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1
Norbury, GL, DC Norbury e RB Hacker. "Impact of Red Kangaroos on the Pasture Layer in the Western Australian Arid Zone." Rangeland Journal 15, n. 1 (1993): 12. http://dx.doi.org/10.1071/rj9930012.
Testo completoAbstract (sommario):
We studied the impact of grazing by red kangaroos (Macropus rufus) on pasture biomass and species diversity over a 32-month period in destocked open shrubland in the Gascoyne region of Western Australia. Grazing significantly impeded the accumulation of annual and perennial grass biomass in a degraded perennial shrub community (Pc0.001 and P<0.05) and on denuded sites that were cultivated and reseeded with native shrubs (P<0.01 and Pc0.01). The accumulation of annual and perennial forb biomass was unaffected by kangaroo grazing. After 12 months, pasture species diversity was significantly greater on degraded perennial sites protected from kangaroo grazing (P<0.05). Commercial kangaroo shooting did not alleviate the impact of kangaroo grazing on grass accumulation (P<0.01). Unless more effective methods of kangaroo control are integrated with stock reductions, the recovery of degraded rangeland pastures is likely to be severely limited.
2
Wright, Andr�-Denis G., Andrew J. Williams, Barbara Winder, Claus T. Christophersen, Sharon L. Rodgers e Kellie D. Smith. "Molecular Diversity of Rumen Methanogens from Sheep in Western Australia". Applied and Environmental Microbiology 70, n. 3 (marzo 2004): 1263–70. http://dx.doi.org/10.1128/aem.70.3.1263-1270.2004.
Testo completoAbstract (sommario):
ABSTRACT The molecular diversity of rumen methanogens in sheep in Australia was investigated by using individual 16S rRNA gene libraries prepared from the rumen contents obtained from six merino sheep grazing pasture (326 clones), six sheep fed an oaten hay-based diet (275 clones), and five sheep fed a lucerne hay-based diet (132 clones). A total of 733 clones were examined, and the analysis revealed 65 phylotypes whose sequences (1,260 bp) were similar to those of cultivated methanogens belonging to the order Methanobacteriales. Pasture-grazed sheep had more methanogen diversity than sheep fed either the oaten hay or lucerne hay diet. Methanobrevibacter strains SM9, M6, and NT7 accounted for over 90% of the total number of clones identified. M6 was more prevalent in grazing sheep, and SM9, despite being found in 16 of the 17 sheep, was more prevalent in sheep fed the lucerne-based diet. Five new species were identified. Two of these species exhibited very little sequence similarity to any cultivated methanogens and were found eight times in two of the six sheep that were grazing pasture. These unique sequences appear to represent a novel group of rumen archaea that are atypical for the rumen environment.
3
Wheeler, SH, e DR King. "The European Rabbit in South- Western Australia II. Reproduction". Wildlife Research 12, n. 2 (1985): 197. http://dx.doi.org/10.1071/wr9850197.
Testo completoAbstract (sommario):
'The reproduction of the European rabbit, Oryctolagus cuniculus (L.), at two intensive study sites in south-western Australia is compared with reproductive data from rabbits taken throughout the coastal and inland districts of the south-west region. South-western Australia has hot, arid summers and cool wet winters. Rabbit breeding in the region is characteristic of that in Mediterranean climates, with a winter breeding season which begins when pastures germinate with the initial winter rainfall (April-May) and ceases when the pastures dry out at the end of the year. Unseasonal cyclonic rain can promote pasture growth in summer, leading to limited breeding. At all times of year there were some fertile males, with fewest at the height of summer, followed by an increase before the winter breeding season. Near the coast, male fertility increased more rapidly than further inland. At our two study sites at Cape Naturaliste (on the coast) and Chidlow (55 km inland) the pattern was similar to that in the coastal district. Production of kittens was greater near the coast than further inland, because near the coast there was a high early peak in incidence of pregnancy, a second peak late in the year, and litters remained large throughout the breeding season. In the inland district, the early incidence of pregnancy was lower, there was no second peak, and litter sizes fell at the end of the year. Female reproduction at Cape Naturaliste was typical of that in the coastal district, but that at Chidlow was typical of the inland. The second peak of pregnancy at Cape Naturaliste was due to intensive breeding by subadults born earlier in the year. The differences in female reproduction and productivity between the coastal and inland districts are probably because pasture growth begins earlier and is better in the more fertile coastal areas than in the inland. That nutrition is better for rabbits in the coastal areas than in the inland is reflected in higher growth rates of kittens at Cape Naturaliste than at Chidlow. It is postulated, on the basis of the literature and the results of our studies, that the factor which determines whether rabbits will breed is the presence of growing vegetation, and that the intensity of breeding is influenced by a seasonal cycle in fertility.
4
Holm, AM, e RJ Allen. "Seasonal changes in the nutritive value of grass species in Spinifex pastures of Western Australia." Rangeland Journal 10, n. 1 (1988): 60. http://dx.doi.org/10.1071/rj9880060.
Testo completoAbstract (sommario):
This study was undertaken to assess whether the nutritional quality of spinifex pasture lands is improved by buming to promote the growth of grasses other than spinifex. We selected two comparable sites in the Exmouth Gulf region of Western Australia; one had been bumt in late 1979 and the other had not been burnt for many years. On these sites we sampled the five grass species present, as well as Triodia pungens (soft spinifex) and Plectrachne >chinzii (Oat eared spinifex) on 10 occasions from March 1980 to April 1982. Plant parts were analysed for nitrogen, phosphorus and sulphur content, and in vitro digestibility. None of the common grass species tested was more nutritious or more palatable than soft spinifex. It seems that little is gained from manipulating spinifex pastures through burning if the aim is to encourage alternative grass species. There is a need however for further studies into the importance of woody herbs and forbs in the nutrition of grazing animals on spinifex country and the effect of fire on these species.
5
Twigg, Laurie E., Tim J. Lowe, Gary R. Martin, Amanda G. Wheeler, Garry S. Gray, Sandra L. Griffin, Catherine M. O'Reilly, Tania L. Butler, David J. Robinson e Peter H. Hubach. "The ecology of the European rabbit (Oryctolagus cuniculus) in coastal southern Western Australia". Wildlife Research 25, n. 2 (1998): 97. http://dx.doi.org/10.1071/wr97066.
Testo completoAbstract (sommario):
Demographic changes in three free-ranging rabbit (Oryctolagus cuniculus) populations were monitored over 4 years in southern Western Australia. Peak densities followed periods of high rainfall and pasture biomass. The breeding season was prolonged, often extending from at least April to November, with some pregnancies occurring outside this period. Fecundity, determined by the autopsy of pregnant offsite rabbits and the known length of each breeding season, appeared to be relatively high, with the potential for 34–39 kittens doe-1 year-1; however, because not all females are pregnant in all months, the overall productivity of these populations was estimated at 25–30 kittens adult female-1 year-1. Exponential rates of increase varied from 0.13 to 0.30 during the breeding periods and –0.05 to –0.14 during the nonbreeding season. Kitten survival was generally low whereas some adults lived for more than 5 years. Two patterns of myxomatosis were observed: annual epizootics of the disease (3 of 4 years) and an epidemic that slowly spread over many months. European rabbit fleas were most abundant during winter–spring and attained highest densities on adult female rabbits.
6
Southcott, RV. "Larvae of Leptus (Acarina : Erythraeidae) ectoparasitic on higher insects of Australia and New Guinea". Invertebrate Systematics 7, n. 6 (1993): 1473. http://dx.doi.org/10.1071/it9931473.
Testo completoAbstract (sommario):
Larval Leptus (Acarina : Erythraeidae) ectoparasitic on higher insects (Neuroptera. Coleoptera. Lepidoptera. Hymenoptera) are comprehensively reviewed (Diptera were considered previously) . The new species (all from Australia) comprise: L. spinalatus (from Neuroptera); L. belicolus. L. cerambycius. L. faini. L. halli. L. heleus. L. jenseni. L. orthrius. L. tarranus. L. titinius. L. truncatus. L. utheri (all from Coleoptera); L. agrotis, L. georgeae (from Lepidoptera); and L. monteithi (from Hymenoptera). A key is given to the larvae of Leptus from Australia and New Guinea . L. agrotis is an ectoparasite of Agrotis infusa (Boisduval), the bogong moth, whose larvae are an important pasture pest in south-eastern Australia; as well as the larva, the deutonymph and adult are described. Leptus boggohoranus Haitlinger is recorded from a further New Guinea species of Coleoptera. L. charon Southcott, originally described from an Australian dipteran, is recorded as ectoparasitic on an Australian larval lepidopteran (Anthela sp., Anthelidae), as well as from adult Lepidoptera and Coleoptera. Leptus trucidatus (Hull, 1923), comb. nov., is proposed for Achorolophus trucidatus Hull, 1923, an adult from Western Australia.
7
Hacker, RB, e SB Tunbridge. "Grazing Management Strategies for Reseeded Rangelands in the East Kimberley Region of Western Australia." Rangeland Journal 13, n. 1 (1991): 14. http://dx.doi.org/10.1071/rj9910014.
Testo completoAbstract (sommario):
Grazing management strategies involving continuous grazing, wet season rest, dry season rest and a range of stocking rates of steers were evaluated on reseeded rangeland at Ord Regeneration Research Station by the use of temporary exclosures within continuously grazed paddocks. The rangeland is a patchwork of plant communities in various stages of regeneration. Under continuous grazing, liveweight gain in three of the four years of the trial was more closely related to botanical differences between paddocks than to stocking rate although all paddocks were confined to the one land unit. Animals generally selected those parts of the pasture where regeneration of perennial grasses was least advanced and the vegetation was characterized by short annual and semi-perennial species. Differences in the yield of these species between paddocks accounted for much of the variation in liveweight gain. Perennial species contributed most to animal production when seasonal conditions were poor. Over the study as a whole, year-in-year-out stocking rate was much more important than management system (proportion of wet season grazing) in determining vegetation changes. Nevertheless, selective grazing of the short grass patches will prevent the use of a continuous grazing strategy in these pastures. However, continued regeneration should be feasible under a tactical management system in which grazing is managed to ensure that a minimum level of cover is maintained on the short grass phase and that the end of dry season utilization level for the key perennial species does not exceed an average (over years) of about 30 per cent.
8
James, T. K., e A. Rahman. "Management and control options for tutsan (Hypericum androsaemum) in hill country pastures a review". New Zealand Plant Protection 68 (8 gennaio 2015): 124–31. http://dx.doi.org/10.30843/nzpp.2015.68.5880.
Testo completoAbstract (sommario):
Tutsan (Hypericum androsaemum) is a highly invasive semievergreen shrubby weed found throughout New Zealand Described as a serious pasture weed in 1937 it has been held in check for many years by tutsan rust Recently it has spread rapidly into pasture forestry and conservation areas Present methods available for managing tutsan are proving inadequate and unsustainable This review paper provides an overview of tutsans biology ecology habitat and its current distribution in New Zealand It details possible management strategies and control options with emphasis on control by herbicides The paper identifies a number of potential herbicides which although not currently registered for control of tutsan have shown good efficacy on this weed and could be developed for use on agricultural land through further research Herbicides currently registered for control of tutsan in Australia as well as the current recommendations in Victoria and Western Australia are also summarised
9
Norton, M. R., M. L. Mitchell, E. Kobelt e E. Hall. "Evaluation of native and introduced grasses for low-input pastures in temperate Australia: experimental approach, site and genotype descriptions". Rangeland Journal 27, n. 1 (2005): 11. http://dx.doi.org/10.1071/rj05002.
Testo completoAbstract (sommario):
This paper describes the experimental methodology, sites, seasonal conditions and germplasm used in the Australian Native and Low Input Grass Network (NLIGN). In 1998, eight sites were established across the temperate pastoral zone of southern Australia. These were located at Armidale, Binya, Sutton and Trangie in NSW; Springhurst in Victoria; Jericho in Tasmania; Flaxley in South Australie and Kendenup in Western Australia. A total of 62 lines were evaluated, of which, 29 were Australian native grasses and 33 were introduced. With differences in seed size among species and a lack of information on dormancy and germination characteristics of the native plants, seedlings were transplanted into the field on weed-mat as spaced plants. Lines were compared over a 3-year period from 1998 to 2001. Methods used for determination of forage production, persistence and palatability are described. Information detailing the original collection sites of the germplasm, a list of NLIGN sites where each genotype was evaluated, as well as a detailed description of sites and seasonal conditions is also presented.
10
Martin, Gary R., Laurie E. Twigg e Lina Zampichelli. "Seasonal changes in the diet of the European rabbit (Oryctolagus cuniculus) from three different Mediterranean habitats in south-western Australia". Wildlife Research 34, n. 1 (2007): 25. http://dx.doi.org/10.1071/wr06044.
Testo completoAbstract (sommario):
Abstract.�Seasonal changes in the diet of rabbits from three temperate (Mediterranean) areas in south-western Australia were identified using microscopic determination of the percentage occurrence of various food groups in sampled stomachs. The sites differed in soil type and in the availability of summer perennials, native vegetation bush remnants (size of, and number of plant species), improved pastures, and summer rainfall, and hence, enabled a comparison of the diet of rabbits from the different vegetation communities. Although the diet of these rabbits was quite flexible, with some switching in food items occurring between seasons, there were marked differences in the proportion of monocotyledonous and dicotyledonous species eaten in each habitat. There was a strong reliance on seeds (1-5 species) during late spring and summer in all three habitats. Guildford grass (Romulea rosea) leaf and corms were a major component of the diet in the two habitats where this species was common. Further, as a result of the summer die-off of pasture species, there was a shift in where rabbits sourced food items during winter and summer. Pasture species were eaten during winter, but rabbits fed mainly on those dicotyledons found only in the surrounding scrub during summer. This suggests that rabbits may impact negatively upon such remnant vegetation at this time. Rabbits in all three habitats consumed several plant species with high water content (>54%) during summer, presumably to help maintain their water balance. Rabbits also consumed the seeds and foliage of several weed/nuisance species in each habitat, but any role of rabbits in weed dispersal was not determined.
11
Holm, AM, DG Burnside e AA Mitchell. "The development of a system for monitoring trend in range condition in the arid shrublands of Western Australia." Rangeland Journal 9, n. 1 (1987): 14. http://dx.doi.org/10.1071/rj9870014.
Testo completoAbstract (sommario):
The role of a monitoring system for Western Australian pastoral shrublands is examined. The authors argue that the objective of management is to maximise sustained animal productivity, and that this can only be attained if the soil is maintained in a stable state. In non-degraded rangelands this objective is synonomous with the maintenance of a pasture community with its natural balance of edible and less edible species. In degraded rangelands the objective of regaining the pristine vegetation may, in many cases, be unattainable. Nevertheless, the objective of maximum sustained productivity again appears suitable since this would ensure that, where management is able to influence the direction of change, it is towards a pasture dominated by useful, rather than non-palatable, species. Our monitoring system aims to assist management achieve these objectives. The Western Australian Rangeland Monitoring System (WARMS) has been designed to include the assessment of ecological processes but with a strong bias towards characteristics that can be interpreted in production terms. We expect that the system will primarily and most importantly, aid pastoralists in their season by season decisions on stock movements. It will also provide a tool for the land administrator, who must be able to assure the wider community that the land is being used wisely. Finally, it should assist range scientists towards a better understanding of rangeland ecosystems. The WARMS system involves a series of grazed range monitoring sites, lightly grazed reference areas and ungrazed control areas. At each monitoring site a photograph is taken and plants within a fixed area are identified and marked on an overlay. The number and size of perennial shrubs are recorded within fixed belt transects and the contribution from perennial grasses and biennial species is assessed. Soil stability is also assessed using a rating scale and a modified step point procedure.
12
Fensham, RJ. "Native Grasslands of the Central Highlands, Queensland, Australia. Floristics, Regional Context and Conservation." Rangeland Journal 21, n. 1 (1999): 82. http://dx.doi.org/10.1071/rj9990082.
Testo completoAbstract (sommario):
A floristic classification of grassland and related woodland vegetation from the Central Highlands of Queensland suggests four broad types: Mountain coolibah (Eucalyptus orgadophila) woodland on basalt, Mitchell grassland (dominated by Astrebla lappacea) on alluvia and two closely related groups dominated by Dichanthium sericeum, Blue grassland on basalt and Blue grassland on sediment. An analysis including floristic data from grassland and woodland on vertosols from throughout southern, central and western Queensland revealed that the Blue grasslands of the Central Highlands are highly dissimilar from other grasslands in Queensland. Mountain coolibah woodland on basalt is represented within four reserves, but the other more arable grassland types are either not represented or only barely represented within the reserve system. The most immediate threatening process to these communities is conversion to crops and this process is exacerbated by the difficulties of managing the grasslands as native pasture. Large areas of grasslands are degraded, having been converted from dominance by native perennial grasses to the unpalatable, annual, exotic herb Partheniunz hysterophorus. Once this shift has occurred a long period with little or no production benefits is required to recover a sward of native perennial grasses and the cropping alternative becomes particularly favourable. The long-term security of the native grasslands of the Central Highlands will require an enhanced reserve system and incentives designed to retain appropriately managed native pasture. Key words: grassland, grazing, reserves, woodland. Queensland, exotics, Parthenium
13
Robley, Alan J., Jeff Short e Stuart Bradley. "Do European rabbits (Oryctolagus cuniculus) influence the population ecology of the burrowing bettong (Bettongia lesueur)?" Wildlife Research 29, n. 5 (2002): 423. http://dx.doi.org/10.1071/wr01007.
Testo completoAbstract (sommario):
The influence of the European rabbit (Oryctolagus cuniculus) on the survival of medium-sized native mammals remains unclear despite 60 years of speculation. Most medium-sized native species that might have been affected by the presence of rabbits are extinct, rare, or endangered. This limits the opportunity to study their interaction with introduced herbivores. We studied the effect of changes in rabbit density on aspects of the ecology of burrowing bettongs (Bettongia lesueur) reintroduced to mainland Australia on Heirisson Prong, Shark Bay, Western Australia. The rabbit population at the site grew to a 10-year high concomitant with a dry summer and low and declining pasture cover. Rabbit browsing led to widespread defoliation of, and subsequent death of, many palatable shrubs. Despite these adverse conditions, reproduction, recruitment and rate of increase of bettongs did not vary with changes in rabbit density, nor did the survival of adult males and females. This work casts doubt on the idea that competition with an introduced herbivore, such as the rabbit, was an important factor in the decline of the burrowing bettong. It highlights the need to understand the ecologies and life histories of native and introduced species in order to manage for the long-term persistence of native species.
14
Cocks, P. S. "Ecology of herbaceous perennial legumes: a review of characteristics that may provide management options for the control of salinity and waterlogging in dryland cropping systems". Australian Journal of Agricultural Research 52, n. 2 (2001): 137. http://dx.doi.org/10.1071/ar99170.
Testo completoAbstract (sommario):
Salinity is a widespread problem caused by an imbalance between rainfall and transpiration in the dryland cropping systems of southern Australia. The need to use more perennials has been identified and this paper examines the possibility of replacing annual with perennial pasture legumes and the germplasm available to do so. While lucerne is already used widely in eastern Australia it has only recently been adopted in the wheat belt of Western Australia. There are doubts about its adaptation to acid soils and to climates where summer rainfall is low and ambient temperatures are high. There is also a need to diversify the species available to reduce the likelihood of invasion by exotic diseases and insects. Several genera are likely to be of value in this respect, although few will be as widely adapted as lucerne. Perennial legumes are found in environments ranging from alpine to desert. Targeted collections of genera from the dry areas, especially where soils are acid, are likely to yield species of value. These may include perennial species of Astragalus, Hedysarum, Lotus, Onobrychis, Psoralea, and Trifolium. Some Australian genera, for example Swainsona, Glycine, and Cullen may also be of value. Most of these genera are from alkaline soils, and the need to cope with acid soils that are often high in free aluminium is seen to limit their use in southern Australia. However, since virtually nothing is known of the ecology and ecophysiology of species from the dry areas, it is possible that through selection and the use of adapted rhizobia, some at least may be of value in Australian conditions. Cropping in rotation with perennial legumes is likely to involve several changes in farming systems. It is impossible to predict their nature but it is essential that we understand what these changes are before the species are widely introduced. Account must also be taken of their ability to use water. It is entirely possible that perennials from dry areas are dormant in summer despite the fact that there is no evidence in the literature to this effect. It was concluded that although lucerne is suitable for phase farming, alternatives to lucerne are needed. They will have to match the water-using and nitrogen-fixing capacities of lucerne, and farming systems will be required that make full use of the new germplasm. Collaboration with institutions in the Mediterranean basin and elsewhere is needed and a beginning has been made in this direction.
15
Ryan, WJ, D. Pratchett e BL McIntyre. "Alternative turnoff strategies for Kimberley beef cattle. 1. Live animal performance and carcass characteristics." Rangeland Journal 9, n. 2 (1987): 61. http://dx.doi.org/10.1071/rj9870061.
Testo completoAbstract (sommario):
In June 1980, 190 Kimberley Shorthorn steers from five properties in the Kimberley were divided into three age categories. Half were sent to Chapman Research Station (CRS) in the agricultural area of Western Australia and the remainder stayed at Ord Regeneration Research Station (ORRS) in the Kimberley. Animals in both locations grazed for either one or two pasture growing seasons and a third group was fed a concentrate ration based on grain after the first growing season. Cattle lost between 20-30 kg in handling and transport south which, together with the reduced initial grazing season, led to gains of only 50 kg while those in the north gained around 100 kg. In the second grazing season at both locations animals gained around 140 kg. Animals at ORRS laid down more fat than those at CRS. Animals fed on concentrate rations in the agricultural area grew significantly faster, but had poorer food conversion and were leaner compared with those fed in the Kimberley.
16
McHenry, Melinda T., Brian R. Wilson, Peter V. Lockwood, Christopher N. Guppy, Brian M. Sindel, Matthew K. Tighe, Ivor O. Growns e John M. Lemon. "The impact of individual Callitris glaucophylla (white cypress pine) trees on agricultural soils and pastures of the north-western slopes of NSW, Australia". Rangeland Journal 31, n. 3 (2009): 321. http://dx.doi.org/10.1071/rj08052.
Testo completoAbstract (sommario):
Woody vegetation thickening occurs in agri-ecosystems worldwide, often with negative consequences for production. Dense Callitris glaucophylla (Joy Thomps. & L.A.S. Johnson) stands affect landscapes across NW NSW, Australia, and strategies to reduce tree density to levels which maintain biodiversity values alongside agricultural production are currently being sought. We investigated soil chemical and groundcover patterns associated with individual small and large C. glaucophylla trees at six sites of variable management history and lithology in NW NSW, Australia. We posed two questions: (1) do individual C. glaucophylla trees impose patterns on soil and groundcover (soil extractable P, C, N, S and pH, litter biomass, litter P and pasture cover), and, (2) if patterns exist, do they differ between tree sizes? Results showed that extractable P, C and pH decreased away from trees of both sizes, but significantly higher values were recorded adjacent to the stem of large trees. Litter biomass exhibited a strong site-related trend independent of soil variables. Positive correlations between litter and soil variables existed for some sites and not others, indicative of processes such as grazing which contribute to the transport of litter away from the tree. Irrespective of tree size ground-storey vegetation cover increased significantly away from the stem, presumably as a consequence of competition for soil water. Further results indicated that single C. glaucophylla trees enrich soils in patterns analogous to other species in similar environments worldwide. However, localised soil improvements must be weighed up against the negative effects of decreased groundcover associated with trees, and the potential for the species to re-seed prolifically into managed paddocks. Future research will discern the impact of individual C. glaucophylla trees at higher densities, where soil patterning may be modified by intense within-stand competition.
17
Zahran, BB, AM Holm, WR Stern e WA Loneragan. "The cage method of sampling to assess herbage mass and herbage consumed on annual rangeland vegetation". Rangeland Journal 10, n. 1 (1988): 6. http://dx.doi.org/10.1071/rj9880006.
Testo completoAbstract (sommario):
The cage method of sampling vegetation was used to estimate herbage mass and herbage consumed by sheep, grazing a pasture dominated by annual species, near Camawon, Western Australia. Using paired quadrats (2m x lm), one caged and the other open, herbage mass and herbage consumed were measured at five stocking rates on two soil types, on eight occasions between December 1983 and January 1985. The data were highly variable; nevertheless, some effects of season, soil type and stocking rate could be observed. The results showed clear seasonal trends. Some soil type x stocking rate interactions were detected during the dry periods of the year when herbage mass was low. Generally, the cage method tended to over-estimate herbage consuped. Sheep consumed approximately 119 to 116 of the available herbage at low and high stocking rates respectively when feed was plentiful; when feed was in short supply the corresponding figures were approximately 113 and 1/2. The limitations of the method are discussed and some suggestions made concerning its applicability in rangeland studies.
18
MacLeod, N. D., D. E. Mayberry, C. Revell, L. W. Bell e D. B. Prestwidge. "An exploratory analysis of the scope for dispersed small-scale irrigation developments to enhance the productivity of northern beef cattle enterprises". Rangeland Journal 40, n. 4 (2018): 381. http://dx.doi.org/10.1071/rj18026.
Testo completoAbstract (sommario):
The major economic use of the northern Australian rangelands is beef cattle grazing. Beef production enterprises are typically large and employ ‘low-input’ herd and pasture management systems, and the longer-term viability and sustainability of many is uncertain. Productivity gains have been stagnant for most of the past decade, and nutritional constraints are a major source of the poor animal production and financial returns across the sector. There has been a growing interest in the scope for small-scale, dispersed irrigation developments – mosaic irrigation – to provide an augmented supply of higher-quality forages to certain classes of animals in order to alter their reproduction and/or growth potential and to exploit market opportunities. An ex-ante economic review undertaken by the CSIRO of the prospects for mosaic irrigation employed bioeconomic simulation modelling of case studies of irrigation development scenarios conducted at the individual beef enterprise scale in three contrasting regions of northern Australia – the Burdekin (north Queensland), the Barkly Tableland (Northern Territory) and the Kimberley (northern Western Australia). This paper presents a summary of the methods, results and conclusions of the case study modelling. The results present a mixed picture of the economic potential for the various irrigation development options that were canvassed. The level of animal productivity (e.g. average weight of sale animals) increased for all of the irrigation simulation scenarios, but in most instances the projected economic advantage ranged from negative to only moderately positive across the three regional case studies. Where there was an apparently attractive return on the irrigation investment (e.g. a real internal rate of return of >15%), this primarily occurred under the more buoyant market conditions that have prevailed in recent years. The influence of irrigated forage availability on herd structure through management options such as the early weaning of calves appears to be at least as valuable as changes in liveweight gain for particular classes of animals.
19
Garden, D. L., C. M. Waters, A. B. Smith, M. R. Norton, G. C. Auricht e E. Kobelt. "Performance of native and introduced grasses for low-input pastures. 2. Herbage production". Rangeland Journal 27, n. 1 (2005): 41. http://dx.doi.org/10.1071/rj05003.
Testo completoAbstract (sommario):
A total of 62 perennial grasses were evaluated for herbage production under low-fertiliser conditions at eight sites in the temperate zone of southern Australia from 1999 to 2001. A brief assessment of relative preference ranking by sheep was also made at the end of the experimental period. Four sites were in the high rainfall areas of south-east Australia, two in the drier mixed farming areas of western NSW, and two sites in Mediterranean southern Australia. Seven standard cultivars were included in the comparisons. Plants were grown from seed in glasshouses and transplanted to the field as spaced plants at 6–8 weeks age. Plants were harvested at irregular intervals by clipping to determine herbage production. Relative preference was determined by enclosing sheep in the experimental area at high stocking rates and estimating the amount of herbage grazed after 1, 3 and 5 days. Herbage production data were analysed using a multi-environment trial approach in which the environments comprised all combinations of sites and sampling times over the 3-year period. Overall, 73.6% of the total genetic variation for herbage production was accounted for. Average seasonal comparisons revealed good herbage production from Eragrostis curvula cv. Consol in both winter and summer, but in spring, several Dactylis glomerata lines were the most productive. Consol was not generally preferred by sheep, while D. glomerata lines were. Apart from cv. Consol, C4 species, including Bothriochloa macra, Chloris truncata, Enteropogon acicularis and Dichanthium sericeum had low herbage production in winter and spring, and had low acceptability to grazing sheep. These particular grasses were also not highly ranked for production in summer, although other C4 lines, notably selections of Themeda australis, Paspalidium jubiflorum and P. constrictum were. Few native C3 grasses had superior herbage production, although selections of Elymus scaber, Austrodanthonia fulva and A. duttoniana showed good growth rates. When considering further evaluation, grasses with very high recruitment (e.g. A. caespitosa) may need to be included, and the acceptability of grasses to sheep should also be assessed.
20
Newsome, A. E., P. C. Catling, B. D. Cooke e R. Smyth. "Two ecological universes separated by the Dingo Barrier Fence in semi-arid Australia: interactions between landscapes, herbivory and carnivory, with and without dingoes". Rangeland Journal 23, n. 1 (2001): 71. http://dx.doi.org/10.1071/rj01015.
Testo completoAbstract (sommario):
This paper challenges conclusions of Caughley et al. (1980) that the abundance of red kangaroos (Macropus rufus) in western New South Wales is solely due to lack of dingoes (Canis lupus dingo), and vice versa for neighbouring South Australia. A Dingo Barrier Fence divides the two different ecological systems, which have sheep in New South Wales and cattle in South Australia. This paper re-examines in particular whether there is an environmental gradient across the Fence that was dismissed by Caughley et al. This paper concludes to the contrary, that there is a strong environmental gradient. Our aerial surveys demonstrate significantly that habitats favouring red kangaroos are prevalent in New South Wales today, but are very scarce or absent in South Australian landscapes. Aerial surveys were used in both studies, but designs differed. Caughley et al. flew at right angles across the Fence on paths 28 km apart. Flights would have crossed the south-westerly streamlines rarely. Our flight lanes followed streamlines looking for floodouts, the favourite habitat of red kangaroos. Return lanes went between streamlines sampling other habitats. Counts of red kangaroos seen were made every 1.75 km, with the specific habitat also identified. Three extra factors are invoked in our study. One is that the low annual rainfalls translate into intrinsically low survival rates of pouch-young of red kangaroos, contrary to their abundance in New South Wales today. The other two are related to that current abundance also. There is now evidence for greatly increased run-off of rainfall from catchments onto the open plains in New South Wales. Also present is a very large shallow basin lying between catchments and the Dingo Barrier Fence. Streamlines enter it but none flow past its western rim. The above conclusions were confirmed during subsequent ground surveys over three years. Of eleven species of medium and large vertebrates seen in New South Wales, five were absent in South Australia. Three were kangaroos, and the others were feral pigs and goats. Emus are more abundant in New South Wales also. All of those species would be targets for dingoes, especially as alternate prey to rabbits that generate huge eruptions every decade or so. Red foxes (Vulpes vulpes) were in lower abundance in South Australia with dingoes present, as expected with meso-predator interactions. Feral cats (Felis catus) were in similar numbers on both sides of the Fence for unknown reasons. Competition between rabbits (Oryctolagus cuniculus) and sheep for food in New South Wales was shown to significantly reduce rabbit numbers in drought. That rabbits are perennially in lower densities there than in South Australia may be due to the higher densities of foxes than in South Australia. Historically, red kangaroos were rare in the region in the mid-1800s. Their abundance has arisen since European occupation. Thc species was rare on those open plains, and permanent water was scarce. Rabbit Haemorrhagic Disease reached the study-area in 1995. Its impact reduced rabbit populations to a rarity that prevails today on both sides of the Dingo Fence. Predation from dingoes, foxes and feral cats may assist continuance of low numbers of rabbits. Pastures, seedling trees and livestock will benefit, as will the kangaroos.
21
HALLIDAY, R. B. "Predatory mites from crops and pastures in South Africa: potential natural enemies of redlegged earth mite Halotydeus destructor (Acari: Penthaleidae)". Zootaxa 1079, n. 1 (11 novembre 2005): 11. http://dx.doi.org/10.11646/zootaxa.1079.1.2.
Testo completoAbstract (sommario):
A survey was conducted in crops and pastures in the Western Cape Province of South Africa, in a search for predatory mites that could have potential for introduction into Australia as biological control agents of redlegged earth mite Halotydeus destructor (Penthaleidae). A total of over 1200 specimens was examined, and 56 species of predatory mites belonging to 14 families were found. Information is presented for 33 known species, including synonymy and bibliography, geographic distribution, and biology where known. Eight species in six families are described as new¨®Bdellodes edentata sp. nov. (Bdellidae), Hypoaspis calcarata sp. nov. (Laelapidae), Hypoaspis muellerae sp. nov. (Laelapidae), Macrocheles propinquus sp. nov. (Macrochelidae), Gamasiphoides lootsi sp. nov. (Ologamasidae), Gamasiphoides rykei sp. nov. (Ologamasidae), Pachylaelaps meganalis sp. nov. (Pachylaelapidae), and Rhagidia meyerae sp. nov. (Rhagidiidae). Fifteen species could not be fully identified because suitable specimens were not available. Of the 41 species that could be identified, nine are already present in Australia. A further 20 species are not known from Australia, but were rare in South Africa and therefore unlikely to be useful predators. Twelve species occurred in significant numbers in South Africa and are not known from Australia. Most of these are known or believed to be generalist predators, and are therefore unlikely to be approved for introduction into Australia. Chaussieria capensis (Anystidae) was considered to have potential and has been studied further. The survey did not identify any other species that were considered to be suitable as biological control agents.
22
Bennett, R. G., M. H. Ryan, T. D. Colmer e D. Real. "Prioritisation of novel pasture species for use in water-limited agriculture: a case study of Cullen in the Western Australian wheatbelt". Genetic Resources and Crop Evolution 58, n. 1 (12 maggio 2010): 83–100. http://dx.doi.org/10.1007/s10722-010-9567-3.
Testo completo
23
S. Watkins, R. ""Payneham Vale": integrated whole farm Planning". Pacific Conservation Biology 9, n. 1 (2003): 65. http://dx.doi.org/10.1071/pc030065.
Testo completoAbstract (sommario):
IN 1908, Ron's grandfather, Issac Gray, took up an uncleared block of land 15 km north of Frankland in the south-west of Western Australia (see Fig. 1, Hobbs 2003). During that time he ran a few cattle in the bush and clearing of the native woodlands of Wandoo (white gum) Eucalyptus wandoo, J arrah E. marginata and Marri (Redgum) E. calophylla was slow and tedious. Ron's parents took over the farm in 1947, and with the advent of the bulldozer, clearing of Watkin's property and surrounding district began in earnest during the 1950s. Clearing continued as fast "as money permitted", until almost the last natural vegetation was knocked down in 1978 (Fig. 1). Annual pastures with some cropping (for supplementary feed) were the main source of fodder for sheep and cattle.
24
Craig, AB. "Fire Management of Rangelands in the Kimberley Low-Rainfall Zone: a Review." Rangeland Journal 21, n. 1 (1999): 39. http://dx.doi.org/10.1071/rj9990039.
Testo completoAbstract (sommario):
This paper examines a range of environmental, research and practical issues affecting fire management of pastoral lands in the southern part of the Kimberley region in Western Australia. Although spinifex grasslands dominate most leases, smaller areas of more productive pastures are crucially important to many enterprises. There is a lack of local documentation of burning practices during traditional Aboriginal occupation; general features of the fire regime at that time can be suggested on the basis of information from other inland areas. Definition of current tire regimes is improving through interpretation of NOAA-AVHRR satellite imagery. Irregular extensive wildfires appear to dominate, although this should be confirmed by further accumulation, validation and analysis of fire history data. While these fires cause ma,jor difficulties. controlled burn~ng is a necessary part of station management. Although general management guidelines have been published. local research into tire-grazing effects has been very limited. For spinifex pastures, reconimendations are generally consistent with those applying elsewhere in northern Australia. They favour periodic burning of mature spinifex late in the year, before or shortly after the arrival of the first rains, with deferment of grazing. At that time. days of high fire danger may still be expected and prediction of fire behaviour is critical to burning decisions. Early dry-season burning is also required for creating protective tire breaks and to prepare for burning later in the year. Further development of tools for predicting fire behaviour, suited to the discontinuous fuels characteristic of the area, would be warranted. A range of questions concerning the timing and spatial pattern of burning, control of post-fire grazing, and the economics of fire management, should be addressed as resources permit. This can be done through a combination of opportunistic studies, modelling and documentation of local experience. The development of an expert system should be considered to assist in planning and conducting burning activities. Key words: Kimberley, fire regimes, fire management, pastoralism, spinifex
25
Oram, Rex, e Greg Lodge. "Trends in temperate Australian grass breeding and selection". Australian Journal of Agricultural Research 54, n. 3 (2003): 211. http://dx.doi.org/10.1071/ar02137.
Testo completoAbstract (sommario):
Current trends in grass cultivar development are reviewed, with respect to the range of species involved, and the objectives and methodology within each species. Extrapolations and predictions are made about future directions and methodologies. It is assumed that selection will necessarily cater for the following environmental changes: (1) higher year-round temperatures, higher variability of rainfall incidence, and lower total winter and spring rainfall along the south of the continent; (2) higher nutrient and lime inputs as land utilisation intensifies; and (3) the grazing management requirements of the important pasture components will be increasingly defined and met in practice.The 'big four' species, perennial ryegrass, phalaris, cocksfoot and tall fescue, will continue to be the most widely sown species in temperate regions for many decades, with the latter 3 increasing most in area and genetic differentiation. However, species diversification will continue, especially with native grasses, legumes, and shrubs from fertile regions of Australia and exotics from little-explored parts of the world, such as South Africa, western North and South America, coastal Caucasus, and Iraq–Iran. By contrast, the recent high rate of species diversification in the tropics and subtropics will probably give way to a much lower rate of cultivar development by refinement and diversification within the established species. Domestication of native grasses will continue for amenity, recreational, land protection, and grazing purposes. As seed harvesting technologies and ecological knowledge improve, natural stands will become increasingly important as local sources of seed. It is suggested that many native grasses have been greatly changed by natural selection so as to withstand strong competition from introduced species under conditions of higher soil fertility and grazing pressure. Conversely, some introduced species are being selected consciously and naturally to persist in regions with irregular rainfall and less fertile soils. Therefore, the distinction between native and introduced grasses may be disappearing, and many populations of native species could now be as foreign to the habitats of pre-European settlement as are populations of introduced species that have been evolving here for 50–200 years. Methods used for genetic improvement will continue to be selection among both overseas accessions and the many native and introduced populations that have responded to natural selection in Australia. As well, there will be deliberate recurrent crossing and selection programs in both native and introduced species for specific purposes and environments. Increasingly, molecular biology methods will complement traditional ones, at first by the provision of DNA markers to assist the selection of complex traits, and for proving distinctness to obtain Plant Breeders' Rights for new cultivars. Later, genetic engineering will be used to manipulate nutritive value, resistance to fungal and viral diseases, and breeding systems, especially cytoplasmic male sterility and apomixis, to utilise heterosis in hybrid cultivars of grasses, particularly for dairying and intensive meat production.Areas where the practice and management of grass breeding and selection programs could be improved are highlighted throughout the review, and reiterated in a concluding statement. Most problems appear to stem from inadequate training in population ecology, population genetics, evolution, and quantitative inheritance.
26
Whelan, BR. "Uptake of selenite fertilizer by subterranean clover pasture in Western Australia". Australian Journal of Experimental Agriculture 29, n. 4 (1989): 517. http://dx.doi.org/10.1071/ea9890517.
Testo completoAbstract (sommario):
. Subterranean clover (Trifolium subterraneum) based pastures were fertilised with sodium selenite at 9 rates from 0 to 800 g Se/ha on 2 sites in 1983. In order to measure the residual value in 1984 and 1985, further applications of sodium selenite were superimposed on the original 9 treatments. Green pasture was sampled annually, dry pasture was sampled once, only in 1984 and the concentration of selenium in the pasture was measured. The sampled pasture was sorted into 2 components: subterranean clover, and non-subterranean clover. Except for the third site that had a quadratic response for the non-subterranean clover component of the pasture, the concentration of selenium in plants increased linearly with application rate. The selenium concentration in subterranean clover was lower than that in the other species in the pasture. Differences between years were large: in 1985, the concentration in plant material was twice that in 1983 and 1984. The dry summer feed had higher concentrations of selenium than the green pasture. The residual value of selenite was 25% in the first year and 15% in the second year. Adequate dietary levels of selenium for sheep would require an annual application of about 200 g sodium selenite/ha to these soils.
27
Sanford, P., X. Wang, K. D. Greathead, J. H. Gladman e J. Speijers. "Impact of Tasmanian blue gum belts and kikuyu-based pasture on sheep production and groundwater recharge in south-western Western Australia". Australian Journal of Experimental Agriculture 43, n. 8 (2003): 755. http://dx.doi.org/10.1071/ea02226.
Testo completoAbstract (sommario):
The effect of Tasmanian blue gum (Eucalyptus globulus) belts and kikuyu (Pennisetum clandestinum) grass on livestock production and groundwater recharge was studied in the high rainfall zone (>600 mm/year) of south-western Western Australia from 1998 to 2001. The objective was to identify optimum combinations of tree belts and pasture for sustainable livestock production and the prevention of secondary salinisation. Treatments were annual pasture, in competition with trees at different orientations (east, west and south), kikuyu pasture in competition with trees at one orientation (west), compared with pasture in the absence of tree competition. Plots had 0, 20 or 36% of their area within 10 m of the tree belt where tree–pasture competition would be expected. Plots (0.48 ha) were stocked with Merino wether hoggets at 12 DSE/ha on annual pastures and 14 DSE/ha on kikuyu pastures. Additional sheep were placed on plots in spring and the annual pasture was destocked in autumn.Within the growing season, herbage mass was similar across both control treatments as a result of varying stock numbers. However, in summer and autumn the kikuyu control contained between 350 and 4900 kg DM/ha more herbage than the corresponding annual pasture. While both pastures accumulated similar amounts of herbage in 1998 and 2000, kikuyu accumulated more in 1999 (11 900 v. 9800 kg DM/ha) as a result of summer rain. Competition from tree belts significantly reduced adjacent annual pasture herbage accumulation (16% average reduction), although there was no difference among the levels of competition. Trees did not significantly affect adjacent kikuyu pasture herbage accumulation. Both carrying capacity and clean wool production per hectare were significantly higher on kikuyu pasture in 1999 and 2000. Tree competition also significantly reduced the carrying capacity of neighbouring annual and kikuyu pasture by an average of 10%. Clean wool production per hectare was significantly lower on annual pasture in combination with trees (11% reduction on average), but there was less effect of competition on kikuyu pasture. The kikuyu pasture used 115, 57 and 132 mm more water than the annual pasture in 1999, 2000 and 2001, respectively. The soil water deficit beneath the trees exceeded that below both control pastures by between 297 and 442 mm.Although the addition of tree belts to annual pasture provided substantial reductions in groundwater recharge, producers would also have to accept losses in livestock production. While kikuyu alone provided significant increases in livestock production and substantial reductions in groundwater recharge, the best compromise was kikuyu in combination with tree belts.
28
Bolland, M. D. A., J. S. Yeates e M. F. Clarke. "Comparing different sources of sulfur for high-rainfall pastures insouth-western Australia". Australian Journal of Experimental Agriculture 43, n. 10 (2003): 1221. http://dx.doi.org/10.1071/ea02146.
Testo completoAbstract (sommario):
The dry herbage yield increase (response) of subterranean clover (Trifolium subterraneum L.)-based pasture (>85% clover) to applications of different sources of sulfur (S) was compared in 7 field experiments on very sandy soils in the > 650 mm annual average rainfall areas of south-western Australia where S deficiency of clover is common when pastures grow rapidly during spring (August–November). The sources compared were single superphosphate, finely grained and coarsely grained gypsum from deposits in south-western Australia, and elemental S. All sources were broadcast (topdressed) once only onto each plot, 3 weeks after pasture emerged at the start of the first growing season. In each subsequent year, fresh fertiliser-S as single superphosphate was applied 3 weeks after pasture emerged to nil-S plots previously not treated with S since the start of the experiment. This was to determine the residual value of sources applied at the start of the experiment in each subsequent year relative to superphosphate freshly-applied in each subsequent year. In addition, superphosphate was also applied 6, 12 and 16 weeks after emergence of pasture in each year, using nil-S plots not previously treated with S since the start of the experiment. Pasture responses to applied S are usually larger after mid-August, so applying S later may match plant demand increasing the effectiveness of S for pasture production and may also reduce leaching losses of the applied S.At the same site, yield increases to applied S varied greatly, from 0 to 300%, at different harvests in the same or different years. These variations in yield responses to applied S are attributed to the net effect of mineralisation of different amounts of S from soil organic matter, dissolution of S from fertilisers, and different amounts of leaching losses of S from soil by rainfall. Within each year at each site, yield increases were mostly larger in spring (September–November) than in autumn (June–August). In the year of application, single superphosphate was equally or more effective than the other sources. In years when large responses to S occurred, applying single superphosphate later in the year was more effective than applying single superphosphate 3 weeks after pasture emerged (standard practice), so within each year the most recently applied single superphosphate treatment was the most effective S source. All sources generally had negligible residual value, so S needed to be applied each year to ensure S deficiency did not reduce pasture production.
29
Ward, P. R., R. A. Lawes e D. Ferris. "Soil-water dynamics in a pasture-cropping system". Crop and Pasture Science 65, n. 10 (2014): 1016. http://dx.doi.org/10.1071/cp14046.
Testo completoAbstract (sommario):
Pasture cropping is a farming system in which annual crops are sown into established perennial pastures. It may provide environmental benefits such as increased groundcover and reduced deep drainage, while allowing traditional crop production in the Mediterranean-style climate of south-western Australia. In this research, we investigated deep drainage and the temporal patterns of water use by a subtropical perennial grass, annual crops, and a pasture-cropping system over a 4-year period. Both the pasture and pasture-cropped treatments reduced deep drainage significantly, by ~50 mm compared with the crop treatment. Competition between the pasture and crop components altered patterns of average daily water use, the pasture-cropped treatment having the highest water use for July, August and September. Consequently, water-use efficiency for grain production was lower in the pasture-cropped plots. This was offset by pasture production, so that over a full 12-month period, water-use efficiency for biomass production was generally greater for the pasture-cropped plots than for either the pasture or crop monocultures. Pasture cropping may be a viable way of generating sustainable economic returns from both crop and pasture production on sandy soils of south-western Australia.
30
Bird, P. R., T. T. Jackson e K. W. Williams. "Effect of synthetic windbreaks on pasture growth in south-western Victoria, Australia". Australian Journal of Experimental Agriculture 42, n. 6 (2002): 831. http://dx.doi.org/10.1071/ea02017.
Testo completoAbstract (sommario):
The impact of a synthetic windbreak on the growth of subterranean clover and perennial ryegrass pasture in the cool-temperate zone of south-western Victoria was investigated over 2 years. Four square plots (10 m sides) at each of 2 sites were fenced with wire mesh 1.2 m tall in 1996 and 1997. Two plots at each site were sheltered with synthetic mesh of 50% porosity attached to the wire mesh. The open wind speed averaged 3.6 m/s in 1996 and 3.1�m/s in 1997. Winds exceeded 6 m/s for 4–23% and 2–8% of the time in 1996 and 1997, respectively. There were small but significant differences in temperature between the sheltered and open plots. The mean daily temperature was 0–0.4°C warmer with shelter. Temperatures in the shelters were always higher from 0900 to 1800�hours, the differences ranging from 0.1 to 0.9°C. Conversely, lower temperatures (a maximum difference of 0.4°C) usually occurred in the shelters from 1800 to 0600 hours. The mean daily relative humidity was 1.4–3.1% greater in shelter than in the open and the maximum difference was 3.8%. There was a significant (P< 0.01) effect of shelter on pasture growth in both years. In terms of total production over both years, the results indicate a small but consistent increase in pasture growth of about 9% for sheltered v. open plots at both sites. There was a clear seasonal effect of shelter, with greater production in autumn–winter, and a trend towards greater production in open plots during very wet periods. The results indicate that responses of pasture plants to shelter in the cool-temperate zone of Australia may be modest, and difficult to determine in field experiments, but shelter should contribute significantly to animal production because of improved plant growth in times of scarcity and reduced expenditure of energy for maintenance. Artificial shelters may provide the best means of testing the likely response to shelter of other pasture species or crops.
31
Barbetti, MJ. "Infection studies with Cercospora zebrina on pasture legumes in Western Australia". Australian Journal of Experimental Agriculture 25, n. 4 (1985): 850. http://dx.doi.org/10.1071/ea9850850.
Testo completoAbstract (sommario):
The effects of inoculum level, and temperature and humidity regimes on the development of Cercospora blackstem disease (caused by Cercospora zebrina) in subterranean clover (Trifolium subterraneum) were investigated. Mycelial fragments were an effective and reliable inoculum. The incidence, severity, and the rate of disease development increased with increasing period of high humidity after inoculation and with increasing concentrations of inoculum. Disease was greatest at 18/13� (12/12 h, day/ night), followed by 21/16�C, and then l5/10�C While all cultivars of T. subterraneum sprayed with hyphal fragments of C. zebrina became infected, Trikkala and Larisa showed some resistance. Of the alternative pasture legumes, lucerne (Medicago sativa), medic (M. littoralis, M. truncatula), drooping-flowered clover (T. cernuum), strawberry clover (T. fragiferum), rose clover (T. hirtum) and white clover (T. repens) were all susceptible; only serradella (Ornithopus compressus) was resistant.
32
Dolling, P. J. "Water use and drainage under phalaris, annual pasture, and crops on a duplex soil in Western Australia". Australian Journal of Agricultural Research 52, n. 2 (2001): 305. http://dx.doi.org/10.1071/ar99167.
Testo completoAbstract (sommario):
Rising water tables in southern Western Australia are causing waterlogging and salinity problems. These issues are related to a lower level of water use by annual plants than by the native vegetation. Phalaris can use more water than annual pastures and crops because of deeper rooting characteristics and longer growing season. However, there is limited information on the water use of phalaris in the Western Australian environment. There is also very little information on water balances under annual crops and pastures outside the growing season. A field experiment was carried out on a duplex soil between March 1994 and March 1999. Annual rainfall varied between 321 and 572 mm. The study examined soil water content, deep drainage, and productivity of phalaris-based pasture, continuous annual pasture, annual pasture–wheat rotation, and a wheat–lupin rotation. The results showed that the phalaris-based pasture after the establishment year was 25% (1.9 t dry matter/ha) more productive than continuous annual pasture, with the main difference occurring in late spring–early summer. The phalaris-based pasture used, on average, 45 mm/year more water and reduced drainage below 1 m by 44 mm/year compared with the annual pastures and crops. Total drainage below 1 m was 30 mm under the phalaris-based pasture and 74 mm under annual pasture. The greater water use in the phalaris-based pasture occurred in late spring and early summer. Although differences in total biomass per year occurred between wheat in different rotations there was no difference in the soil water storage prior to the break of the season. There was also no difference in the soil water balance between any of the annual crops and pastures. Differences in soil water storage did occur in some years in October but disappeared by May the following year.
33
Schut, A. G. T., S. G. Gherardi e D. A. Wood. "Empirical models to quantify the nutritive characteristics of annual pastures in south-west Western Australia". Crop and Pasture Science 61, n. 1 (2010): 32. http://dx.doi.org/10.1071/cp08438.
Testo completoAbstract (sommario):
The objective of this paper is to quantify the magnitude of the major sources of variation, which affect in vitro digestibility (DMD) and concentrations of neutral detergent fibre (NDF), acid detergent fibre (ADF), and crude protein (CP) of annual pastures in Mediterranean-type climate zones. Four experiments were conducted in the south-west of Western Australia in 2006–07 and 2007–08, where the supply of nitrogen, phosphorous, potassium, or sulfur and pasture types were varied. Effects of seasonality, fertiliser application, pasture type, and site were analysed with an auto-regression maximum likelihood procedure. Temperature sum was used to explain the seasonal differences in DMD, CP, NDF, and ADF. Seasonality explained 82, 79, 79, and 62% of the total variation in DMD, NDF, ADF, and CP, respectively, with only an additional 5, 5, 6, and 24% being explained by the combined effects of site/management, fertiliser application, and pasture type. The differences in DMD, NDF, ADF, and CP, between sites, were 2.3–6.0%, 4.6–18.7%, 5.8–8.6%, and 1.5–17.4%, respectively. Pasture types differed by 6.6–9.5%, 9.0–11.4%, 3.1–6.1%, and 5.1–5.2% for DMD, NDF, ADF, and CP, respectively. The differences between sites and pasture types were markedly larger for CP, NDF, and ADF than for DMD. Fertiliser application did not affect nutritive characteristics, with the exception of N application rates on CP. It was concluded that the seasonality model captured nearly all of the temporal variation in DMD, NDF, and ADF but not in CP. The spatial variation in DMD was mostly determined by pasture type. By comparison, NDF and ADF were most strongly affected by grazing management, and CP by the availability of N.
34
Bird, P. R., T. T. Jackson, G. A. Kearney e K. W. Williams. "Effect of two tree windbreaks on adjacent pastures in south-western Victoria, Australia". Australian Journal of Experimental Agriculture 42, n. 6 (2002): 809. http://dx.doi.org/10.1071/ea02016.
Testo completoAbstract (sommario):
The effects of 2 tree windbreaks on pasture production in adjoining paddocks were assessed over 4 years in a cool-temperate climate, perennial pasture area in south-western Victoria, Australia. The Willandra windbreak was 2 rows of direct-sown black wattle (Acacia mearnsii) aligned south-east–north-west. The Helm View windbreak was 4 rows of mixed Eucalyptus, Casuarina and Acacia spp., aligned east–west. Pastures at both sites had been sown to perennial ryegrass and subterranean clover. Wind direction data indicated that the north-eastern and south-western paddocks at Willandra were sheltered 39 and 28% of the time, respectively. The northern and southern paddocks at Helm View were sheltered 34 and 42% of the time, respectively. The relationship of rainfall with wind speed and direction was examined to indicate the potential of windbreaks of various orientations to protect livestock. The windbreaks had clear effects on pasture production in the competition zone along the margins of the windbreak. Average pasture production at Willandra in the zone 0.5–0.75 H (where H is the windbreak height) was 69% of open yield; production in the 0.9–1.5 H zone was 96%. At Helm View, production in the zone 0.7–1.0 H was 74% of open yield, with 81% in the zone 1.1–1.5 H. Averaged over all years, both windbreaks had no effect on pasture growth in the 2–10 H sheltered zone, although in some years there were small significant growth increases at parts of that zone in certain paddocks. Periodic soil moisture measurements at Willandra showed that water use was greater in the competition zone near the windbreak, with a difference in summer water content of the 1.2 m profile of at least 20 mm between soil 4.6 m from the windbreak and further away. The difference was due to greater water use from the deepest part of the profile. No other effects of the windbreak on soil water content were observed.
35
Kaur, K., R. K. Jalota, D. J. Midmore e J. Rolfe. "Pasture production in cleared and uncleared grazing systems of central Queensland, Australia". Rangeland Journal 27, n. 2 (2005): 143. http://dx.doi.org/10.1071/rj05012.
Testo completoAbstract (sommario):
Clearing land of trees and introducing exotic pastures to enhance pasture and cattle production and hence enterprise financial performance are widely practised in Queensland. The results from many previous studies on tree clearing have emphasised the gains in pasture production, but over periods of less than 10–15 years after clearing. The present study questioned the sustainability of pasture production in cleared systems over a longer time-frame (>10 years of clearing). For this, three different age groups of clearing i.e. 5 year, 11–13 year and 33 year were selected in each of 3 major types of tree communities i.e. Eucalyptus populnea, E. melanophloia and Acacia harpophylla in central Queensland. Paired comparisons of cleared and uncleared (intact) pasture systems were selected for each age group of clearing. The results suggest that the initial gains in pasture production upon clearing were compatible with published studies. However, for longer periods of time since clearing, the gains in pasture production were not sustained and were accompanied by risks of land degradation and loss of pasture plant diversity. For E. populnea and A. harpophylla, the maximum benefits from clearing were achieved at 13–15 years whereas for E. melanophloia, any benefits existed only over a short period of 5–6 years. The study emphasises that each tree community exhibits a specific response with regard to the duration of increased pasture production following clearing. To estimate the total benefits from tree clearing in pasture development, it is important to consider both monetary benefits and non-monetary losses from clearing for different types of tree communities.
36
McDowall, M. M., D. J. M. Hall, D. A. Johnson, J. Bowyer e P. Spicer. "Kikuyu and annual pasture: a characterisation of a productive and sustainable beef production system on the South Coast of Western Australia". Australian Journal of Experimental Agriculture 43, n. 8 (2003): 769. http://dx.doi.org/10.1071/ea02230.
Testo completoAbstract (sommario):
Production parameters and water use of kikuyu (Pennisetum clandestinum) and annual-based pastures were monitored for a beef weaner production system from 1998 to 2000 in a paddock-scale demonstration on the south-east coast of Western Australia. A paired paddock (40–105 ha) comparison was carried out between a kikuyu-based pasture (DSKikuyu) and temperate annual pasture (DSAnnual), with comparative measurements covering pasture production, composition and quality, and soil water deficits and drainage. The stocking rates for the paddocks were determined by the pasture productivity and cow P8 fat depth in the 'lactation phase' (April–December), and by sward management and soil stability imperatives in the 'dry cow phase' (January–March). Cow liveweight and P8 fat depth and calf liveweight were compared during the 'lactation phase'. Kikuyu and annual pasture had similar carrying capacities through the 'lactation phase'. Kikuyu pasture carried more animals than annual pasture through the 'dry cow phase' (late summer and autumn) in all years. During late autumn, cattle were destocked from the annual pasture to reduce the risk of wind erosion and 'crash grazed' on the kikuyu pasture so as to reduce competition between kikuyu and regenerating annual grass and legume species. The comparative quality and productivity of the kikuyu pasture in the lactation phase (winter and spring) was positively correlated with the level of winter legume present. When a similar level of winter legume was measured in the kikuyu pasture relative to the annual pasture (in 1998), the pasture quality, cow liveweight and condition and calf weaning weights were all comparable between the 2 pasture types. When a low legume component was recorded in the kikuyu pasture, the pasture quality and cow liveweight and condition were poorer than the annual pasture. The kikuyu pasture growing on deep sandy soil developed a larger (mean 37 mm) soil water deficit than the annual pasture over the measurement period, and in particular from November to March. When integrated over a farm where kikuyu covers 40% of the total area, as was the case in this experiment, the resulting deep drainage was calculated to be just over half that of an equivalent whole farm of annual pasture. Over the 3 years of monitoring, the combined system of annual and kikuyu pasture was calculated to have an annual gross margin 19% higher than the annual pasture alone. The major source of difference was no requirement for supplementary feed in the kikuyu–annual pasture system. This difference was limited however, by lighter post-weaning sale weights of cull cows from the kikuyu pasture in 'poor legume' years. There was no difference of calf weaning weights between treatments.There is considerable opportunity to improve on this gross margin, through achieving a consistent strong presence of legume in the kikuyu pasture through winter and spring.
37
Semple, WS, TB Koen e IA Cole. "Establishing Native Grasses in Degraded Pastures of Central Western New South Wales." Rangeland Journal 21, n. 2 (1999): 153. http://dx.doi.org/10.1071/rj9990153.
Testo completoAbstract (sommario):
Renewed interest in native grasses in recent years has led to the release of a small number of cultivars but for most native species, seed is only available from wild stands. Seed can be harvested with a brush harvester but cleaning seed to a level that will allow it to pass through conventional sowing equipment is often difficult. Techniques for successful field establishment of native species are still not fully understood. From 1993 to 1995, native grasses (mainly warm-season types) were sown in early spring in exotic pastures at a number of sites in the Central West of NSW. Various seedbed types, sowing methods and species were evaluated in six experiments. In five of the experiments, establishment was low for most species - a result attributed primarily to weed competition. At one site in 1994, however, the combination of a cultivated seedbed, 18 months of pre-sowing weed control, relatively low soil fertility and a high sowing rate resulted in high emergence of most species and acceptable survival of Paspalidium jubi$orum, Themeda australis and to a lesser extent, Chloris ventricosa and C. truncata. Key words: exotic species, native species, emergence, survival, seedbed, weed control.
38
Smith, G. T. "Ecology of the Western WhipbirdPsophodes nigrogularisin Western Australia". Emu - Austral Ornithology 91, n. 3 (agosto 1991): 145–57. http://dx.doi.org/10.1071/mu9910145.
Testo completo
39
Green, DR. "Rangeland restoration projects in western New South Wales." Rangeland Journal 11, n. 2 (1989): 110. http://dx.doi.org/10.1071/rj9890110.
Testo completoAbstract (sommario):
The semi-arid to arid Western Division of New South Wales has suffered significant levels of land degradation due to overstocking by domestic animals and rabbits. Three major forms of land degradation are identified, soil erosion, woody weed growth and pasture quality decline. Restoration techniques developed and applied by the New South Wales Soil Conservation Service are presented and discussed. The successful techniques presented are contour furrowing and waterponding for sheet eroded or scalded areas, fire and blade ploughing for woody weed control and grazing management to reverse pasture decline. The lack of knowledge on pasture species responses to grazing management stimuli is highlighted.
40
Hill, MJ. "Potential adaptation zones for temperate pasture species as constrained by climate: a knowledge-based logical modelling approach". Australian Journal of Agricultural Research 47, n. 7 (1996): 1095. http://dx.doi.org/10.1071/ar9961095.
Testo completoAbstract (sommario):
Potential adaptation zones were modelled for major temperate pasture species using climate data and knowledge-based logical rules. A GIs database was constructed using a 0.025 degree digital elevation model and the Australian Climate Surfaces to create layers of monthly mean climate data for Australia. Soil pH maps for New South Wales, Victoria, and south-eastern South Australia were digitised and added to the database. Simple models using logical operators were constructed using estimates of temperature and aridity thresholds for the main temperate pasture species. The logical models were executed using primary and derived climate layers to create raster maps of potential adaptation zones for pasture species in eastern and south-western Australia. Areas of adaptation on freehold/leasehold land were expressed relative to a potential temperate pasture adaptation zone described by the lower (arid) limit of annual legume adaptation in temperate Australia and the northern limit of lucerne adaptation. Potential adaptation within this area ranged from 66% for lucerne down to <20% for perennial ryegrass in eastern Australia, and 93% for subterranean clover down to zero for perennial ryegrass in south-western Australia. Utility of the species adaptation zones could be enhanced using soil pH maps: a zone for serradella in NSW was refined by restricting adaptation to areas of climatic suitability with low soil pH. Maps for lucerne and Mount Barker subterranean clover showed good agreement with validation data for NSW. The zones may be readily adjusted by simple changes to parameter values in the algorithms. This knowledge-based approach has potential as an aid to targeting resources for plant improvement or to provide advice for more efficient utilisation of existing commercial pasture plants.
41
Thomas, Dean T., Roger A. Lawes, Katrien Descheemaeker e Andrew D. Moore. "Selection of crop cultivars suited to the location combined with astute management can reduce crop yield penalties in pasture cropping systems". Crop and Pasture Science 65, n. 10 (2014): 1022. http://dx.doi.org/10.1071/cp13436.
Testo completoAbstract (sommario):
Pasture cropping is an emerging farming-systems practice of southern Australia, in which winter grain crops are sown into an established stand of a winter-dormant, summer-growing perennial pasture. There is a pressing need to define times, locations and climates that are suitable for pasture cropping. To evaluate effects of management interventions, agro-environment, and possible interactions on crop and pasture productivity associated with pasture cropping, an AusFarm® simulation model was built to describe a pasture-cropping system based on annual crop and subtropical grass. The model was parameterised using data from field research on pasture cropping with barley cv. Buloke and a C4 subtropical grass, Gatton panic (Panicum maximum cv. Gatton), conducted at Moora, Western Australia. The simulation was run over 50 years using the historical climate data of five southern Australian locations (Cunderdin, Jerdacuttup, Mingenew, and Moora in Western Australia, and Karoonda in South Australia). Two wheat cultivars and one barley crop were considered for each location, to examine the impact of crop phenology on this farming system. Jerdacuttup and Moora favoured pasture cropping, with average barley-yield penalties of 10 and 12%. These locations were characterised by colder growing seasons, more plant-available water at anthesis, and more winter–spring rain. The cereal crops did not rely on stored soil moisture, growing instead on incident rain. The winter–spring growth of the Gatton panic pasture was highest at Mingenew. This generated a high yield penalty, 38% loss under pasture cropping, compared with the other locations. Changing the efficacy of a herbicide application to the pasture when the crop was sown had a strong effect on yield. Yield penalties at Moora and Mingenew reduced to 7 and 29%, respectively, when the proportion of live biomass killed by the herbicide was doubled. Utilisation of soil moisture by the Gatton panic pasture during summer and early autumn had little effect on subsequent grain yield, whereas reduced pasture growth during the winter–spring growing period had a substantial effect on crop yield. Pasture cropping can therefore succeed in agro-climatic regions where crops can be grown on incident rain and pasture growth is suppressed through low temperature or herbicide. Perennial pasture growth should be minimised during the crop growing period through the management of crop sowing date, nitrogen fertiliser application and C4 grass suppression to minimise the effect on stored soil water at crop anthesis.
42
Bolland, M. D. A., e I. F. Guthridge. "Responses of intensively grazed dairy pastures to applications of fertiliser nitrogen in south-western Australia". Australian Journal of Experimental Agriculture 47, n. 8 (2007): 927. http://dx.doi.org/10.1071/ea06014.
Testo completoAbstract (sommario):
For the first time, we quantified pasture dry matter (DM) responses to applied fertiliser nitrogen (N) for intensively grazed, rain-fed, dairy pastures on sandy soils common in the Mediterranean-type climate of south-western Australia. The pastures are composed of subterranean clover (Trifolium subterraneum L.) and annual and Italian ryegrass (Lolium rigidum Gaud. and L. multiflorum Lam.). Six rates of N, as urea (46% N), were applied to 15 m by 15 m plots four times during 2002 and after each of the first 5–7 grazings in 2003 and 2004, throughout the typical April–October growing season. Total rates of N applied in the first year of the experiments were 0, 60, 120, 160, 200 and 320 kg N/ha, which were adjusted in subsequent years as detailed in the ‘Materials and methods’ section of this paper. The pastures in the experiments were rotationally grazed, by starting grazing when ryegrass plants had 2–3 leaves per tiller. The amount of pasture DM on each plot was measured before and after each grazing and was then used to estimate the amount of pasture DM consumed by the cows at each grazing for different times during the growing season. Linear increases (responses) of pasture DM to applied N occurred throughout the whole growing season when a total of up to 320 kg N/ha was applied in each year. No maximum yield plateaus were defined. Across all three experiments and years, on average in each year, a total of ~5 t/ha consumed DM was produced when no N was applied and ~7.5 t/ha was produced when a total of 200 kg N/ha was applied, giving ~2.5 t/ha increase in DM consumed and an N response efficiency of ~12.5 kg DM N/kg applied. As more fertiliser N was applied, the proportion of ryegrass in the pasture consistently increased, whereas clover content decreased. Concentrations of nitrate-N in the DM consistently increased as more N was applied, whereas concentrations of total N, and, therefore, concentration of crude protein in the DM, either increased or were unaffected by applied N. Application of N had no effect on concentrations of other mineral elements in DM and on dry matter digestibility and metabolisable energy of the DM. The results were generally consistent with findings of previous pasture N studies for perennial and annual temperate and subtropical pastures. We have shown that when pasture use for milk production has been maximised in the region, it is profitable to apply fertiliser N to grow extra DM consumed by dairy cows; conversely, it is a waste of money to apply N to undergrazed pastures to produce more unused DM.
43
Loss, SP, GSP Ritchie e AD Robson. "Effect of lupins and pasture on soil acidification and fertility in Western Australia". Australian Journal of Experimental Agriculture 33, n. 4 (1993): 457. http://dx.doi.org/10.1071/ea9930457.
Testo completoAbstract (sommario):
An 'across the fence' comparison of farmer paddocks with nearby virgin bush sites was made at 3 locations, to measure the effects of lupins and subterranean clover based pastures on the chemical properties of the soil. Estimated rates of acidification in the 0-60 cm depth were 0.29-0.55 kmol H+/ha.year for wheat-lupin paddocks and 0.16-0.2 1 kmol H+/ha .year for pasture paddocks. A significant proportion of this acidification occurred below 20 cm, particularly in the lupin paddocks (up to 70% of the total). Severe water repellency had developed at 1 location that had produced 30 lupin crops with the occasional wheat crop. Despite these detrimental effects, lupins maintained soil mineral nitrogen and organic matter contents and electrical conductivities similar to those in pasture paddocks, even though the soils in the lupin rotations had been sown to wheat more frequently.
44
Thomson, C. J., C. K. Revell, N. C. Turner, M. A. Ewing e I. F. Le Coultre. "Influence of rotation and time of germinating rains on the productivity and composition of annual pastures in Western Australia". Australian Journal of Agricultural Research 49, n. 2 (1998): 225. http://dx.doi.org/10.1071/a94082.
Testo completoAbstract (sommario):
A long-term rotation experiment located in south-western Australia was used to measure the effect of rotation and time of germinating rains on the productivity and botanical composition of grazed annual pastures in 2 contrasting seasons in an environment with an average annual rainfall of 325 mm. The density of self-regenerating seedlings of subterranean clover (Trifolium subterraneum), capeweed (Arctotheca calendula), and grasses (Lolium rigidum, Hordeum leporinum, Bromus diandrus) was greatly increased (approx. 3 times the density) when there was a second year of pasture after crop compared with the first year after crop. The lower plant density resulted in first-year pastures having only about 33% of the autumn biomass accumulation of second-year pastures. This difference in early pasture growth had no effect on total pasture production in 1992, but in 1993 total pasture production was 30% greater in second-year pastures compared with first-year pastures. Botanical composition varied between and within seasons with the percentage of subterranean clover increasing throughout the season and the percentage of capeweed decreasing throughout the season. Grasses comprised <20% of the biomass in all seasons and treatments. Production of subterranean clover seed in 1993 was higher in a 1 : 2 crop-pasture rotation than in a 1 : 1 crop-pasture rotation and direct drilling in the cropping phase increased seed set compared with conventional tillage in both 1 : 1 and 1 : 2 crop-pasture rotations. Capeweed seedlings emerged in large numbers after rainfall between February and May and subsequently showed a relative growth rate twice that of subterranean clover and the grasses, but exclusion of rainfall until June resulted in a significant reduction in the emergence of capeweed seedlings. Additionally, capeweed had a lower rate of seedling survival compared with other pasture species, and this is contrary to observations by other researchers that capeweed is highly resistant to moisture stress during early growth.
45
Moore, G. A., P. Sanford, P. J. Dolling e D. Real. "The challenges of developing resilient perennial pastures for a Mediterranean environment – a review for Western Australia". Crop and Pasture Science 72, n. 9 (2021): 613. http://dx.doi.org/10.1071/cp20304.
Testo completoAbstract (sommario):
Perennial pastures are the dominant feedbase in many regions of the world, and offer several advantages when compared with an annual pasture system. In Western Australia (WA) there has been a concerted effort over seven decades to develop new perennial pasture options and expand the adoption of suitable species. The agricultural region of WA (i.e. south-western Australia) is characterised by a Mediterranean climate where the 5–7 month summer drought has proved a considerable challenge with only a small number of the many promising species being adopted commercially. Research, development, and extension have covered a wide range of herbaceous perennial legumes, leguminous and native shrubs, herbs, and temperate and warm season grasses. This paper reviews the literature to determine whether a perennial pasture must satisfy the following criteria to be successful and widely adopted in south-western Australia: (i) sourced from a similar Mediterranean environment and adapted to the target soils; (ii) have a relative advantage over the annual-based system it replaces; (iii) a robust management package; and (iv) a viable seed supply. The findings of this review highlight that perennial pastures must indeed satisfy multiple criteria to be commercially successful. Notably, the requirement for the source of the germplasm to have a good match between climate and soils is less clear because some of the commercially successful species come from diverse environments. We conclude with some key learnings for future perennial pasture development as climate change intensifies the research challenge and the drive for producers to adapt.
46
Bolland, M. D. A., e I. F. Guthridge. "Determining the fertiliser phosphorus requirements of intensively grazed dairy pastures in south-western Australia with or without adequate nitrogen fertiliser". Australian Journal of Experimental Agriculture 47, n. 7 (2007): 801. http://dx.doi.org/10.1071/ea05184.
Testo completoAbstract (sommario):
Fertiliser phosphorus (P) and, more recently, fertiliser nitrogen (N) are regularly applied to intensively grazed dairy pastures in south-western Australia. However, it is not known if applications of fertiliser N change pasture dry matter (DM) yield responses to applied fertiliser P. In three Western Australian field experiments (2000–04), six levels of P were applied to large plots with or without fertiliser N. The pastures were rotationally grazed. Grazing started when ryegrass plants had 2–3 leaves per tiller. Plots were grazed in common with the lactating dairy herd in the 6-h period between the morning and afternoon milking. A pasture DM yield response to applied N occurred for all harvests in all three experiments. For the two experiments on P deficient soil, pasture DM yield responses also occurred to applications of P. For some harvests when no fertiliser N was applied, probably because mineral N in soil was so small, there was a small, non-significant pasture DM response to applied P and the P × N interaction was highly significant (P < 0.001). However, for most harvests there was a significant pasture DM response to both applied N and P, and the P × N interaction was significant (P < 0.05–0.01), with the response to applied P, and maximum yield plateaus to applied P, being smaller when no N was applied. Despite this, for the significant pasture DM responses to applied P, the level of applied P required to produce 90% of the maximum pasture DM yield was mostly similar with or without applied N. Evidently for P deficient soils in the region, pasture DM responses to applied fertiliser P are smaller or may fail to occur unless fertiliser N is also applied. In a third experiment, where the soil had a high P status (i.e. more typical of most dairy farms in the region), there was only a pasture DM yield response to applied fertiliser N. We recommend that fertiliser P should not be applied to dairy pastures in the region until soil testing indicates likely deficiency, to avoid developing unproductive, unprofitable large surpluses of P in soil, and reduce the likelihood of P leaching and polluting water in the many drains and waterways in the region. For all three experiments, critical Colwell soil test P (a soil test value that was related to 90% of the maximum pasture DM yield), was similar for the two fertiliser N treatments.
47
Dolling, PJ, WM Porter e IC Rowland. "Acidification rates in the central wheatbelt of Western Australia. 2. On a sandy duplex soil". Australian Journal of Experimental Agriculture 34, n. 8 (1994): 1165. http://dx.doi.org/10.1071/ea9941165.
Testo completoAbstract (sommario):
The rate and mechanisms of acidification were determined on a sandy duplex soil (depth of sand 30-45 cm) under a cereal-annual pasture rotation in Western Australia. We also evaluated the effect of rotation (intensity of cropping) on relative acidification of a sandy duplex soil. Rate of acidification was based on a linear regression analysis between soil pH and years since clearing. Sites were sampled to a depth of 50 cm in 10-cm increments and measurements included soil pH, pH buffering capacity, and bulk density. The effect of different rotations on the acidification rate was determined by soil sampling a rotation experiment which had been established for 25 years. Sampling and measurements were similar to the regression analysis. From regression, the rate of acidification for the profile was 0.15 kmol H+/ha.year, requiring 7.7 kg CaCO3 to neutralise. Most of the acidification could be accounted for by removal of alkaline products. Acidification was occurring to a depth of 30 cm, the acidification rate decreasing with depth. In the surface 20 cm the pH decline was 0.005-0.006 units/year. In the rotation experiment, the rate of acidification relative to continuous wheat without fertiliser nitrogen (N) ranged from 0.35 kmol H+/ha .year (17.5 kg CaCO3) for continuous wheat with fertiliser N to 0.92 kmol H+/ha. year (45.8 kg CaCO3) for continuous pasture. Between these rates was 1 year pasture-1 year cereal (0.41 kmol H+/ha. year, 20.5 kg CaCO3) and 2 years pasture-1 year cereal (0.82 kmol H+/ha . year, 41.2 kg CaCO3). Acidification was occurring to 60 cm depth in all rotations, mostly due to nitrate leaching, removal of alkaline products, and build-up of organic matter.
48
Nichols, P. G. H., M. J. Barbetti, G. A. Sandral, B. S. Dear, C. T. de Koning, D. L. Lloyd, P. M. Evans, A. D. Craig, P. Si e M. P. You. "Coolamon subterranean clover (Trifolium subterraneum L. var. subterraneum)". Australian Journal of Experimental Agriculture 47, n. 2 (2007): 223. http://dx.doi.org/10.1071/ea05282.
Testo completoAbstract (sommario):
Coolamon is a mid-season to late-season flowering F4-derived crossbred subterranean clover of var. subterraneum, developed by the collaborating organisations of the National Annual Pasture Legume Improvement Program. It is a replacement for Junee and has been selected for release on the basis of its greater herbage production and persistence, and its resistance to both known races of clover scorch. Coolamon is recommended for sowing in Western Australia, New South Wales, Victoria, South Australia and Queensland. It is best suited to well-drained, moderately acidic soils in areas with a growing season of 6.5–8 months that extends into November. Coolamon is best suited to phase farming and permanent pasture systems. It can also be used in cropping rotations, but at least 2 years of pasture are required between crops. Coolamon has been granted Plant Breeders Rights in Australia.
49
Clarke, C. J., G. W. Mauger, R. W. Bell e R. J. Hobbs CSIRO. "Computer modelling of the effect of revegetation strategies on salinity in the western wheatbelt of Western Australia 1. The impact of revegetation strategies". Soil Research 36, n. 1 (1998): 109. http://dx.doi.org/10.1071/s97006.
Testo completoAbstract (sommario):
The interactions between land, vegetation, and climate are highly complex and there are few demonstrations of the many potential combinations of treatments which could be used to combat dryland salinity. For this reason, computer simulations are used. This is the first of 2 papers that describe the results of computer modelling of revegetation strategies to reduce land and water salinisation in the western wheatbelt of Western Australia. A distributed parameter, physically based, cellular, 2-layer, mathematical model was used to simulate the effect of a variety of treatments. Modelling predicted that if current land use continues, 40% of the cleared area will become saline. Modelling replacement of the annual pasture with a deep-rooted perennial pasture or pristine native vegetation prevented the onset of salinity, but block or alley treatments always left a significant residual saline area and seepage even at the highest density of revegetation modelled. Combining remnant vegetation in pristine condition, 60-m-spaced tree belts and deep-rooted perennial pasture in mainly the upper mid-slope bays between tree belts reduced saline land to 10% of the cleared area and seepage volume to 30% of the untreated case. The second paper describes the impact of faults on treatment effectiveness.
50
Summers, RN, NR Guise, DD Smirk e KJ Summers. "Bauxite residue (red mud) improves pasture growth on sandy soils in Western Australia". Soil Research 34, n. 4 (1996): 569. http://dx.doi.org/10.1071/sr9960569.
Testo completoAbstract (sommario):
Red mud is a finely crushed, iron-rich, alkaline residue, obtained by digesting bauxite with caustic soda to remove the alumina. The remnant alkalinity of red mud is equivalent to 11% pure calcium carbonate. Phosphorus leaching from infertile sandy soils has resulted in eutrophication of estuaries and has caused algal blooms. Red mud has been shown to reduce leaching of phosphorus from sandy soil. This research was undertaken to determine the effect of red mud on pasture growth and uptake of heavy metals. Red mud, either untreated or treated with gypsum, was applied at rates of 0, 10, 20, 40, and 80 t/ha to a subterranean clover and ryegrass hay paddock. There were 3 replicates of each treatment and a completely randomised design was used. The experimental design was 5 rates of red mud x 2 untreated and treated with gypsum x 3 replicates, resulting in 30 plots. Plant growth, and nutrient and heavy metal composition of the plant tops, were measured. An application of 40 t/ha of red mud increased hay (mainly subterranean clover and ryegrass) production by 24% and increased soil pH in the top 10 cm by 1.0 unit from 3.5 (1 : 5 soil : 0.1 M CaCl2). The increase in production was probably because of the liming effect of the remnant alkali in the red mud, which may have potential as a replacement for crushed limestone. Sodium carbonate, the predominant alkali in red mud, is more soluble than calcium carbonate from crushed limestone and has the potential to change the pH of the soil more rapidly. The soil was top-dressed with red mud, without disturbing the existing pasture, resulting in changes to the pasture production and nutrient composition consistent with a change in soil pH throughout the rooting depth. If crushed limestone is not mixed into the soil it may take many years to increase the pH of the soil; however, this mixing results in extra cost from re-seeding and an initial depression in yield. Although much more red mud is needed than lime, the cost is comparable when the haulage distance is less than about 30 km. In previous trials, at red mud application rates > 500 t/ha, gypsum was mixed into the red mud to reduce salinity and pH. At these rates, the red mud had overwhelmed the buffering capacity of the soil. The gypsum reduced the pH by changing the sodium carbonate in the red mud to calcium carbonate, thus changing the pH from > 10 to about 8.5. However, amendment of the red mud with gypsum when applied at rates < 80 t/ha proved unnecessary in this experiment, probably because the proportion of soil was sufficient to alter the pH of the red mud. When red mud is applied to acidic infertile sands, manganese application as manganese sulfate may be necessary, because the rise in pH may rapidly induce manganese deficiency in plants. Care should be taken to monitor other nutrients which have their availability for plants affected by pH (e.g. copper, zinc, and molybdenum). Red mud did not elevate the concentrations of heavy metals in the soil, hay, or fresh plant tissue.