bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of chelating agents on the performance of growing chickens fed high calcium diets
Authors: Shafey TM
Published: March 2005

The effects of supplementation with chelating agents on the growth performance of chickens fed high calcium diets were investigated in 2 experiments. In experiment 1, increasing dietary calcium to 25.2 g/kg significantly reduced body weight gain and feed efficiency. The addition of phytic acid (10 g/kg) tended to improve body weight gain of chickens fed high calcium diets; however, the gain was not significantly different from that of birds fed the high calcium diet. The addition of either Na2EDTA (1 g/kg) or proline (10 g/kg) to a high calcium diet did not affect body weight gain or feed efficiency of chickens. In experiment 2, increasing dietary calcium to 26 g/kg significantly reduced body weight gain and feed efficiency and increased plasma total calcium concentration. The addition of cellulose significantly (P<0.01) reduced plasma calcium and tibia calcium concentrations; however, the performance of chickens fed high calcium diets was not affected by the addition of cellulose. It was concluded that chelating agents differ in their ability to eliminate the toxic effects of high calcium diets, and that the addition of phytic acid at 1% was most successful in eliminating the growth depressing effect of high dietary calcium.
Response of defoliated swards of subterranean clover and yellow serradella to superphosphate applications
Authors: Bolland MDA
Published: March 2005

The effect of superphosphate applications (0, 25, 50, 75, 100 and 125 kg P/ha to the soil surface) on the dry matter (DM) herbage production of dense swards of subterranean clover (Trifolium subterraneum cv. Junee) and yellow serradella (Ornithopus compressus cv. Tauro) was measured in a field experiment on deep, sandy soil in south-western Australia. The swards were defoliated with a reel mower at weekly intervals from 88 to 158 days after sowing, to a height of 2 cm for the first 9 cuts, 4 cm for the tenth cut and 5 cm for the eleventh cut. Yellow serradella was more productive than subterranean clover. Consequently, for the relationship between yield and the level of phosphorus (P) applied, yellow serradella supported larger maximum yields and required less P than subterranean clover, to produce the same DM herbage yield. Maximum yields of yellow serradella were 12-40% larger. To produce 70% of the maximum yield for yellow serradella at each harvest, yellow serradella required about 50% less P than subterranean clover. However, when yields were expressed as a percentage of the maximum yield measured for each species at each harvest, the relationship between yield and the level of P applied was similar for both species, and they had similar P requirements.
Soil solarisation combined with low rates of soil fumigants controls clubroot of cauliflowers, caused by Plasmodiophora brassicae Woron
Authors: Porter IJ , Merriman PR , Keane PJ
Published: March 2005

The effect of solarisation combined with low rates of soil fumigants on the severity of clubroot and yield of cauliflowers was determined at 2 locations in southern Victoria. The effectiveness of treatments was shown to be dependent on location; on the type, water content and temperature of soil; and on the population density of Plasmodiophora brassicae. Yields were reduced depending upon the disease severity, usually within 60 days after transplanting. Propagules of P. brassicae could survive for more than 28 days in ovens at 45�C when in dry soil but died within 14 days at 40�C in moist soil. At Werribee in 1985 on a red brown earth, solarisation combined with dazomet (100 kg dazomet/ha) gave significantly better control than either treatment alone. This treatment reduced P. brassicae in the 0-10 cm layer, reduced the disease rating from 2.7 to 0.9 (0-3), and increased yield from 2.4 to 47 t/ha compared with controls. In 1986, solarisation combined with 98% methyl bromide-2% chloropicrin (100 and 250 kg/ha) reduced the population density of P. brassicae in the 0-10 and 10-20 cm layers of soil, reduced the disease rating from 3 to 1.8, and increased yield from 0 to 22 t/ha. These treatments were more effective than solarisation and dazomet used alone or in combination. At Keysborough in 1985 on a grey sand, separate treatments of solarisation or dazomet (100 and 250 kg dazometha) were as effective as combined treatments and significantly reduced disease and increased yields compared to controls. Solarisation combined with either fumigant significantly reduced the distribution and total number of weeds at all sites and was generally more effective than separate treatments.
Effect of aphids and mites on herbage and seed production of subterranean clover (cv. Daliak) in response to superphosphate and potash
Authors: Brennan RF , Grimm M
Published: March 2005

The dry matter production (DM) and seed yield of subterranean clover (Trifolium subterraneum L. cv. Daliak) were reduced by infestations of redlegged earth mite (Halotydeus destructor Tucker) and blue-green aphid (Acyrthosiphon kondoi Shinji) during spring growth, flowering and burr burial. The dominance of these pests varied with season. The effects of spraying with insecticides on the DM and seed yield responses to superphosphate and potassium chloride fertilisers were measured. Responses to superphosphate were described by Mitscherlich functions for each of 3 levels of potassium chloride, except for seed yields with pest sprays. At optimum levels of superphosphate and potassium chloride, controlling pests increased DM by up to 150% (from 4.37 to 6.52 t/ha). For all levels of superphosphate, spraying to control pests where no potassium chloride was applied significantly increased DM over that on unsprayed plots that were fertilised with potassium chloride. The maximum DM response to superphosphate application was achieved at 15-20 kg P/ha. With optimum superphosphate, the value for DM depended on the combination of spraying for pests and amount of potassium chloride applied, generating a series of Mitscherlich response curves for superphosphate application with differing maximum yields. With optimum superphosphate applied, the least DM recorded within a season was 3.47 t/ha (pests not sprayed, nil potassium chloride), and the most was 6.52 t/ha (pests sprayed, 120 kg potassium chloride/ha), an increase of about 180%. At optimum levels of superphosphate and potassium chloride, controlling pests increased seed yield by up to 380% (from 290 to 1100 kg/ha). With optimum superphosphate, seed yield within a season ranged from 210 (pests not sprayed, nil potassium chloride) to 1100 kg/ha (pests sprayed, 120 kg potassium chloride/ha), an increase of 524%. With pests sprayed, seed yield declined with superphosphate applications >20 kg P/ha; the relationship was best described by a quadratic function. With pests not sprayed, seed yield did not decline with increasing amounts of superphosphate, and the relationship fitted a Mitscherlich function.
Comparative yield performance of wheat cultivars grown in small and bulk-sized plots
Authors: Lewis GJ , D'Antuono MF
Published: March 2005

The ranking and grain yield of several recently released and superseded wheat cultivars grown in standard-sized (35-40 m2) plots were compared with their ranking and yield in similarly treated and adjacent bulk-sized plots (0.25-1 ha) in 6 environments in Western Australia. Three of the cultivars were tall (average 83.6 cm) and 3 were semidwarf (average 7 1.5 cm). The yield of cultivars in standard-sized plots was highly correlated (P<0.01) with their yield performance in bulk areas. There were 2 distinct groups of environments. In the first group there was no difference between yields in the standard-sized and bulk-sized plots. In the second group, which consisted of environments with mean yields >2 t/ha, the yield of wheat grown in standard-sized plots was up to 1.0 t/ha higher than the yield in bulk-sized plots. Cultivars had a similar pattern of yield performance in standard and bulk-sized plots, regardless of any differences in plant height.
Micropropagation of an Australian terrestrial orchid Diuris longifolia R. Br
Authors: Collins MT , Dixon KW
Published: March 2005

A method is described for the in vitro propagation of the Australian terrestrial orchid Diuris longifolia R. Br. Explants from inflorescences of D. longifolia were successfully cultured on modified Burgeffs N3f containing the cytokinin N6 benzyladenine. Protocorm-like bodies formed after 49 days on explants taken from the basal section of flower buds and axillary nodes from inflorescences. Root formation occurred 70 days after transfer of 10-20-rnm-long shoots onto medium containing coconut water and no cytokinin, and rooted plantlets were transferred to soil and acclimatised 2-3 weeks later. Rooting of in vitro shoots was improved by increasing the sucrose concentration to 40 g/L or by addition of 0.05% activated charcoal to the culture medium. Plantlets developed flowering stems in vitro and flowered in pots 11 months after excision of explants from the parent plant. This tissue culture method has been successfully applied to the propagation of D. purdiei, a rare and threatened species from Western Australia.
Extending the frontiers of aerially sown pastures in temperate Australia: a review
Authors: Campbell MH
Published: March 2005

Over the past 40 years large areas of pastures on hill country in temperate Australia have been improved through aerial distribution of herbicides, pesticides, seed, and fertiliser, which has increased animal production and helped to control weeds. Refinements detailed in this review could extend the use of these techniques to promote sustainable systems by the establishment of perennial pasture species on unploughed land. It is argued that the most urgent requirement is ensuring that aerial spraying is not abolished by government regulation in response to demands by specialist groups, because perennial pasture species will not establish on hill country without prior aerial spraying of herbicides. The major technical refinement needed is the reduction of losses of establishing plants due to weed competition and dry periods during their first spring and summer. This could be accomplished by increasing the spectrum of weeds controlled by the most widely used herbicide, glyphosate; applying new herbicides that give longer weed control in spring than the presently used herbicides; using herbicides that can selectively remove annual grass weeds from establishing perennial grasses; or using strategic grazing with cattle or goats to reduce weed competition. Breeding, selecting or importing pasture species specifically designed for establishment from surface sowing has never been attempted. Attributes that could improve establishment include germination that occurs only under favourable conditions; seeds resistant to weathering on the soil surface; seedlings with fast radicle entry, hairs on the radicle, fast root development, and better seedling vigour; and for subtropical species sown in semi-arid New South Wales, tolerance of low winter temperatures. Improved distribution of herbicides, seeds and fertilisers, particularly in the more rugged hill country, is needed to ensure complete cover of the treated area with minimum drift. Techniques that allow establishment of aerially sown pastures on hill country with very acid soil are needed to facilitate the development of further, large areas of Australia.
Plant population studies on peanut (Arachis hypogaea L.) in subtropical Australia. 3. Growth and water use during a terminal drought stress
Authors: Wright GC , Bell MJ
Published: March 2005

Two peanut cultivars of different botanical type (Virginia and Spanish) were grown at 3 plant population densities (40000, 120000 and 240000 plants/ha) and relied solely on stored soil water in a deep kraznozem soil for water requirements. Protracted crop water deficits occurred from flowering to maturity. Plant population influenced both the temporal and spatial patterns of water use, with high density crops extracting water from lower depths sooner than low density crops. Higher water use prior to early podfilling in high density crops was associated with more rapid leaf area development. Reproductive development was strongly influenced by plant population density, with more pods per m2 in low than in high density crops. Lower leaf water potential and individual leaf photosynthetic rates in the middle of the day during the pegging and early podding phase suggested that high crop water deficits had lowered assimilate availability and reduced reproductive potential in high, compared with low, density crops. The results indicate that there is scope for increasing pod yield when peanut is growing solely on stored water, by reducing plant population. The timing of water use, as distinct from the amount of water used, was the major determinant of pod yield.
Metalaxyl and phosphonate as prophylactic and curative agents against stem infection of Leucadendron caused by Phytophthora cinnamomi
Authors: Marks GC , Smith IW
Published: March 2005

Neither metalaxyl (100 mL of a solution of 2.0 g a.i./L, applied as a root drench to 10-L pots) nor phosphonate (foliar spray at 1.0 g a.i./L, applied to runoff) controlled Phytophthora cinnamomi stem infection of Leucadendron laureolum x L. salignum hybrid when applied 10 days after inoculation. Both fungicides were most effective when applied prior to inoculation. Neither fungicide was able to kill P. cinnamomi within established infections. The fungus survived within the vascular tissues of treated plants. Infection was confined to cortical tissue by wound periderm when the rate of tissue invasion by P. cinnamomi was slowed by the fungicides. The results confirm observations made in protea growers' fields that with highly susceptible species, systemic fungicides can have poor curative properties and should be used as a prophylactic, in conjunction with other disease control methods.
Supplementation of young sheep with lupins plus sulfur and a complete mineral mix
Authors: Doyle PT , Love RA , Dunlop RH , White CL
Published: March 2005

Young Merino sheep (7-8 months of age, weighing about 40.5 kg) were given weekly supplements of 1050 gfsheep of lupins, lupins coated with potassium sulfate (25 g/kg lupins), lupins and access to a mineral lick (offered at 175 g/sheep.week), or lupins coated with potassium sulfate and access to the lick. The sheep grazed an annual pasture at a stocking rate of 15 sheepha and were given the supplements between 14 December and 5 April. The amount of pasture on offer in mid December exceeded 3000 kg DMha but declined to 1500 kg DMha in late March.There were significant amounts of green feed present in December and March (>20% of pasture DM), a small amount in January, and no green feed in February. Despite this the percentage of sheep licking the minerals was over 70% in January , February; and March, with average intake being about 10 g/sheep.day. No significant differences occurred between treatments for liveweights of sheep during the feeding period or at shearing. Over the feeding period sheep lost weight at about 30 g/day. Neither the additional sulfur nor the mineral lick had any significant effects on fleece weight, mean fibre diameter of the fleece, staple length, or staple strength. Wool growth rates were not different between treatments during the feeding period. These results indicate that under good pasture conditions with some green feed available, and when lupins are supplied, responses to mineral supplements are unlikely.
Maize silage for the pasture-fed dairy cow. 4. A comparison between grazed annual pastures and feedlotting in the winter
Authors: Moran JB , Wamungai WN
Published: March 2005

Dairy cows in early lactation grazed irrigated annual pastures during 14 weeks in autumn and winter. They were grazed for either 2 or 6 h each day and then restricted to a feedpad and offered ad libitum maize silage. Other cows were fed 1 of 2 diets while in yards: a feedlot diet based on cereal grain, maize silage, and protein supplement; a mixture of conserved legume and maize silage. Feed intakes and cow performance were monitored. Cows in metabolism cages were fed the feedlot diet with various combinations of red clover and maize silage. Digestibility and rate of disappearance of test feeds from nylon bags were measured in the metabolism trials. Rumen samples were analysed for pH, ammonia, and volatile fatty acids. Dietary constituents were evaluated in vitro and in vivo using sheep. The cows on the feedlot diet recorded the highest DM intakes and the highest liveweight gain, and initially produced the most milk and milk protein. Their milk yields eventually fell to levels similar to those of the grazing cows. Cow performance was poorest on the pasture silage-maize silage mixture, and this treatment was discontinued after only 8 weeks. The poor performance was partly attributed to reduced silage quality from heat damage during ensiling the pasture. Supplementing red clover with increasing levels of maize silage did not influence digestibility but reduced DM intakes and cow performance. Cows grazing for 2 h/day produced 1-2 L/day less milk, and lost more weight, than cows grazing for 6 h/day; their rumen ammonia fell below critical levels. The grazing of high-clover pastures between morning and afternoon milking, combined with maize silage supplementation, is convenient and sustains high milk yields during early lactation.
Persistence, productivity and seed yield of Medicago murex, M. truncatula, M. aculeata and Trifolium subterraneum on an acid red earth soil in the wheat belt of eastern Australia
Authors: Dear BS , Jenkins L
Published: March 2005

The persistence, productivity, and seed yield of 4 annual legume species, Trifolium subterraneum L. var. subterraneum, Medicago murex Willd, M. truncatula Gaertn var. truncatula, and M. aculeata, were compared on an acid red earth soil at Temora. New South Wales. All species persisted for 4 years but there were significant differences in herbage yields and seed reserves between species, and between cultivars and lines within species. The recently released T. subterraneum cultivar, Junee, produced superior seedling densities in 2 of the 3 regenerative years and maintained similar summer seed reserves, but carried over a higher proportion of seed (hard seed) through each winter and was as productive as the older cultivar, Woogenellup, except in late spring. The 6 M. murex lines persisted and remained well nodulated on the moderately acid [pH(CaCl2) 4.81 soil when grown with a new acid-tolerant Rhizobium strain, WSM 419. Medicago murex demonstrated potential as an alternative species to T. subterraneum for the eastern wheat belt; it maintained high seed reserves and was more hardseeded than T. subterraneum cultivars, but this did not reduce its ability to produce large populations of seedlings in autumn. While the M. aceuleata and M. truncatula lines demonstrated that they could persist and regenerate adequately over the 4-year period, neither proved to be superior to either the T. subterraneum or M. murex lines in any of the parameters.
Effect of time sowing and cultivar on the development and grain yield of irrigated wheat in the Macquarie Valley, New South Wales
Authors: Cooper JL
Published: March 2005

Field experiments over 2 seasons in the Macquarie Valley of central New South Wales compared yields under irrigation of 5 wheat varieties with a wide range of maturities sown from 8 April to 27 August.Early maturity wheats (Yecora and Avocet) sown prior to 6 May suffered frost damage, while the winter wheats (WW33G and Burgas) sown after 29 July were not fully vernalised and most tillers failed to produce heads. There was a curvilinear relation between time of sowing and grain yield. Excluding the treatments which suffered frost damage, the earliest time of sowing (8 April) produced the highest yield, with a 6.4% yield reduction between 8 April and 8 May. The yield reduction increased with later sowing date: 13.3, 19.3, and 26.5% during May, June, and July. Anthesis in mid September produced the highest yields for all varieties. Treatments which flowered earlier than mid September suffered frost damage. For each day later than 15 September that anthesis occurred, the mean yield fell by 1.3% or about 68 kg/ha.day. Date of anthesis had no detectable effect on the rate of individual grain growth (1.3 mg/grain.day), but the later anthesis occurred, the shorter the duration of grain development and the lower the final grain weight. Rising temperatures, not moisture stress, seems to be the factor causing the decline in yield with late sowing. This experiment was irrigated to eliminate moisture stress but the decline in yield was similar to that reported for dryland crops.
Recovery of fertiliser nitrogen in wheat grain and its implications for economic fertiliser use
Authors: Doyle AD , Leckie CC
Published: March 2005

Grain yield, protein, and nitrogen uptake responses are reported for 6 wheat fertiliser experiments in northern New South Wales which were representative of sites that were highly responsive, moderately responsive, and non-responsive to nitrogen (N) fertiliser applied at sowing. Apparent recoveries of applied N of 33-57% in the grain were recorded where grain yield was steeply increasing in response to additional applied N. Where yield increases were smaller in response to increments of N fertiliser, N recovery was 22-3096, but where further N application increased grain protein content but not grain yield, apparent recovery of additional fertiliser N fell below 20%. Apparent recovery was less than 10% in experiments where there was no yield response to N fertiliser. The implications for fertiliser recommendations are discussed relative to potential premium payment for wheat protein levels. It was concluded that established premium payments are too low to make N application an economic proposition to increase grain protein levels in the absence of grain yield responses.
Productivity of Hereford, highgrade Simmental and Belmont Red beef herds in central Queensland. 1. Pregnancy, calving and weaning rates
Authors: Burns BM , Tierney TJ , Rudder TH , Esdale CR , Howitt CJ , O'Rourke PK
Published: March 2005

Reproductive rates of Hereford, highgrade Simmental and Belmont Red herds, grazing predominantly improved pastures growing on cleared brigalow country in the subtropics, were compared over 4 joining seasons. There were a total of 24 Hereford, 23 highgrade Simmental and 26 Belmont Red single sire joining groups. Three Hereford and 7 highgrade Simmental sire groups which had abnormally low pregnancy rates, were removed from the main analyses. The Belmont Red herd had the highest (P<0.05) pregnancy, calving and weaning rates (87, 85 and 81%, respectively). Hereford and highgrade Simmental herds had similar pregnancy (78 v. 75%) and calving (76 v. 73%) rates, but the Hereford herd had higher (P<0.05) weaning rates (68 v. 60%). Reproductive rates were affected by seasonal conditions, being lowest in the 1982-83 joining year which followed drought conditions. Depression in productivity, due to seasonal conditions, was greater in the Hereford and highgrade Simmental herds than in the Belmont Red herd. Pre-natal foetal losses from established pregnancy to the start of calving averaged 2.5% of pregnant cows, with no breed effect. Peri-natal calf losses, from the start of calving to 7 days post calving, were lowest in Belmont Red (2.9%) and higher in highgrade Simmental (1 0.2%) than Hereford (5.8%) (P<0.05). The incidence of assisted births amongst primiparous 3-year-old cows was Hereford 11.9, highgrade Simmental 21.7 and Belmont Red 2.5% (P<0.05) and averaged 0.4% amongst multiparous cows, with no breed effect. Birth weights of calves that died during the pen-natal period were 37.0, 42.5 and 35.0 kg for Hereford, highgrade Simmental and Belmont Red, respectively, and were 2.0 kg higher than those of calves that survived to weaning. Post-natal calf losses were lower (P<0.05) in the Belmont Red (1.7%) than in the Hereford and highgrade Simmental herds (5.1%). Birth weights of calves which died postnatally were 2.1 kg lower than those of calves that survived to weaning. Death rates of primiparous cows were Belmont Red 2.0, Hereford 5.8 and highgrade Simmental 11.8% (P<0.10). Amongst multiparous cows, death rates were Belmont Red 0.9, Hereford 2.2 and highgrade Simmental2.9% (P>0.05).
Lamb and milk production from Booroola ewes supplemented in late pregnancy
Authors: Hall DG , Piper LR , Egan AR , Bindon BM
Published: March 2005

Booroola ewes in moderate body condition on pasture, were either not supplemented, or supplemented prior to parturition with lupin grain for 9 days in a preliminary experiment, or with lupin or oat grain for 17 days in the main experiment. Measurements included lamb birth weight and survival and, in the main experiment only, ewe milk production and lamb immunoglobulin concentrations. With 9 days of lupin grain supplementation, lamb survival to weaning increased by about 12% (P<0.05), size of litter weaned increased from 1.26 to 1.52 (P<0.01) and lamb birth weight increased by about 0.2 kg (P<0.01). In the main experiment, supplementation with lupins resulted in 95% survival to day 9 of twin-born lambs, compared with 68% for lambs from control and oat-fed ewes (P<0.05). Extra lamb losses, due to starvation in the unsupplemented group, were matched by losses due to dystocia in the fed groups. Lamb birth weights, and ewe milk production and composition, were similar across treatments. During the feeding treatment period, only the lupin supplemented ewes maintained their fat score while the other ewes lost 0.5 of a fat score (P<0.01). Fewer (P<0.1) multiple-born lambs from lupin supplemented ewes had low serum immunoglobulin scores, indicating that the lupin supplement may have affected production or intake of colostrum.
Effect of potassium, magnesium and nitrogen supply on grape juice composition of Riesling, Chardonnay and Cabernet Sauvignon vines
Authors: Ruhl EH , Fuda AP , Treeby MT
Published: March 2005

The effect of nitrogen (0 and 60 kg/ha), potassium (0 and 60 kg/ha) and magnesium (0 and 60 kg/ha) supply on grape juice composition was studied in a factorial block design on 3 varieties (Chardonnay, Cabernet Sauvignon and Riesling) grown in the Sunraysia (Karadoc, Nangiloc) (warm, irrigated), Coonawarra (moderately cool) and Mornington Peninsula (Dromana) (cool) districts of Victoria. Increased nitrogen supply appeared to be the most important nutritional factor, significantly increasing grape juice pH and malate concentration in all 3 varieties, citrate in 2 and tartrate and potassium concentrations in 1. Increased potassium supply increased juice pH significantly in only 1 variety, but malate and potassium concentrations in 2. Magnesium was the only fertiliser whose application led, at least in 1 variety, to a significant reduction of grape juice pH. Most treatment effects on grape juice composition were quite small, but nevertheless significant, indicating that particular fertiliser applications could be used as a management tool for the production of quality winegrapes.
Physical management and interpretation of an environmentally controlled composting ecosystem
Authors: Harper E , Miller FC , Macauley BJ
Published: March 2005

Compost for mushroom cultivation was prepared in an environmentally controlled composting(ECC) system of 10 t maximum loading. Early in processing, ventilation was manually controlled to provide aerobic conditions. When the desired compost temperatures were reached, control through temperature feedback was used. Physical uniformity of processing conditions was achieved by recirculating large volumes of air within the reactor. Heat production was found to peak early in the composting process, reaching a maximum of about 8-9 W/kg initial wet (67-71%) substrate. When compost temperatures were allowed to rise to 63�C, maximum heat production occurred at 55-63�C. Total heat production per initial wet weight averaged 1.23 MJ/kg (range 0.92-1.51 MJ/kg), or 5.11 MJ/kg (range 4.04-7.57 MJ/kg) when measured per initial volatile dry matter. Heat evolution averaged 18.3 MJ/kg decomposed (range 15.4-22.0 MJ/kg). Oxygen usage followed a pattern similar to that of heat production reaching a maximum in the 55-63�C range. Peak O2 usage was about 9 x 10-7 kg O2/kg composts, or in volume terms, 2.9 x 10-6 m3 Air/kg comp0st.s. During temperature feedback control, O2 levels were maintained at about 19%. The enclosed ECC system permitted mass balance data to be collected for various components. Trials demonstrated that temperature and O2 could be closely controlled, resulting in-good compost uniformity.
Reduction in the seed reserve of subterranean clover following the application of 2,4-D amine, dicamba, dicamba plus MCPA amine or glyphosate in spring
Authors: Schroder PM , Stapleton PJ
Published: March 2005

The reduction in the net seed set by subterranean clover (mostly cv. Mount Barker), and hence the size of the seed reserve, was assessed at sites near Hamilton, Victoria, following the application of dicamba, 2,4-D amine, a mixture of dicarnba and 2,4-D amine, or glyphosate, applied at early, mid or late flowering. Similar measurements were made on pastures dominated by cv. Yarloop near Seymour, Victoria, where either 2,4-D amine or a mixture of dicamba plus MCPA amine was applied at mid flowering. The experiments were conducted in 1984 and 1985 in both districts. At Hamilton, the clover seed reserve was 147 kg/ha before the treatments were applied. By early summer, the average seed reserve was 511 kg/ha where no herbicide was used and 211, 343 and 318 kg/ha where dicamba, 2,4-D mine or glyphosate were applied. The average reduction in net seed set for these 3 treatments was 80, 46 and 39%, respectively. Applying 2,4-D arnine in addition to dicamba did not cause a further significant reduction in the seed reserve. The earlier in the flowering stage the herbicide was applied, the greater the reduction in net seed set, and so the smaller the final seed reserve. At Seymour, the Yarloop clover seed reserve was 246 kg/ha before the treatments were applied. The average Yarloop seed reserve by early summer was 754 kg/ha where no herbicide was used, 335 kg/ha where dicamba plus MCPA arnine was applied and 365 kg/ha where 2,4-D amine was applied. The average reduction in the net seed set for the 2 herbicides was 83 and 77%. This work indicates that no seed will be added to the seed reserve of Mount Barker or Yarloop subterranean clover if dicamba is applied at 1.0 L/ha before the clover reaches the mid flowering stage. As cultivars differ in their susceptibility to herbicides, extending these results to other cultivars needs to be done with caution.
Influence of nectar volume and sugar content on seed set in lucerne
Authors: Holtkamp RH , Morthorpe KJ , Clift AD
Published: March 2005

Twenty-four cultivars of lucerne, representing the genetic variation currently grown in Australia, were grown with flood irrigation at the Agricultural Research Centre, Trangie, New South Wales. Soil type was a red-brown earth Dr 2.23. Plants were sampled during peak flowering to determine nectar volume per 100 florets. Seed set was determined by hand collection and threshing of 100 racemes of mature pods per cultivar. Glucose, fructose and sucrose concentrations in the nectar were measured using high pressure liquid chromatographic analysis. NO other sugars were found in the nectar. Seed set was found to be correlated (r = 0.74, P<0.01) with both nectar volume and sucrose concentration.
Effect of limited irrigation on growth and yield of a semi-dwarf wheat in southern New South Wales
Authors: Thompson JA , Chase DL
Published: March 2005

The semi-dwarf wheat cv. Egret, was subjected to moisture stress at specific growth stages in a field experiment in the Murmmbidgee Irrigation Area of New South Wales. The 6 treatments ranged from natural rainfall (129 mm of effective rainfall) to flood irrigations in the spring. Moisture stress during spike emergence and anthesis reduced yield from 7.0 to 3.3 t/ha through reductions in spikesJm2 (37%), individual grain weight (15%) and grain number per spike (13%). Stress during grain filling reduced yield by 20% mainly through a 16% reduction in individual grain weight. Irrigation treatment also significantly influenced dry matter production, plant height, leaf area, duration of grain filling and grain protein. Where irrigation water supply is limited, the best strategy would be avoidance of moisture stress during tillering through to spike emergence. An effective rooting depth of 70-80 cm was extended to >110 cm under severe moisture stress during grain filling, but at the expense of considerable yield.
Determination of critical nitrogen concentrations of lettuce (Lactuca sativa L. cv. Montello) grown in sand culture
Authors: Huett DO , White E
Published: March 2005

A gamma x cubic response surface model was used to predict the dry matter yield of lettuce cv. Montello over the 8-week growth period in sand culture with nitrogen (N) levels of 2, 5, 11, 18 and 36 mmol/L. At 1, 2, 3, 5, 7 and 8 weeks after transplanting, dry matter yield relative to maximum was plotted against tissue N concentration to derive diagnostic concentrations of petiole sap nitrate-N and leaf total N in youngest fully opened leaf (YFOL), youngest fully expanded leaf (YFEL) and oldest green leaf (OL), and total N in bulked leaf samples. Critical concentrations corresponding to 90% maximum yield are presented. Growth was consistently depressed at 2 mmol N/L due to N deficiency, and at 36 mmol N/L due to salt toxicity. Petiole sap nitrate concentrations were more responsive than leaf total N concentrations to N application levels. Leaf N concentrations at N application levels of 18 and 36 mmol/L were often similar. Critical leaf total N concentrations in YFOL and YFEL decreased from 2 weeks after transplanting to maturity, whereas the opposite trend occurred for petiole sap nitrate concentrations. Critical total N concentration ranges in YFEL were 0.30-0.95 g/L for petiole sap nitrate-N, and 4.00-5.30% for leaf total N concentration. Critical leaf total N and petiole sap nitrate concentrations clearly differentiated between inadequate and adequate N application rates. Critical values in most cases, differentiated toxic concentrations. Nitrogen application levels of 2 and 36 mmol N/L reduced (P<0.05) potassium, calcium and magnesium concentrations in all leaves. This confirms the importance of optimising N supply when determining critical levels of these nutrients for lettuce. Petiole sap nitrate-N concentrations, which can be determined rapidly in the field, can be used to distinguish between a deficient and an adequate N supply. The marked increase in critical concentration over the growth period requires consecutive determinations to verify the N status of lettuce.
Bleaching ornamental plant material: a brief review
Authors: Dubois P , Joyce DC
Published: March 2005

The Australian dried flower and foliage industry is expanding rapidly because of increasing demand overseas for unique native flora. The industry compliments the export of fresh, native cut flowers. Bleaching is an important step in the processing of plant material that is to be marketed, bleached or dyed. Profitability is dependant upon attainment of high white quality and on cost efficient utilisation of expensive bleaching chemicals. Sodium chlorite is an excellent bleaching agent because it is relatively selective for lignin. Hydrogen peroxide may be more practical for some plant materials because it is less expensive. Choice of an effective bleach activator, such as hypochlorous acid for chlorite bleach, is critical for cost efficient processing. Relative efficiency of different bleach regimes can be compared by assaying residual lignin using ultraviolet or fourier transform infrared spectroscopy. Multistage bleaching, where peroxide is used first to remove about 50% of lignin, followed by chlorite treatment, is likely to reduce processing costs.
Formation and pedology of duplex soils
Authors: Chittleborough DJ
Published: March 2005

The term 'duplex' was first used by Northcote (1960) in his classification 'A Factual Key for the Recognition of Australian Soils' to describe soils which have an abrupt textural contrast between the surface soil horizons and the subsurface. Chemical, mineralogical and physical properties other than the textural contrast are not diagnostic. It is not surprising therefore, that duplex soils exhibit great diversity in their properties, particularly their genesis and mode of development. Many theories-chemical, physical, biological-have been proposed to explain the origin of duplex soils and the processes responsible for the development of their dominant morphological characteristic, the texture contrast. These theories, and some of the implications for an understanding of soil development, are reviewed.
Components of the water balance on duplex soils in Western Australia
Authors: Gregory PJ , Tennant D , Hamblin AP , Eastham J
Published: March 2005

The water balance of soils is of interest both in terms of crop productivity and of sustainability, because water that is not used by crops contributes not only to loss of yield but also to the processes of land degradation. Land clearance for agriculture in Western Australia has changed the hydrological balance resulting in greater drainage and increased secondary salinisation. The relative importance of components of the water balance changes with rainfall. In the drier, eastern wheatbelt, evapotranspiration dominates the balance and there is little drainage, except through narrow, preferred pathways. In contrast, in the wetter region of the Darling Peneplain up to 40% of rainfall may be lost by pathways other than evaporation. Movement of water at the interface of the sand and clay layers (throughflow) has been poorly quantified. The dominant direction of flow is vertical, but substantial lateral flow may occur during winter storms on sloping sites. For example, measurements at a site near Narrogin showed up to 15 mm of throughflow during the cropping season. Drainage using interceptor drains provides a practical means of removing the throughflow and reducing the incidence of waterlogging. Yields of wheat on duplex soils are poorly related to the amount of evapotranspiration. At low rainfall, the relationship is poor, because rainfall is rarely uniformly distributed throughout the season, and lack of water during grain-filling may depress yields. In high rainfall areas, there are few detailed studies of water use, but yields may be lower than anticipated because of waterlogging, low inputs of fertiliser, and disease.
Components of the fertiliser nitrogen balance for wheat production on duplex soils
Authors: Fillery IR , McInnes KJ
Published: March 2005

In this paper, we review literature on the fate of fertiliser nitrogen (N) applied to duplex soils in wheat-growing regions of southern Australia, and discuss the contribution of specific N transformations to N loss. Duplex soils are characterised by the presence of soil material, within the rooting depth of crops, that possess hydraulic conductivities that are lower than those of overlying material. Denitrification and the transport of nitrate below rooting depth of crops are thought to be the chief causes of loss of fertiliser N and to contribute to poor grain yields. Ammonia volatilisation could contribute also to N loss. The fate of fertiliser N commonly applied to wheat in southern Australia has largely been evaluated using budgeting procedures using l5N, a stable isotope of N. Results from studies in south-eastem Australia, using red-brown earths, indicate that between 10 and 40% of applied 15N can be lost irrespective of time of application to wheat. Denitrification is believed to be the chief cause of loss of l5N. Similar studies on yellow duplex soils in Western Australia have shown fertiliser N loss to range from 70% to no loss of the l5N applied. The exact cause of N loss in Western Australian studies is unclear. There was circumstantial evidence for ammonia loss from surface-applied urea, and evidence of leaching of nitrates from this and other ammoniumbased fertilisers. The role of denitrification has not been clarified in Western Australian studies. In the majority of studies, recovery of 15N in aboveground biomass exceeded 40% of that applied. In addition, between 17 and 48% of applied 15N, of which 10-15% may be in root material, has been recovered in the soil organic matter pool. The predominance of the denitrification process in south-eastern Australian soils, and the inability to improve the efficiency of utilisation of 15N by delaying the time of application to wheat underscores the importance of controlling the nitrification process using inhibitors. Management options for Western Australian soils are less clear. Some agronomic experiments have demonstrated the advantage of delaying the application of fertiliser N to wheat to improve the efficiency of its utilisation. There is also evidence which suggests that N should be applied early in the growth cycle to promote tiller development and thereby increase the potential for grain yield.
Limitations to growth and yield of cereal and lupin crops on duplex soils
Authors: Belford RK , Dracup M , Tennant D
Published: March 2005

The combination of soil physical and chemical properties in duplex soils can depress crop growth and yield, and cause considerable variability in yield within a paddock and from year to year. At an intensively monitored site at East Beverley, Western Australia, the sandy A horizon was found to be nutrient deficient, low in pH, and contained hard layers which impeded root growth. The clayey B horizon had a higher pH, and variable permeability which influenced waterlogging in winter, and root growth and water availability from the subsoil in spring. Growth of wheat and lupin crops reflected response to these stresses. Wheat yields in particular were very variable (0.7-4.2 t/ha in 1988), and as all components of yield were affected, this suggests that the crop in low yielding areas experienced stress throughout the growing season. Lupin yields varied more widely from year to year than wheat yields, but were less variable within a year, possibly because of a more limited exploration of the subsoil by roots. Treatments to overcome the chemical constraints to growth raised yields and reduced variability; wheat and lupin yields were increased by about 25% after application of potassium, and wheat yields increased by about 10% after application of lime. Ripping lowered soil strength in the A horizon, but had little effect on yield, suggesting that the subsoil plays a larger role in determining yield on this soil. Attempts to improve the permeability of the subsoil using gypsum were inconclusive in the year of application. Similar physical and chemical problems have been identified on other duplex soils throughout Australia. Responses to ameliorative treatments have been variable, and there have often been interactions between treatments. Further improvements in yield on these difficult soils requires a better understanding of the interaction of soil physical, chemical and biological properties, and their interactions with crop physiology.
Constraints to root growth of wheat and lupin crops in duplex soils
Authors: Dracup M , Belford RK , Gregory PJ
Published: March 2005

Duplex soils constitute about 60% of the cropping region of Western Australia and are usually cropped with wheat or lupins. Extensive and deep root growth is particularly important to crop production on these soils, because the nutrient- and water-holding capacities of the A horizon are frequently low. However, properties of the soils and the Mediterranean-type climate impose several constraints to root growth. Physical and chemical properties of duplex soils are spatially variable, leading to pronounced variation (from metres to tens of metres) in the growth of roots and shoots. Both the A and B horizons often impede root growth mechanically, with bulk density and penetrometer resistance frequently exceeding 1.8 Mg/m3 and 2 MPa, respectively. Also, saturated conductivities of the B horizon are often <0.01 m/day, leading to waterlogging. Topsoil acidity is often a problem in lighttextured A horizons, with pH declining about 0.1 unit each decade in yellow duplex soils near Beverley, Western Australia, where pH is already usually <4.8. Conversely, in the B horizon of red-brown earths and, sometimes, yellow duplex soils, pH >7 restricts growth of roots of Lupinus angustifolius. Major constraints to root growth often occur together (e.g. waterlogging with acidity, salinity, or mechanical impedance), and this exacerbates problems of root growth and necessitates identification and amelioration of the particular combination of constraints to improve root growth. Although L. angustifolius is often grown on duplex soils, its roots are not suited to these soils. Rooting depth is restricted, and unlike wheat roots, those of L. angustifolius are poorly adapted to ramifying through the soil for efficient water and nutrient extraction. Lupinus angustifolius is also particularly sensitive to high pH, salinity, and, probably, waterlogging. Other species of lupin which are more tolerant of high pH (e.g. L. pilosus) and waterlogging (e.g. L. luteus) may be more appropriate on duplex soils.
The role of crop and pasture legumes in rotations on duplex soils
Authors: Ewing MA , Bathgate AD , French RJ , Revell CK
Published: March 2005

Duplex soils are prominent in southern Australia and are generally low in fertility. Their agricultural performance is, therefore, suboptimal in most circumstances without an exogenous source of nitrogen. This is often supplied by legumes which are grown in rotation with non-leguminous crops. Both crop and pasture legumes are now widely used in southern Australia and the contribution that they make to the non-legume phase of rotations is through nitrogen fixation and through other mechanisms such as cereal disease breaks. We use a mathematical programming model, MIDAS (Model of an Integrated Farming Dryland Agricultural System), to investigate the role of legumes in the low rainfall wheatbelt of Western Australia. The impact of legumes on farm profitability is assessed with a special focus on the contribution of legumes grown on a duplex soil. By using the model, the sensitivity of rotation choice on this duplex soil to changes in biological and economic parameters is explored. We conclude that crop legumes, in particular, have a firmly established role on sandy-surfaced duplex soils in low rainfall regions and that substantial increases in both the productivity and legume content of pasture would be required to outperform rotations which include crop legumes.
Warren Reservoir catchment studies: chemistry of throughflow water immediately above sodic B horizons
Authors: Naidu R , Hollingsworth I , Fitzpatrick RW
Published: March 2005

No abstract available.
Mole channel stability in duplex soil
Authors: MacEwan RJ
Published: March 2005

No abstract available.