Letteratura scientifica selezionata sul tema "Victorian pastures"
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Articoli di riviste sul tema "Victorian pastures"
1
Robertson, S. M. "Mass to height relationships in annual pastures and prediction of sheep growth rates". Animal Production Science 54, n. 9 (2014): 1305. http://dx.doi.org/10.1071/an14072.
Testo completoAbstract (sommario):
The relationship between pasture height and mass influences the availability of pasture for grazing, and is important for predicting intake of pasture and liveweight change by sheep. The relationship between pasture mass and structure and sheep production is poorly defined for low-mass, clumpy pastures in low-rainfall regions. Between 2001 and 2004, 480 quadrats of pastures were measured in 23 paddocks throughout the Victorian Mallee. Pasture height was related to live mass for medic (linear; r2 = 0.70; P < 0.001) and grassy medic (asymptotic; r2 = 0.64; P < 0.001) pastures, and prediction of grassy medic pasture height was improved by inclusion of proportion live groundcover. During 2004, pasture dry matter accumulation and liveweight changes in sheep grazing annual pastures were measured and compared with predicted outputs from GrazFeed, a software model used to estimate feed intake and liveweight change in sheep. Improved predictions of liveweight gain in grazing sheep were obtained using measured height rather than the GrazFeed default height. The results show that the height to mass relationship of annual pastures in the Victorian Mallee differs between pasture types, between years, and may differ from other published relationships. This study provides information that may assist in the development of models of grazing systems.
2
Crawford, DM, TG Baker e J. Maheswaran. "Soil pH changes under Victorian pastures". Soil Research 32, n. 1 (1994): 105. http://dx.doi.org/10.1071/sr9940105.
Testo completoAbstract (sommario):
The severity and extent of surface soil acidification was assessed at 107 pasture sites across Victoria. At each site, soil samples (0.20 cm depth) were taken from the pasture area and an adjacent reference (undisturbed) area for analysis of soil pH (1:5 0.01 m CaCl2 or water). Acidification was evident in the 0.10 cm depth of sites with moderately and slightly acid (pH [water] 5.5-7) reference soils, while alkalinization was evident in the 0.20 cm depth of sites with strongly acid (pH [water] <5.5) reference soils. Causes of pH changes were not clearly evident from the relationships between site factors and changes in soil. It was evident that site factors were confounded since sites that had acidified often supported subterranean clover and had slightly to moderately acid reference soils, while sites which had alkalinized often supported white clover-based pastures under higher rainfall and had more acidic reference soils. An understanding of the causes of acidification in pasture-based agricultural ecosystems will only be gained through more fundamental studies at individual sites.
3
Reed, K. F. M., J. R. Walsh, P. A. Cross, N. M. McFarlane e M. A. Sprague. "Ryegrass endophyte (Neotyphodium lolii) alkaloids and mineral concentrations in perennial ryegrass (Lolium perenne) from southwest Victorian pasture". Australian Journal of Experimental Agriculture 44, n. 12 (2004): 1185. http://dx.doi.org/10.1071/ea03242.
Testo completoAbstract (sommario):
On all of 120 farms in south-west Victoria that were selected at random and sampled during autumn and winter over 2 years, perennial ryegrass was present in the pasture and tested positive for the presence of the naturally occurring ryegrass endophyte, Neotyphodium lolii (mean frequency 78%). Ryegrass staggers were reported on 33% (1999) and 43% (2000) of the surveyed farms. Clinically significant concentrations of lolitrem B were detected in perennial ryegrass samples with concentrations in the range 0–4.44 mg/kg. Concentration exceeded 1.8 mg/kg in 37% of pastures indicating an inherent, widespread problem for livestock farmers. Concentration was independent of endophyte frequency, pasture age, pasture height, annual rainfall and origin of sown cultivar. Ergovaline was detected in most of the perennial ryegrass samples with concentrations up to 3.90 mg/kg. In 1999, the mean concentration of ergovaline was 0.76 (± 0.70) mg/kg with 33% of pastures having a level >0.4 mg/kg, the level associated with heat stress in cattle. In 2000, sampling was carried out later in the year than for the 1999 survey and the mean concentration of ergovaline was 0.12 (± 0.10) mg/kg; 3% of samples exceeded 0.4 mg/kg. The mean concentration of peramine was 13.7 (± 6.6) mg/kg in the 1999 survey and 4.2 (± 5.1) mg/kg in the 2000 survey. Mineral analysis indicated that perennial ryegrass nutrition was inadequate with regard to phosphorous on 17% of the dairy pastures and on 37% of the sheep/beef pastures. Potassium was deficient in perennial ryegrass on 5 and 37% of dairy and sheep/beef pastures respectively. For perennial ryegrass in sheep/beef pastures, 25% were deficient in sulphur. For lactating cattle having only perennial ryegrass as a food source, phosphorous and copper concentrations in the grass were inadequate on 80% of the pastures. Calcium, zinc, magnesium, potassium and sulphur concentrations in perennial ryegrass were also inadequate on some pastures. However, with 1 exception, the ratio [K/(Ca+Mg) expressed as equivalents] was less than 2.2, the level associated with the development of hypomagnesemia. Hypomagnesemia (grass tetany) was therefore unlikely to be a major cause of the staggers syndrome. Lolitrem B was negatively correlated with grass potassium concentration (P<0.001). Ergovaline was negatively correlated with date of sampling (P<0.001). Peramine concentration was positively correlated with endophyte frequency, the potassium and sodium concentrations in perennial ryegrass and negatively correlated with date of sampling. The need for research on the economic impact and management of pasture contaminated with ryegrass endophyte toxins is discussed.
4
Trompf, J. P., e P. W. G. Sale. "The paired-paddock model as an agent for change on grazing properties across south-east Australia". Australian Journal of Experimental Agriculture 40, n. 4 (2000): 547. http://dx.doi.org/10.1071/ea00046.
Testo completoAbstract (sommario):
A detailed study was undertaken on the pasture management practices of 146 producers across south-east Australia who participated in the Grassland’s Productivity Program (GPP) for 3 years between 1993 and 1997. The GPP was an extension program to assist wool producers to develop skills and gain confidence in their ability to manage more productive pastures on their farms. The program consisted of 50 farmer groups (200 farmers participating) spread across the 4 states of South Australia, southern New South Wales, Victoria and Tasmania. Each farmer established paired-paddocks on their own property to compare productive pastures with existing pastures. Productive pastures involve increased rates of fertiliser on pastures containing productive species, with stocking rate adjusted to consume available pasture. After 3 years of involvement in the GPP, there was a whole-farm increase in P fertiliser use by 6.3 kg P/ha, stocking rates by 2.6 dse/ha and annual pasture resowing by 0.9% of the farm, when averaged across the 146 participants. The participants were applying the productive pasture technology to almost a third of their properties in 1997 and the intention was to increase this to over half of their properties by 2000. The participants also changed farm management practices as the program effectively developed management skills. There were increases in the ability to assess pasture quality and quantity, livestock by weighing or physical assessment, and the ability to calculate per hectare production and per hectare gross margins. A high proportion of GPP participants were soil testing (0.92) and spring lambing (0.72) at the completion of the program. The results indicated that the adoption of productive pastures was generally consistent across south-east Australia for pastoral producers who participated in this program, although south-west Victorian and south-east South Australian GPP participants did increase whole-farm P application by more than GPP participants from outside that region. The widespread change in farming practice was attributed to the additive and interactive effect of the paired-paddock comparison, the guidance provided by the facilitator, the group interaction and the skills training. Each of these components of the paired-paddock model combined to form an effective agent for change to increase pasture productivity on these grazing properties.
5
Harris, R. H., M. J. Unkovich e J. Humphris. "Mineral nitrogen supply from pastures to cereals in three northern Victorian environments". Australian Journal of Experimental Agriculture 46, n. 1 (2006): 59. http://dx.doi.org/10.1071/ea04177.
Testo completoAbstract (sommario):
An experiment at 3 sites (Birchip, Elmore and Speed) in the northern Victorian cropping belt compared dry matter (DM) production of short-term (2 year) pastures and their contributions to soil mineral nitrogen (N) and subsequent wheat and barley production. The pastures included different varieties of subterranean clover, annual medic and lucerne, and these were compared with ryegrass-dominant pasture, which represented the experimental control. More productive legume pastures generally resulted in greater accumulation of soil mineral N at sowing of the following cereal at both Elmore and Speed; however, at Birchip, soil mineral N remained high under all treatments. At Elmore and Speed, significant (P<0.10) positive relationships were observed between available N at sowing and subsequent wheat and barley production. Cereal grain yield at Birchip was not associated with available N at sowing. The quantities of soil mineral N available at sowing (152 kg/ha) of the cereals were in excess of crop demand at Birchip. At Elmore, the soil mineral N supply (83 kg/ha) was below that required for wheat and barley to reach their water-limited potential yield (20 kg grain/mm of growing season rainfall). However, at Speed, the supply of soil mineral N (63 kg/ha) was sufficient to achieve the water-limited potential grain yield and to produce malting-grade barley, but not sufficient to elevate wheat grain protein concentrations above 11.5%. In environments with low soil N levels, the amount of residual N following short-term pastures increased the availability of N to following cereals. Whether this is sufficient to satisfy subsequent crop demand is largely determined by water availability in the year of cropping. In cases where available N is already high, short-term pasture phases may have little effect on increasing crop production.
6
Robertson, S. M. "Predicting pasture and sheep production in the Victorian Mallee with the decision support tool, GrassGro". Australian Journal of Experimental Agriculture 46, n. 8 (2006): 1005. http://dx.doi.org/10.1071/ea04034.
Testo completoAbstract (sommario):
The GrassGro decision support tool was designed to quantify sheep and pasture production in response to management and climate variability in temperate Australia, and has been tested in temperate but not low-rainfall Australian conditions. Data from field experiments and from on-farm monitoring was used to test GrassGro predictions of annual and perennial pasture production, and sheep production at 4 locations throughout the Victorian Mallee, which is a low-rainfall area (275–375 mm annually). Predictions of long-term pasture production were then made. Predictions of the herbage biomass of annual pastures closely matched observed data for both a sandy loam (1991–2002 data) and a whole paddock (combining sandy loam and loam and sand) (2001–2002 data) soil type, at several locations across the Victorian Mallee. Linear regression between observed and simulated (April to September) data produced coefficients, significance and root mean square error of r2 = 0.81, P<0.001, 217 kg DM/ha, respectively, for sandy loam soil types and r2 = 0.94, P<0.001, 72 kg DM/ha, respectively, for whole paddock soil types. A series of simulations for individual years from 1970 to 2002 quantified the large impact of climate variability and demonstrated that seedbank and location, but not soil fertility, had a large influence on annual pasture production. However, GrassGro underestimated the production of the perennial pasture, lucerne (r2 = 0.2). GrassGro was also unable to adequately predict sheep production because it failed to take into account the sparse, clumpy structure of the low biomass pastures typical of this region. Methods to improve GrassGro were identified and included: (i) the need to adjust sheep intake from low biomass, sparse pastures, (ii) the ability to predict summer growing and autumn growing plant species, (iii) the ability to graze crop stubbles and (iv) refinements to the coefficients of equations used to model lucerne growth.
7
Elliott, D. E., e R. J. Abbott. "Nitrogen fertiliser use on rain-fed pasture in the Mt Lofty Ranges, SouthAustralia. 2. Responses of perennial grasses, Tama ryegrass, andsod-sown oats to nitrogen fertiliser and cutting frequency". Australian Journal of Experimental Agriculture 43, n. 6 (2003): 579. http://dx.doi.org/10.1071/ea01132.
Testo completoAbstract (sommario):
Two series of experiments were conducted in the Mt Lofty Ranges, South Australia, to examine, in a grass–subterranean clover pasture, the contribution of the companion grass to herbage mass and the responsiveness to the application of nitrogen (N) fertiliser. The first study examined the responsiveness, to a single rate of N, of grass–clover pastures containing either Tama ryegrass, sod-sown oats or 1 of 4 perennial grasses, viz. Victorian perennial ryegrass, Demeter fescue, Currie cocksfoot or Australian phalaris. These were compared in 2 experiments, under 3��different cutting frequencies at 3 periods during the growing season. In the other study, consisting of 12�experiments, the response to increasing rate of N fertiliser application of sod-sown oats or the existing pasture were compared over a 3-month period following N fertiliser application in autumn.In autumn and winter, all pastures responded significantly to N fertiliser, whereas in spring, the proportion of clover in each pasture and its growth determined whether or not there was a response to N fertiliser. Clover composition of pastures declined with N application, but clover was not eliminated from swards by application of 210 kg N/ha a year. In both series of experiments, pastures that established well with a high density of sod-sown oats out-yielded all other pastures in autumn and winter, whether the swards were unfertilised or received regular N fertiliser applications. In late winter, pastures sod-sown with Tama ryegrass yielded as well as the pasture sod-sown with oats, and enhanced spring growth significantly compared with perennial ryegrass. However, spring production of Tama ryegrass was poorer than that of perennial ryegrass, and overall no increase in annual production occurred. Of the perennial grasses, the highest yielding when N fertiliser was applied were Currie cocksfoot and perennial ryegrass (yielding in autumn), phalaris (winter), and perennial ryegrass and Demeter fescue (spring). Increased cutting frequency depressed the herbage mass response to N fertiliser following the initial application, but increased herbage N concentration of all pastures and also increased the final clover composition of N-fertilised pasture of 4�pasture types.
8
Reed, K. F. M., W. J. Mace, L. V. Walker e L. R. Fletcher. "Endophyte metabolites associated with perennial ryegrass toxicosis". Animal Production Science 56, n. 5 (2016): 895. http://dx.doi.org/10.1071/an14495.
Testo completoAbstract (sommario):
Perennial ryegrass (PRG) was analysed for alkaloids associated with the expression of perennial ryegrass endophyte toxicosis (PRGT) in south-east Australia. Over two seasons, the PRG cultivar Samson (‘high endophyte’, viz. naturally infected with a wild-type strain of Epichloë festucae var. lolii) was sampled on five occasions during November to May at four farms in Victoria and at Lincoln, New Zealand. Endophyte frequency in the populations was 77–100%. PRG was also sampled from 20 Victorian and Tasmanian farm pastures where stock were experiencing PRGT (endophyte infection frequencies of 87–100%). The Victorian summer of 2010–11 was atypically moist; pasture remained green. Lolitrem B was consistently high at Lincoln and 2–3 times that observed in Victorian samples of isogenetic PRG, or in PRG causing PRGT; it was the dominant toxin in 2011 with concentrations commonly exceeding the tolerance level of 1.8 mg/kg. In the following year, one with a more typical summer, ergovaline was the dominant toxin. Liquid Chromatography–Mass Spectrometry/Mass Spectrometry (LC-MS/MS) was carried out to determine indole diterpene intermediates in the lolitrem B biosynthesis pathway and for ergot alkaloid intermediates in the ergovaline pathway. The values for lolitrem B determined by LC-MS/MS correlated strongly with those obtained using high pressure liquid chromatography. In both Years 1 and 2, significantly higher expression was observed in the Lincoln relative to Victorian samples of PRG for paspaline, terpendole C, lolitrem E, lolitrem B and lolitrem F. For the ergot alkaloids, significant differences were not apparent between Victorian and Lincoln samples in Year 1. In Year 2, LC-MS/MS results showed ergovaline concentrations were greater in Victorian samples. In addition to endophyte-produced toxins, ergot alkaloids produced by Claviceps purpurea (ergotamine, ergocryptine and ergocornine) were detected in grass samples on 6/27 occasions. Some unidentified metabolites were noted in both Victorian and Lincoln samples. The effects of ingested vaso-constrictive ergot alkaloids combined with that of high solar radiation on ruminants’ heat load are considered most important with respect to the occasionally severe expression of PRGT in Australia.
9
Gardner, WK, RG Fawcett, GR Steed, JE Pratley, DM Whitfield, Hvan Rees e Rees H. Van. "Crop production on duplex soils in south-eastern Australia". Australian Journal of Experimental Agriculture 32, n. 7 (1992): 915. http://dx.doi.org/10.1071/ea9920915.
Testo completoAbstract (sommario):
The environment, duplex soil types and trends in crop production in South Australia, southern New South Wales, north-eastern and north-central Victoria, the southern Wimmera and the Victorian Western District are reviewed. In the latter 2 regions, pastoral industries dominate and crop production is curtailed by regular and severe soil waterlogging, except for limited areas of lower rainfall. Subsurface drainage can eliminate waterlogging, but is feasible only for the Western District where subsoils are sufficiently stable. The other regions all have a long history of soil degradation due to cropping practices, but these effects can now be minimised with the use of direct drilling and stubble retention cropping methods. A vigorous pasture ley phase is still considered necessary to maintain nitrogen levels and to restore soil structure to adequate levels for sustainable farming. Future productivity improvements will require increased root growth in the subsoils. Deep ripping, 'slotting' of gypsum, and crop species capable of opening up subsoils are techniques which may hold promise in this regard. The inclusion of lucerne, a perennial species, in annual pastures and intercropping at intervals is a technique being pioneered in north-central and western Victoria and may provide the best opportunity to crop duplex soils successfully without associated land degradation.
10
Lorimer, MS, e LA Douglas. "Effect of management practice on properties of a Victorian red-brown earth .1. Soil physical-properties". Soil Research 33, n. 5 (1995): 851. http://dx.doi.org/10.1071/sr9950851.
Testo completoAbstract (sommario):
The effects of five management practices (native forest, native pasture, Phalaris pasture, crop-pasture rotation, continuous cropping), that had been in place for 18 years, on some soil physical properties of a red-brown earth near Bendigo, Victoria, were studied. Particle size distribution, bulk density and hydraulic conductivity of soil in the A and B horizons at different, management sites were measured. Where cultivation had occurred, soil in the A horizon contained less silt and clay, and more fine sand and coarse sand. The bulk density of the A horizon of soil that had produced at least six wheat crops since 1969 was greater than that of soil used for pasture or forest, while the hydraulic conductivity of soil cropped every year since 1969 was much less than that of soil under native forest. Particle size distributions for soil from the B horizons at the five management sites were found to be similar. Where pastures and crops had been established, the hydraulic conductivity of the upper B horizon was lower, and the bulk density was higher, than that of soil in the native forest (Eucalyptus spp).
Tesi sul tema "Victorian pastures"
1
Riffkin, Penelope A., of Western Sydney Hawkesbury University e Faculty of Science and Technology. "An assessment of white clover nitrogen fixation in grazed dairy pastures of south-western Victoria". THESIS_FST_xxx_Riffkin_P.xml, 1999. http://handle.uws.edu.au:8081/1959.7/31.
Testo completoAbstract (sommario):
Australia is amongst the more efficient milk producers in the world.Milk production in the region of south-western Victoria relies mainly on rainfed white clover/perennial ryegrass pastures.As the demand for efficient and competitive milk production increases, the value of N2 fixation must be maximised. The objective of this thesis was to assess N2 fixation in grazed dairy pastures in south-western Victoria. Several tests and experiments were conducted and results noted. Studies revealed low white clover yields to be the major factor limiting N2 fixation in the region. For N2 fixation to have a significant impact on pasture quality and production, problems associated with legume persistence need to be addressed. Strategies may include the breeding of white clover cultivars with greater tolerance to water stress, improved winter production and increased competitiveness with companion species. Alternatively, the introduction of different legume species, better suited to the environment, may be appropriate. Where N2 fixation is unlikely to satisfy N demands, it may be necessary to introduce the strategic use of supplementary feeds or nitrogenous fertilisers. However, this would need to be carefully considered to ensure high input costs did not jeopardise the competitive advantage of low input pasture-based systemsMasters Thesis
2
Riffkin, Penelope A. "An assessment of white clover nitrogen fixation in grazed dairy pastures of south-western Victoria". Thesis, [Richmond, N.S.W.] : University of Western Sydney, Hawkesbury, 1999. http://handle.uws.edu.au:8081/1959.7/31.
Testo completoAbstract (sommario):
Australia is amongst the more efficient milk producers in the world.Milk production in the region of south-western Victoria relies mainly on rainfed white clover/perennial ryegrass pastures.As the demand for efficient and competitive milk production increases, the value of N2 fixation must be maximised. The objective of this thesis was to assess N2 fixation in grazed dairy pastures in south-western Victoria. Several tests and experiments were conducted and results noted. Studies revealed low white clover yields to be the major factor limiting N2 fixation in the region. For N2 fixation to have a significant impact on pasture quality and production, problems associated with legume persistence need to be addressed. Strategies may include the breeding of white clover cultivars with greater tolerance to water stress, improved winter production and increased competitiveness with companion species. Alternatively, the introduction of different legume species, better suited to the environment, may be appropriate. Where N2 fixation is unlikely to satisfy N demands, it may be necessary to introduce the strategic use of supplementary feeds or nitrogenous fertilisers. However, this would need to be carefully considered to ensure high input costs did not jeopardise the competitive advantage of low input pasture-based systems
3
Latta, Roy A. "Improving medic pastures in pasture-wheat rotations in the Mallee district of North-Western Victoria /". Title page, contents and abstract only, 1994. http://web4.library.adelaide.edu.au/theses/09A/09al364.pdf.
Testo completo
4
Riffkin, Penelope A. "An assessment of white clover nitrogen fixation in grazed dairy pastures of South-Western Victoria /". [Richmond, N.S.W.] : University of Western Sydney, Hawkesbury, 1999. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030528.152118/index.html.
Testo completo
5
Dyer, Rodd MacGregor. "Fire and vegetation management in pasture lands of the Victoria River District, Northern Territory /". St. Lucia, Qld, 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16803.pdf.
Testo completo
6
Latta, Roy A. (Roy Alexander). "Improving medic pastures in pasture-wheat rotations in the Mallee district of North-Western Victoria". 1994. http://web4.library.adelaide.edu.au/theses/09A/09al364.pdf.
Testo completo
7
Latta, Roy A. "Improving medic pastures in pasture-wheat rotations in the Mallee district of North-Western Victoria". Thesis, 1994. http://hdl.handle.net/2440/110234.
Testo completo
8
Cobiac, Michael D. "Predicting native pasture growth in the Victoria River district of the Northern Territory". 2006. http://hdl.handle.net/2440/36784.
Testo completoAbstract (sommario):
Pastoralism is the major economic activity in the Victoria River District (VRD), and is dependent on sustainable pasture use. Analysing grazing practices for sustainability requires knowledge of annual pasture production, but little quantitative data is available. A study was undertaken to develop the capacity for predicting native pasture growth in the VRD using systems modelling. Twenty one field sites were studied for two years using a standard methodology, and the Grass Production (GRASP) model was calibrated using this field data. End of growing season total standing dry matter (TSDM) was well predicted (mean = 2513kg/ha, r2(1:1) = 0.966, RMSE = 132kg/ha, and 98% of predictions within measurement variance). Developing generic parameters for common soil and pasture types allowed extrapolation of the model. Predictive skill declined when using generic parameters (r2(1:1) = -0.265, RMSE = 807kg/ha and 64% of predictions within measurement variance). However, observation and prediction means were very similar, indicating that generic parameters are suitable for broad scale applications, but site-specific parameters are necessary if a high degree of accuracy is required. Parameters controlling plant water uptake largely determine pasture growth in low rainfall years, while nitrogen uptake and dilution parameters limit growth in high rainfall years. Pasture growth is constrained by nitrogen supply in 91% of seasons in the northern VRD, and in 25% of seasons in the drier south. Example applications of the model were demonstrated. Current and expected future levels of pasture utilisation in the district were calculated, showing a current average of 16%, rising to an expected 20% in the next decade. These levels are within the safe utilisation rates recommended for the region. Economic analysis shows positive returns ($4.54 million per year) from pasture augmentation with introduced legumes if past problems with establishment and persistence can be overcome. Model performance would be improved by accounting for simultaneous wetting of the entire profile in cracking clay soils, calculating growth of perennial and annual pasture species separately, and simulating variation in nitrogen uptake and dilution between years. Incorporation of these processes must be balanced against the increased complexity of the model and the additional data required for calibration.Thesis(PhD)-- School of Agriculture, Food and Wine, 2006
9
Cobiac, Michael D. "Predicting native pasture growth in the Victoria River district of the Northern Territory". Thesis, 2006. http://hdl.handle.net/2440/36784.
Testo completoAbstract (sommario):
Pastoralism is the major economic activity in the Victoria River District (VRD), and is
dependent on sustainable pasture use. Analysing grazing practices for sustainability
requires knowledge of annual pasture production, but little quantitative data is available. A
study was undertaken to develop the capacity for predicting native pasture growth in the
VRD using systems modelling. Twenty one field sites were studied for two years using a
standard methodology, and the Grass Production (GRASP) model was calibrated using this
field data. End of growing season total standing dry matter (TSDM) was well predicted
(mean = 2513kg/ha, r2(1:1) = 0.966, RMSE = 132kg/ha, and 98% of predictions within
measurement variance).
Developing generic parameters for common soil and pasture types allowed extrapolation of
the model. Predictive skill declined when using generic parameters (r2(1:1) = -0.265,
RMSE = 807kg/ha and 64% of predictions within measurement variance). However,
observation and prediction means were very similar, indicating that generic parameters are
suitable for broad scale applications, but site-specific parameters are necessary if a high
degree of accuracy is required. Parameters controlling plant water uptake largely determine
pasture growth in low rainfall years, while nitrogen uptake and dilution parameters limit
growth in high rainfall years. Pasture growth is constrained by nitrogen supply in 91% of
seasons in the northern VRD, and in 25% of seasons in the drier south.
Example applications of the model were demonstrated. Current and expected future levels
of pasture utilisation in the district were calculated, showing a current average of 16%,
rising to an expected 20% in the next decade. These levels are within the safe utilisation
rates recommended for the region. Economic analysis shows positive returns ($4.54
million per year) from pasture augmentation with introduced legumes if past problems with
establishment and persistence can be overcome.
Model performance would be improved by accounting for simultaneous wetting of the
entire profile in cracking clay soils, calculating growth of perennial and annual pasture
species separately, and simulating variation in nitrogen uptake and dilution between years.
Incorporation of these processes must be balanced against the increased complexity of the
model and the additional data required for calibration.Thesis(PhD)-- School of Agriculture, Food and Wine, 2006
Libri sul tema "Victorian pastures"
1
Sidney, Samuel. Three Colonies of Australia : New South Wales, Victoria, South Australia: Their Pastures, Copper Mines, & Gold Fields. Creative Media Partners, LLC, 2018.
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2
The Three Colonies of Australia : New South Wales, Victoria, South Australia: Their Pastures, Copper Mines, & Gold Fields. Franklin Classics, 2018.
Cerca il testo completoCapitoli di libri sul tema "Victorian pastures"
1
Crawford, D. M., C. D. Parnell e J. Maheswaran. "Acidification of sub-surface soils under pastures in Victoria, Australia". In Plant-Soil Interactions at Low pH: Principles and Management, 467–71. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0221-6_71.
Testo completo
2
Ridley, A. M., e D. R. Coventry. "Soil acidification under pastures of north-eastern Victoria five years after liming". In Plant-Soil Interactions at Low pH: Principles and Management, 473–77. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0221-6_72.
Testo completo
3
Beinart, William, e Lotte Hughes. "Imperial Travellers". In Environment and Empire. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780199260317.003.0010.
Testo completoAbstract (sommario):
In a global maritime empire, travel was intrinsic. As sailors and slavers, traders and hunters, Europeans traversed colonized space and literacy gave them the power to record what they saw and found. In their mapping and classification of lands and peoples, many of these travellers helped to commodify and package the resources of empire. In their fulsome descriptions of the riches of overseas territories, they made these lands and all that they contained desirable to prospective hunters, settlers, speculators, and administrators. The direct uses that imperial powers made of traveller’s accounts were hinted at in 1887 by British explorer and geologist Joseph Thomson, in a note to the second edition of his best-selling Through Masai Land. “Then [1885] Masai land was for the first time made known to the world; now it has come within the “sphere of British influence”—a delicate way, I suppose, of saying that it now practically forms a part of our imperial possessions.’ In fact British East Africa, of which Maasailand formed a large part, was not established for another eight years, in 1895. But Thomson anticipated accurately: having ‘discovered’ and mapped a direct route from the coast to Lake Victoria, which cut right across Maasailand to Uganda, and described the rich pickings (including fertile land, valuable pastures, water sources, timber, and game animals) that lay along the route, he had paved the way for European trade and takeover. Sir John Kirk, British agent and consul at Zanzibar, wrote that Thomson’s ‘admirable description is the only reliable one we yet possess of the region thus secured to us, if we choose to avail ourselves of the opportunity’. Britain, anxious about Germany’s competitive ambitions, duly took it. From the mid-eighteenth century a particular kind of traveller did more than most to promote the natural potential of empire: those who combined touring with botany and other scientific, or quasi-scientific, enquiries. The avid collection of specimens—from fauna and flora through, in some cases, to human body parts—had become an adjunct to the European adventurer’s taxonomy of the natural world. Since European expansion coincided with the development of print, as illustrated in our chapter on hunting, the production and publication of texts became a by-product of travel.