been developed, using the
results from the National Reactive Phosphate Rock Project, to determine
whether reactive phosphate rock is likely to be an effective substitute for
water-soluble superphosphate fertiliser for a given pasture environment. The
evaluation is made from site information [annual rainfall, pasture
composition and the likelihood of phosphorus (P) leaching], and soil
information (pH, Colwell P, soil colour and field texture). The expert system
can determine the effectiveness of both highly reactive and moderately
reactive phosphate rocks. Observed substitution values of triple
superphosphate for the highly reactive North Carolina phosphate rock (ratio of
the respective P levels required to produce 50% of the maximum observed
yield response to triple superphosphate) were closely related to values
predicted by the expert system (r = 0.92); the
relationship between observed and predicted substitution values of single
superphosphate for the moderately reactive Hemrawein phosphate rock was also
close (r= 0.86). The expert system gives one of 4
different recommendations for reactive phosphate rock based on the magnitude
of the predicted substitution values. These are ‘immediately
effective’, ‘effective in the medium term’,
‘marginally effective’, and ‘not effective’. The
system was validated using the results from independent field experiments that
provided measures of the effectiveness of reactive phosphate rock at different
pasture sites.
The effect of phosphate buffering capacity and other soil properties on North Carolina phosphate rock dissolution, availability of dissolved phosphorus and relative agronomic effectiveness
Authors: Babare A. M. , Gilkes R. J. , Sale P. W. G.
Published: August 2004

Summary. The dissolution of North Carolina phosphate
rock (NCPR) in soil was investigated in a laboratory study using surface soils
sampled from 28 permanent pasture sites. The relationships between phosphorus
(P) dissolved, P availability and various soil properties were investigated
using simple and multiple linear regression and the findings related to the
relative effectiveness of NCPR for pasture production at the sites. The extent
of dissolution of NCPR was positively correlated to P buffering capacity
(r2 = 0.42). Phosphorus
buffering capacity and titratable acidity together accounted for 72% of
the variance in dissolution. Bicarbonate-extractable P
(‘available’ P) generally increased as dissolution increased.
However, the increase in available P was consistently lower for soils with
higher P buffering capacity. The proportion of dissolved P that was available
also decreased with increasing P buffering capacity
(r2 = 0.63). Consequently,
the increase in available P was highest for soils with very low to low P
buffering capacity. This suggests that the effectiveness of NCPR as a
fertiliser may be more closely related to the availability of dissolved P,
than to the amount of NCPR dissolved in a soil. Consistent with this
laboratory finding, the agronomic effectiveness of NCPR relative to
superphosphate measured in the field tended to decrease with increasing P
buffering capacity. The agronomic effectiveness of NCPR was comparable with
superphosphate only at certain sites, and with some noted exceptions, most of
these had surface soils with very low to low P buffering capacity. The high
relative effectiveness of NCPR at these sites was mostly attributed to the
loss of superphosphate by leaching. Since NCPR dissolves much more slowly than
superphosphate, only a small amount of the P applied as NCPR would be lost
during leaching events. Slow dissolution of the remaining NCPR probably
supplied a small amount of dissolved P over an extended period of time, and
due to the low P buffering capacity, much of this was available to plants.
Long-term stocking rate effects on soil physical properties
Authors: Greenwood K. L. , MacLeod D. A. , Hutchinson K. J.
Published: August 2004

Summary. The effects of sheep stocking rate on soil
physical properties were investigated in a long-term (>30-year-old) grazing
trial on the Northern Tablelands of New South Wales. The soil physical
properties studied were unsaturated hydraulic conductivity, soil strength and
bulk density. Significant differences between the ungrazed and grazed pastures
were found for all soil physical measurements. Compaction by sheep was limited
to the upper 5 cm of the soil profile and resulted in lower porosity, mainly
due to loss of pores larger than 1.2 mm equivalent diameter.
However, after 30 years, the pastures grazed at 10, 15 and 20 sheep/ha had
similar soil physical properties. Soil physical properties appear to be
relatively insensitive to stocking rate in the long term and therefore other
factors, such as maintenance of pasture cover, should be given a higher
priority in grazing management decisions.
Supplements improve the production of dairy cows grazing either white clover or paspalum-dominant pastures in late lactation
Authors: Stockdale C. R.
Published: August 2004

Summary. Thirty-six Friesian cows in late lactation,
with an initial average daily milk yield of 15.4 kg/day, grazed pure white
clover (Trifolium repens cv. Haifa) or paspalum
(Paspalum dilatatum)-dominant swards for up to 6 weeks
in autumn and were supplemented with maize (Zea mays)
silage with or without barley grain, urea or cottonseed meal. Five groups of 4
cows were offered about 21 kg dry matter (DM)/cow. day of
paspalum-dominant pasture. One group was unsupplemented while the other groups
were offered one of the following supplementary feeding treatments: (i) 5 kg
DM/cow of maize silage; (ii) 5 kg DM/cow of maize silage and 75 g of
urea; (iii) 3 kg DM/cow of maize silage plus 2 kg DM of rolled barley; or
(iv) 3 kg DM/cow of maize silage plus 2 kg DM of cottonseed meal each day.
A further 4 groups of 4 cows were offered 21 kg dry matter/cow. day of
white clover pasture, and the same supplement treatments, with the exception
of maize silage–cottonseed meal. All cows were individually fed their
supplement but they grazed the pastures as groups according to treatment.
Cows offered white clover and no supplements ate 12.9 kg DM/cow.day of
herbage and maintained milk production. All supplements increased total DM
intake and improved milk production, to about 18 kg/cow. day, with a mean
marginal response of 0.8 kg of milk per 1.0 kg of extra total DM eaten. There
were no differences in production due to the type of supplement.
Cows grazing paspalum ate less pasture, and levels of substitution of pasture
by supplement were higher than when white clover was fed. Milk yields of the
unsupplemented cows dropped rapidly and consistently with the cows virtually
ceasing production. All supplements successfully arrested the decline in milk
production, and to about the same degree; the marginal response to extra
feeding was 1.4 kg of milk for each kilogram of additional total DM eaten.