Articoli di riviste: "Pastures South Australia Field experiments"

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Li, G. D., K. R. Helyar, C. M. Evans, M. C. Wilson, L. J. C. Castleman, R. P. Fisher, B. R. Cullis e M. K. Conyers. "Effects of lime on the botanical composition of pasture over nine years in a field experiment on the south-western slopes of New South Wales". Australian Journal of Experimental Agriculture 43, n. 1 (2003): 61. http://dx.doi.org/10.1071/ea01194.

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Two permanent pastures (annual pasture v. perennial pasture) were established in 1992 as part of the long-term field experiment, MASTER — Managing Acid Soils Through Efficient Rotations. The primary objective of the experiment was to develop an agricultural system that is economically viable and environmentally sustainable on the highly acidic soils in south-eastern Australia. This paper reports on the effects of lime on the botanical composition changes of annual and perennial pastures over 9 years. In general, lime increased the proportion of the desirable species, such as phalaris (Phalaris aquatica) in perennial pasture and subterranean clover (Trifolium subterraneum) in annual pastures, and decreased the proportion of the undesirable species, such as Vulpia spp., in both annual and perennial pastures, ultimately improving the quality of feed-on-offer to animals. As a result, the limed pastures carried 24% more sheep than the unlimed pastures, while maintaining individual animal performance similar for both limed and unlimed pastures. The phalaris-based perennial pasture was more stable in terms of maintaining the sown species than the annual pasture. Lime improved the persistence of phalaris and the longevity of the phalaris-based pasture should be at least 10 years. Lime changed the direction of plant succession of annual pastures. Without lime, Vulpia spp. gradually became more dominant while ryegrass and subterranean clover became less dominant in annual pastures. With lime, barley grass (Hordeum leporinum) gradually invaded the sward at the expense of ryegrass, thus reducing the benefits of lime, but this effect was less for the perennial pastures than for annual pastures. Liming perennial pastures should be more beneficial than liming annual pastures because of the beneficial effects on pasture composition. In addition, previously published work reported that liming perennial pastures improved sustainability through better use of water and nitrogen.

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Bolan, NS, RE White e MJ Hedley. "A review of the use of phosphate rocks as fertilizers for direct application in Australia and New Zealand." Australian Journal of Experimental Agriculture 30, n. 2 (1990): 297. http://dx.doi.org/10.1071/ea9900297.

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Field trials in New Zealand have shown that reactive phosphate rocks (RPRs) can be as effective as soluble P fertilisers, per kg of P applied, on permanent pastures that have a soil pH<6.0 (in water) and a mean annual rainfall >800 mm. Whereas RPRs such as North Carolina, Sechura, Gafsa and Chatham Rise have been evaluated on permanent pastures in New Zealand, most Australian field trials have examined unreactive PRs such as Christmas Island A and C grade, Nauru and Duchess, using annual plant species. Only in recent experiments has an RPR, North Carolina, been examined. Except on the highly leached sands in southern and south-western Australia, both reactive and unreactive PRs have shown a low effectiveness relative to superphosphate. In addition to chemical reactivity, other factors may contribute to the difference in the observed agronomic effectiveness of PRs in Australia and New Zealand. Generally, PRs have been evaluated on soils of lower pH, higher pH buffering capacity (as measured by titratable acidity) and higher P status in New Zealand than in Australia. Rainfall is more evenly distributed throughout the year on New Zealand pastures than in Australia where the soil surface dries out between rainfall events. Dry conditions reduce the rate at which soil acid diffuses to a PR granule and dissolution products diffuse away. Even when pH and soil moisture are favourable, the release of P from PR is slow and more suited to permanent pasture (i.e. the conditions usually used to evaluate PRs in New Zealand) than to the annual pastures or crops used in most Australian trials. Based on the criteria of soil pH<6.0 and mean annual rainfall >800 mm, it is estimated that the potentially suitable area for RPRs on pasture in New Zealand is about 8 million ha. Extending this analysis to Australia, but excluding the seasonal rainfall areas of northern and south-western Australia, the potentially suitable area is about 13 million ha. In New Zealand, many of the soils in the North and South Islands satisfy both the pH and rainfall criteria. However, suitable areas in Australia are confined mainly to the coastal and tableland areas of New South Wales and eastern Victoria, and within these areas the actual effectiveness of RPR will depend markedly on soil management and the distribution of annual rainfall. Further research on RPR use should be focused on these areas.

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Latta, R. A., e A. Lyons. "The performance of lucerne - wheat rotations on Western Australian duplex soils". Australian Journal of Agricultural Research 57, n. 3 (2006): 335. http://dx.doi.org/10.1071/ar04016.

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In field experiments on duplex soils in the south-eastern and central Western Australian wheatbelt, lucerne (Medicago sativa L.) was compared with subterranean clover (Trifolium subterraneum L.) in pasture–crop rotations. Comparative pasture plant densities and biomass, soil water content, available soil nitrogen, wheat grain yield, and protein content were measured during 2 and 3 years of pasture followed by 2 and 1 year of wheat, respectively. Lucerne densities declined by 60–90% over the 3-year pasture phase but produced up to 3 times more total annual biomass than weed-dominant annual pastures and similar total annual biomass when annual pastures were legume dominant. Lower soil water contents were measured under lucerne than under annual pastures from 6 months after establishment, with deficits up to 60 mm in the 0–1.6 m soil profile. However, significant rain events and volunteer perennial weeds periodically negated comparative deficits. Wheat yields were lower following lucerne (1.3 t/ha) than following an annual pasture (1.8 t/ha) in a low-rainfall season, higher (3.7 v. 2.9 t/ha) in a high-rainfall season, and much higher when the previous annual pastures were grass dominant (3.4 v. 1.5 t/ha). Grain protein contents were 1–2% higher in response to the lucerne pasture phase. Overcropping wheat into a lucerne pasture of 19 plants/m2 reduced wheat grain yields, but a lucerne density of 4 plants/m2 reduced yields only where rainfall was low. The study has shown that lucerne–wheat rotations provide a productive farming system option on duplex, sodic soils in both the south-eastern and central cropping regions of Western Australia. This was most evident in seasons of above-average summer and growing-season rainfall and when compared with grass-dominant annual pastures.

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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.

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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.

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Reuter, DJ, CB Dyson, DE Elliott, DC Lewis e CL Rudd. "An appraisal of soil phosphorus testing data for crops and pastures in South Australia". Australian Journal of Experimental Agriculture 35, n. 7 (1995): 979. http://dx.doi.org/10.1071/ea9950979.

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Data from more than 580 field experiments conducted in South Australia over the past 30 years have been re-examined to estimate extractable soil phosphorus (P) levels related to 90% maximum yield (C90) for 7 crop species (wheat, barley, oilseed rape, sunflower, field peas, faba beans, potato) and 3 types of legume-based pasture (subterranean clover, strawberry clover, annual medics). Data from both single-year and longer term experiments were evaluated. The C90 value for each species was derived from the relationship between proportional yield responsiveness to applied P fertiliser rates (determined as grain yield in crops and herbage yield in ungrazed pastures) and extractable P concentrations in surface soils sampled before sowing. Most data assessments involved the Colwell soil P test and soils sampled in autumn to 10 cm depth. When all data for a species were considered together, the relationship between proportional yield response to applied P and soil P status was typically variable, particularly where Colwell soil P concentration was around C90. When data could be grouped according to common soil types, soil surface texture, or P sorption indices (selected sites), better relationships were discerned. From such segregated data sets, different C90 estimates were derived for either different soil types or soil properties. We recommend that site descriptors associated with the supply of soil P to plant roots be determined as a matter of course in future P fertiliser experiments in South Australia. Given the above, we also contend that the Colwell soil P test is reasonably robust for estimating P fertiliser requirements for the diverse range of soils in the agricultural regions of the State. In medium- and longer term experiments, changes in Colwell soil P concentration were measured in the absence or presence of newly applied P fertiliser. The rate of change (mg soil P/kg per kg applied P/ha) appeared to vary with soil type (or soil properties) and, perhaps, cropping frequency. Relatively minor changes in soil P status were observed due to different tillage practices. In developing P fertiliser budgets, we conclude that a major knowledge gap exists for estimating the residual effectiveness of P fertiliser applied to diverse soil types under a wide range of South Australian farming systems.

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Bolland, M. D. A., J. S. Yeates e M. F. Clarke. "Single and coastal superphosphates are equally effective as sulfur fertilisers for subterranean clover on very sandy soils in high rainfall areas of south-western Australia". Australian Journal of Experimental Agriculture 43, n. 9 (2003): 1117. http://dx.doi.org/10.1071/ea02168.

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To reduce leaching of phosphorus (P) from fertilised pastures to shallow estuaries in the high rainfall (>800 mm annual average) areas of south-western Australia, and to supply extra sulfur (S) for subterranean clover (Trifolium subterraneum L.) in pasture, 'coastal superphosphate' was developed as a possible alternative P and S fertiliser to single superphosphate. Coastal superphosphate is made by adding phosphate rock and elemental S to single superphosphate as it comes out of the den before granulation. It has about 3 times more sulfur (S) and one-third the water-soluble P content than single superphosphate. Four long-term (5-year) field experiments were conducted in south-western Australia to compare the effectiveness of single and coastal superphosphate as S fertilisers for subterranean clover pasture grown on very sandy soils that are frequently S deficient after July each year due to leaching of S from soil. Seven different amounts of S were applied as fertiliser annually. Fertiliser effectiveness was assessed from clover herbage yield and S concentration in dried herbage. Fertiliser nitrogen was not applied in these experiments as this was the normal practice for pastures in the region when the research was conducted.Both coastal and single superphosphates were equally effective per unit of applied S for producing dried clover herbage and increasing S concentration in herbage. Previous research on very sandy soils in the region had shown that coastal superphosphate was equally or more effective per unit of applied P for production of subterranean clover herbage. It is, therefore, concluded that coastal superphosphate is a suitable alternative S and P fertiliser for clover pastures on very sandy soils in the region. The concentration of S in dried clover herbage that was related to 90% of the maximum yield (critical S) was about 0.20–0.35% S during August (before flowering) and 0.15–0.20% S during October (after flowering).

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Bolland, M. D. A., D. G. Allen e Z. Rengel. "Response of annual pastures to applications of limestone in the high rainfall areas of south-western Australia". Australian Journal of Experimental Agriculture 42, n. 7 (2002): 925. http://dx.doi.org/10.1071/ea01169.

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The yield response of long-term pastures growing on acidified soil to applications of limestone (0, 2.5, 5.0, 7.5 and 10.0 t/ha with adequate magnesium fertiliser, and 0 and 5 t/ha with no magnesium fertiliser) was measured in 5 field experiments on different representative soils of the high rainfall areas of south-western Australia. After application, limestone was incorporated 1 cm deep in 3 experiments, 3 cm deep in 1 experiment, and 7 cm in another experiment. The pastures comprised subterranean clover (Trifolium subterraneum), and annual and Italian ryegrass (Lolium rigidum and L. multiflorum), the dominant species found in intensively grazed dairy and beef pastures of the region. Yields were measured when ryegrass plants had 3 leaves per tiller, which is when pastures in the region are grazed to maximise utilisation by cattle.Subsoil acidity was a problem at 4 of the 5 sites, and was so severe at 1 site that, despite having the lowest soil pH to 50 cm depth, there was no yield response to limestone incorporated to 3 cm deep. Applications of fertiliser magnesium had no significant effect on pasture production, soil pH, aluminium and manganese, or concentration of magnesium in dried herbage in any of the 5 experiments. Increasing amounts of limestone consistently: (i) increased soil pH, by between 1–2 pH units in the top 5 cm of soil, and 0.5–1.0 of a pH unit in the 5–10 cm soil profile; and (ii) decreased, by up to 84–98%, the amount of exchangeable aluminium in the 0–5 and 5–10 cm soil profiles. During 3 years (1998–2000) there were: (i) no yield responses to limestone for a total of 9 assessments on a sand, or 11 assessments on a sandy gravel; (ii) 2 significant (P<0.05) yield responses to limestone, from a total of 8 assessments on a loamy clay and from 9 assessments on a loam; (iii) 9 significant yield responses from a total of 13 assessments on a sandy loam (2 from 5 assessments in 1998, 3 from 4 assessments in 1999, and all 4 assessments in 2000). The sandy loam had the largest amount of exchangeable aluminium in the top 5 cm of soil [about 1.6 cmol(+)/kg, accounting for 35% of the exchangeable cations]. Increasing limestone applications did not induce deficiency or toxicity of any nutrient elements in subterranean clover or ryegrass dried herbage and, for dried herbage of bulk samples of both species, had no effect on dry matter digestibility, metabolisable energy and concentration of crude protein.

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Hume, D. E., e J. C. Sewell. "Agronomic advantages conferred by endophyte infection of perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinacea Schreb.) in Australia". Crop and Pasture Science 65, n. 8 (2014): 747. http://dx.doi.org/10.1071/cp13383.

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Perennial ryegrass and tall fescue are key grasses of sown pastures in the high-rainfall zone of south-eastern Australia. Ryegrass in naturalised pastures, and in sown seed, is widely infected with Neotyphodium fungal endophytes, with toxic endophyte strains occasionally causing toxicosis in livestock. Endophyte infection is also beneficial in sown grasslands, assisting ryegrass hosts to overcome biotic stresses, and tall fescue hosts to overcome biotic and abiotic stresses. We review the literature for Australia and present new data, to examine the agronomic effects of endophyte. Frequency of endophyte infection in old, perennial ryegrass pastures and ecotype-based cultivars is high and, in all pastures, increases with time, providing evidence for endophyte-infected plants having an agronomic advantage over endophyte-free plants. Within a cultivar, agronomic field experiments have compared endophyte-infected with endophyte-free swards. Endophyte significantly improved ryegrass establishment in seven of 19 measurements taken from 12 trials. In mature ryegrass pastures, over half of the experiments found advantages to endophyte infection. Tall fescues infected with a selected endophyte (‘AR542’) had improved agronomic performance relative to endophyte-free in a majority of experiments, and on occasions, the endophyte was essential for tall fescue persistence. Cultivar × endophyte interactions occurred but were inconsistent. In high-stress environments, endophyte was more important for agronomic performance than difference between cultivars. The relative importance of cultivar and endophyte is discussed, with elite cultivars that are adapted to the region and are infected with elite endophytes being the best avenue to capture the benefits and minimise detrimental endophyte effects on livestock. The major drivers are likely to be insect pests and drought, but evidence is limited.

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Bolland, M. D. A., J. S. Yeates, B. J. Codling e M. F. Clarke. "Tissue testing to assess the sulfur requirements of subterranean clover on very sandy soils in high rainfall areas of south-western Australia". Australian Journal of Experimental Agriculture 43, n. 11 (2003): 1311. http://dx.doi.org/10.1071/ea02164.

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Tissue testing was studied in field experiments between 1979 and 1985 to predict when sulfur (S) fertiliser was required for pastures in high rainfall (>650 mm annual average) areas of south-western Australia. The pastures comprised about half subterranean clover and annual ryegrass (Lolium rigidum Gaud.), the major pasture species in the region. Tissue testing was done for each species, using: (i) whole shoots, the present method used by commercial laboratories in Western Australia; (ii) youngest open leaves (legumes, YOLs) or youngest expanded blades (grass, YEBs); (iii) old leaves and blades (leaves that were not YOLs or YEBs); and (iv) stems (left after removal of YOLs, YEBs, old leaves and blades). Dried tissue was measured for total S, sulfate S, the total nitrogen : total S ratio and the sulfate S : total S ratio. For each pasture species, tissue test values were related to yield of dried herbage of that species measured for plants cut at ground level. Fertiliser nitrogen was not applied in the experiments.Annual ryegrass showed no significant yield responses to applied fertiliser S for all harvests in all experiments. Subterranean clover showed significant yield responses for most harvests of all experiments. At each site in each year, yield responses to applied S tended to become larger as the growing season progressed. For subterranean clover critical S values related to 90% of the maximum (relative) yield varied for different harvests of the same experiment within and between years, and for different experiments in the same and different years. As determined from all data, critical S values were similar for all plant parts (whole shoots, YOLs, old tissue, stems), with no consistent, systematic trend with plant age, and were: total S, range 0.10–0.30% S, mean 0.23%; sulfate S, range 0.01–0.14%, mean 0.04%; total N : total S ratio, range 11–30, mean 19; sulfate S : total S ratio, range 0.01–0.48, mean 0.27. The exception was that total S was lower for clover stems, the range being 0.06–0.20%, and mean 0.13%. Therefore, % total S in clover shoots can continue to be used as an indicator of sulfur deficiency in subterranean clover in the region.

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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.

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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.

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Badgery, W. B., e D. L. Michalk. "Synthesis of system outcomes for a grazing-management experiment in temperate native pastures". Animal Production Science 57, n. 9 (2017): 1869. http://dx.doi.org/10.1071/an16599.

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Increasing the intensity of grazing management from continuous grazing or set-stocking to intensive rotational grazing has been proposed as a way of improving the profitability and environmental outcomes for native pasture-based grazing systems in the high-rainfall zone (HRZ) of southern Australia. The present paper synthesised the results and outcomes of eight papers covering different aspects of a grazing-system study investigating the intensity of grazing management at Panuara (33°27ʹS, 148°56ʹE), 25 km south-west of Orange, New South Wales. The systems analysis covered soils and soil water, pastures, animal production, profitability and business risk by using a combination of field experiments and biophysical modelling. The experimental approach, engagement with stakeholders and the potential impact of the research outcomes are discussed; as are the future directions for grazing system research. Increasing the intensity of grazing management from a 1- to a 20-paddock system resulted in a 21% higher pasture growth, 22% higher stocking rate and 20% higher lamb production per hectare. However, modelling demonstrated that seasonal variability had a greater impact on profitability than did the management system, and whole-farm profitability of the 20-paddock system was lower than that of the 1- and 4-paddock systems due to higher infrastructure costs. Pasture stability was associated with a high perennial grass content (>70%), and a stocking rate of 4.2 ewes/ha for continuous grazing or 5.3 ewes/ha for intensive rotational grazing limited the potential for degradation events. Advantages were identified in fencing and managing production zones, with different production potential within a farm, to improve utilisation across the landscape and efficiency of fertiliser use. The farming-system approach successfully integrated field research with pre- and post-experimental modelling, and with strategic input from an advisory group containing farmers, researchers and advisors, to develop a full understanding of the impact, at a system level, of increasing the intensity of grazing management in the HRZ.

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Li, Guangdi D., Richard C. Hayes, Jeff I. McCormick, Matthew J. Gardner, Graeme A. Sandral e Brian S. Dear. "Time of sowing and the presence of a cover-crop determine the productivity and persistence of perennial pastures in mixed farming systems". Crop and Pasture Science 65, n. 10 (2014): 988. http://dx.doi.org/10.1071/cp13447.

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Incorporation of perennial pastures into cropping rotations can improve whole-farm productivity, profitability and sustainability of mixed farming systems in southern Australia. However, success in establishing perennial pastures depends on choice of species, time of sowing, method of establishment, seasonal conditions, and whether sowing is under a cover-crop. Field experiments were sown from 2008 to 2010 to determine effects of sowing time and the presence of a cover-crop on the performance of four perennial pasture species, lucerne (Medicago sativa L.), chicory (Cichorium intybus L.), phalaris (Phalaris aquatica L.) and cocksfoot (Dactylis glomerata L.), at Yerong Creek, New South Wales (NSW). Results showed that lucerne was the most productive pasture, followed by chicory and phalaris, with cocksfoot being the poorest performer. Under favourable seasonal conditions, lucerne and chicory pastures produced 29.3 and 25.0 t ha–1 of total dry matter (DM), comprising 71% and 52%, respectively, of sown perennial species in the sward in their second growing season, when sown in autumn. Spring-sown pastures produced 24.6 and 18.3 t ha–1 of total DM in the second season, with 55% and 47% of sown species in the sward being lucerne and chicory, respectively. However, spring-sown pastures contained a very low proportion of subterranean clover (Trifolium subterraneum L.) in the sward in the first 2 years, despite efforts to broadcast seeds at the break of season in the following year. It is recommended that non-legume perennial species, such as chicory and phalaris, be sown in autumn with companion annual legumes until methods are developed and tested to establish annual legumes reliably in spring. However, lucerne can be established in autumn or spring because it can fix its own nitrogen and is not reliant on a companion legume. Cocksfoot cv. Kasbah, in general, appears less suitable than the other perennial species for this medium-rainfall environment in southern NSW. Our study showed that pastures sown without a cover-crop had the most reliable establishment, whereas pastures sown with a cover-crop in a dry year had poor establishment or total failure, as well as a significant reduction of grain yield from the cover-crop. In a wet year, pastures established satisfactorily under a cover-crop; however, growth of the cover-crop still suppressed pasture DM production in subsequent years. Research is under way to model our data to determine the likely financial implications of establishing perennial pastures under cover-crops.

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Moore, A. D., P. J. Vickery, M. J. Hill, J. R. Donnelly e G. E. Donald. "Combining satellite data with a simulation model to describe spatial variability in pasture growth at a farm scale". Australian Journal of Experimental Agriculture 39, n. 3 (1999): 285. http://dx.doi.org/10.1071/ea98109.

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Practical application of simulation modelling as a decision aid for grazing system management usually involves an assumption of uniformity of model inputs over a farm paddock or property. In reality, paddocks and farms display high spatial variability in model inputs. There is considerable interest in assessing the significance of this spatial variablity for anmal production and enterprise profitability. This study seeks to demonstrate the use of spatial data with the GRAZPLAN pasture model to provide estimates of annual net primary production from pastures at a farm scale on the Northern Tablelands of New South Wales, Australia. The GRAZPLAN pasture model was validated against data from 2 separate field experiments for a typical improved pasture based on Phalaris aquatica from 1968 to 1972. A spatial coverage, classifying paddocks into 9 pasture types based on a botanical survey, was used to define the pasture parameter sets used in simulations. A Landsat TM satellite image classified to give 3 pasture growth status classes was used to define within-paddock levels of a fertility index used in the simulation model. Simulations over 1975–94 were conducted for all combinations of pasture types and fertility scalar values using climate data for the CSIRO Pastoral Research Laboratory near Armidale. Simulation output was written to a lookup table and imported into a PC-based geographic information system. The spatial data layers were combined to form a display template representing spatial variation in pasture type, pasture condition and fertility. The spatial template was reclassified using the lookup tables to create maps of annual net primary production from pastures. Spatial variability in simulated annual net primary production was greater for the paddocks with diverse mixtures of sown and native species than for the more uniform highly improved or pure native pastures. The difference in response to rainfall of simulated net primary production was greater between different pastures types than between different levels of the fertility index. The resulting maps provide a demonstration of the way in which satellite imagery and other data can be interfaced with a decision support system to provide information for use in precision management of grazing systems. Implementation of such methods as a management tool will depend on development of quantitative spatial data layers which provide accurate and repeatable initial conditions and parameter values for simulation models.

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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.

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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.

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15

Bolland, M. D. A., W. J. Cox e B. J. Codling. "Soil and tissue tests to predict pasture yield responses to applications of potassium fertiliser in high-rainfall areas of south-western Australia". Australian Journal of Experimental Agriculture 42, n. 2 (2002): 149. http://dx.doi.org/10.1071/ea01060.

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Abstract (sommario):

Dairy and beef pastures in the high (>800 mm annual average) rainfall areas of south-western Australia, based on subterranean clover (Trifolium subterraneum) and annual ryegrass (Lolium rigidum), grow on acidic to neutral deep (>40 cm) sands, up to 40 cm sand over loam or clay, or where loam or clay occur at the surface. Potassium deficiency is common, particularly for the sandy soils, requiring regular applications of fertiliser potassium for profitable pasture production. A large study was undertaken to assess 6 soil-test procedures, and tissue testing of dried herbage, as predictors of when fertiliser potassium was required for these pastures. The 100 field experiments, each conducted for 1 year, measured dried-herbage production separately for clover and ryegrass in response to applied fertiliser potassium (potassium chloride). Significant (P<0.05) increases in yield to applied potassium (yield response) were obtained in 42 experiments for clover and 6 experiments for ryegrass, indicating that grass roots were more able to access potassium from the soil than clover roots. When percentage of the maximum (relative) yield was related to soil-test potassium values for the top 10 cm of soil, the best relationships were obtained for the exchangeable (1 mol/L NH4Cl) and Colwell (0.5 mol/L NaHCO3-extracted) soil-test procedures for potassium. Both procedures accounted for about 42% of the variation for clover, 15% for ryegrass, and 32% for clover + grass. The Colwell procedure for the top 10 cm of soil is now the standard soil-test method for potassium used in Western Australia. No increases in clover yields to applied potassium were obtained for Colwell potassium at >100 mg/kg soil. There was always a clover-yield increase to applied potassium for Colwell potassium at <30 mg/kg soil. Corresponding potassium concentrations for ryegrass were >50 and <30 mg/kg soil. At potassium concentrations 30–100 mg/kg soil for clover and 30–50 mg/kg soil for ryegrass, the Colwell procedure did not reliably predict yield response, because from nil to large yield responses to applied potassium occurred. The Colwell procedure appears to extract the most labile potassium in the soil, including soluble potassium in soil solution and potassium balancing negative charge sites on soil constituents. In some soils, Colwell potassium was low indicating deficiency, yet plant roots may have accessed potassum deeper in the soil profile. Where the Colwell procedure does not reliably predict soil potassium status, tissue testing may help. The relationship between relative yield and tissue-test potassium varied markedly for different harvests in each year of the experiments, and for different experiments. For clover, the concentration of potassium in dried herbage that was related to 90% of the maximum, potassium non-limiting yield (critical potassium) was at the concentration of about 15 g/kg dried herbage for plants up to 8 weeks old, and at <10 g/kg dried herbage for plants older than 10–12 weeks. For ryegrass, there were insufficient data to provide reliable estimates of critical potassium.

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16

Black, I. D., R. N. Pederson, A. Flynn, M. Moerkerk, C. B. Dyson, R. Kookana e N. Wilhelm. "Mobility and persistence of three sulfonylurea herbicides in alkaline cropping soils of south-eastern Australia". Australian Journal of Experimental Agriculture 39, n. 4 (1999): 465. http://dx.doi.org/10.1071/ea98097.

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Abstract (sommario):

Biologically active residues of the herbicides metsulfuron-methyl, chlorsulfuron and triasulfuron were estimated with field pea bioassays in soil samples to 80 cm depth from 4 field trials in south-eastern Australia situated on neutral to highly alkaline soil. Residues were both mobile and persistent at low levels. Leaching occurred beyond the lowest sampling depth during the winter–spring growing season. Metsulfuron-methyl was the most mobile of the 3 herbicides. Plant-back experiments involving susceptible crop and pasture species on 2 of the sites showed that the rates of decline of these residues in the sampling zone were slower than might be inferred from label plant-back recommendations in 1 of 2 seasons.

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17

Thompson, R. B., e I. R. P. Fillery. "Fate of urea nitrogen in sheep urine applied to soil at different times of the year in the pasture - wheat rotation in south Western Australia". Australian Journal of Agricultural Research 49, n. 3 (1998): 495. http://dx.doi.org/10.1071/a97097.

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Abstract (sommario):

Sheep urine labelled with 15N-urea was applied toconfined micro-plots at different times of the year to follow the fate of ureaN in urine in the grazed pasture-wheat rotation in south Western Australia.Three field experiments were conducted on the same site on a loamy sand.Applications were made either to pasture residues (Expts 1 and 2) which weresubsequently sown to wheat, orto growing pasture in winter-spring, (Expt 3).In Expt 1, urine was applied in November 1990 (9·8 gN/m2) and April 1991 (46·1 gN/m2). From both applications, losses of15N attributed to NH3volatilisation were c. 50% within 2 weeks of application. Another10% loss was attributed toNO-3 leaching during the followinggrowing season and 15% was recovered by the wheat crop. In Expt 2,urine was applied in October 1991 (4·6 gN/m2), January 1992 (15·6 gN/m2), and March 1992 (13·6 gN/m2). Attributed NH3 losseswithin 2 weeks, in terms of 15N-urea applied, were40% (October and January urine) and 30% (March urine) andNO-3 leaching losses were estimated to be 20% forthe 3 applications. Recoveries in wheat (November 1992) were 4, 7, and12% of 15N applied in the October, January, andMarch urine applications. In Expt 3, urine was applied in August 1992(12·3 g N/m2) and September 1992 (25·9g N/m2). Attributed NH3 losseswere 10% of applied 15N for the August and30% for the September application. Plant uptake of15N was rapid and by mid October was 42% from theAugust application and 47% from the September application. Recovery of15N in soil organic N was generally 17-25% whenurine was applied to pasture residues and bare soil,and 21-37% whenurine was applied to growing pasture. It is suggested thatNH3 volatilisation was the predominant N loss mechanism.The amount of NO-3 leached wasprimarily influenced by summer rainfall, the length of time urine-N was insoil before the onset of winter rainfall, and the distributionof winterrainfall. Little of the 15N-labelled urine was eitherrecovered by, or available for, subsequent wheat crops, suggesting thatcalculations for estimating the N supply from pastures to cereal cropsmustdiscount most N returned in urine by grazing animals.

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18

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.

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Abstract (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.

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19

Wang, Yan-Jing, Ramakrishnan M. Nair, Chun-Sheng Mu e Ian S. Dundas. "Floral morphology and pollination system in the native Australian perennial pasture legume Cullen australasicum (syn. Psoralea australasica)". Crop and Pasture Science 61, n. 12 (2010): 1001. http://dx.doi.org/10.1071/cp10193.

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Abstract (sommario):

Cullen australasicum (syn. Psoralea australasica) is a native perennial legume with potential in the low-rainfall wheatbelt of southern Australia. The objective of this study was to investigate the reproductive biology of C. australasicum utilising five accessions. Glasshouse and field pollination experiments were conducted in Adelaide, South Australia. Floral morphology, stigma receptivity and pollen : ovule ratios were determined. Pollen tube growth and stigma morphology were examined using fluorescence and scanning electron microscopes. Glasshouse pollination studies indicated that four of the accessions showed the need for an external tripping agent to bring about pollination and that hand-tripping was the most efficient method. A scanning electron microscopy study revealed there are two types of stigmas in this species. Stigma receptivity was significantly lower at the early bud stage before anther dehiscence. The results show that C. australasicum is a self-compatible species comprising accessions with a wide range of outcrossing potential.

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20

Bakker, D. M., G. J. Hamilton, D. J. Houlbrooke, C. Spann e A. Van Burgel. "Productivity of crops grown on raised beds on duplex soils prone to waterlogging in Western Australia". Australian Journal of Experimental Agriculture 47, n. 11 (2007): 1368. http://dx.doi.org/10.1071/ea06273.

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Abstract (sommario):

Waterlogging of duplex soils in Western Australia has long been recognised as a major constraint to the production of agricultural crops and pastures. The work described in this paper examines the application of raised beds to arable land that is frequently waterlogged for the production of crops such as wheat, barley, field peas, lupins and canola. Raised beds are 138 cm wide, seed beds separated by 45 cm wide furrows 183 cm apart. These beds were made with a commercial bed former. Seven sites were selected across the south-eastern wheat belt of Western Australia with the experimental areas varying in size from 10 to 57 ha. These large sites were used to accommodate commercial farm machinery. Each site had raised beds formed with a commercial bedformer. The production from the bedded areas was compared with crops grown conventionally on flat ground under minimum tillage as the control. The experiments were established in 1997 and 1998 and the sites were monitored for a maximum of 5 years. In 11 of the 28 site-years of the experiments, grain yields on the raised beds were statistically significantly higher than the yield from crops grown on the control, with an average yield increase of 0.48 t/ha. Across the whole dataset, growing crops on raised beds did not produce significantly lower yields. Below average rainfall was received for much of the experimental period at several sites. Growing season rainfall had a large effect on grain yield and high rainfall over a period of 40 days after seeding significantly increased the grain yield difference between the raised bed and the control. These data indicate that the use of raised beds lead to higher grain yields when seasonal conditions are appropriate.

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21

Behrendt, K., J. M. Scott, D. F. Mackay e R. Murison. "Comparing the climate experienced during the Cicerone farmlet experiment against the climatic record". Animal Production Science 53, n. 8 (2013): 658. http://dx.doi.org/10.1071/an12300.

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Abstract (sommario):

Farming systems research conducted under dryland conditions is subject to the vagaries of the climate during the experimental period. Whether such an experiment experiences a representative series of climatic years must be examined in relation to the longer term climatic record. The Cicerone Project’s farmlet experiment was conducted on the Northern Tablelands of New South Wales, Australia, to investigate the profitability and sustainability of three different management systems: one managed under typical, moderate-input conditions (farmlet B); a second which employed a higher level of pasture inputs and soil fertility (farmlet A); and a third which focussed on the use of moderate inputs and intensive rotational grazing (farmlet C). The climate experienced during the 6.5-year experimental period was compared with the 118-year climatic record, using a biophysical simulation model of grazed systems. The model utilised the long-term daily climate data as inputs and provided outputs that allowed comparison of parameters known to affect grazed pastures. Modelled soil-available water, the number of soil moisture stress days (SMSDs) limiting pasture growth, and growth indices over the experimental period (2000–06) were compared with data over the climatic record from 1890 to 2007. SMSDs were defined as when the modelled available soil moisture to a depth of 300 mm was <17% of water-holding capacity. In addition, minimum temperatures and, in particular, the frequency of frosts, were compared with medium-term (1981–2011) temperature records. Wavelet transforms of rainfall and modelled available soil water data were used to separate profile features of these parameters from the noise components of the data. Over the experimental period, both rainfall and available soil water were more commonly significantly below than above the 95% confidence intervals of both parameters. In addition, there was an increased frequency of severe frosting during the dry winters experienced over the 6.5-year period. These dry and cold conditions were likely to have limited the responses to the pasture and grazing management treatments imposed on the three farmlets. In particular, lower than average levels of available soil water were likely to have constrained pasture production, threatened pasture persistence, and reduced the response of the pasture to available soil nutrients and, as a consequence, livestock production and economic outcomes. Ideally, dryland field experimentation should be conducted over a representative range of climatic conditions, including soil moisture conditions both drier and wetter than average. The drier than average conditions, combined with a higher than normal frequency of severe frosts, mean that the results from the Cicerone Project’s farmlet experiment need to be viewed in the context of the climate experienced over this 6.5-year period.

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22

Syme, H., T. L. Botwright Acuña, D. Abrecht e L. J. Wade. "Nitrogen contributions in a windmill grass (Chloris truncata) - wheat (Triticum aestivum L.) system in south-western Australia". Soil Research 45, n. 8 (2007): 635. http://dx.doi.org/10.1071/sr07159.

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Abstract (sommario):

Chloris truncata, a perennial grass that is native to Australia, has potential as a short-lived summer pasture in rotation with wheat and other winter crops in the low to medium rainfall zone of south-western Australia. In this paper we examine the nitrogen contributions from a C. truncata–wheat system, with the expectation that C. truncata may take up nitrate which would otherwise be lost to leaching, for later release to the following wheat crop. In glasshouse experiments, residual soil nitrate in bare soil was available for uptake and growth of wheat, with a greater response when N was applied. In contrast, wheat grown on C. truncata stubble was mostly reliant on recently mineralised nitrogen, as the previous rotation had depleted the soil of nitrate. Shoot stubble of C. truncata provided sufficient mineralised nitrogen such that the uptake of nitrogen and biomass of wheat equalled those from bare soil. Wheat grown on root stubble of C. truncata had half the biomass production of that grown on either bare soil or shoot stubble, with root + shoot stubble intermediate. In a field trial undertaken at Bruce Rock in Western Australia, nitrogen release from C. truncata stubble at low to intermediate stubble densities increased tiller production, nitrogen uptake, and growth of wheat, but not at the highest N rate in this season, which received below-average rainfall in July. These results provide initial evidence concerning how a C. truncata–wheat system could improve the N balance of the farming system, by potentially reducing the leaching loss of nitrate in autumn, and then releasing mineralised N from stubble when needed by a following wheat crop. While these results require further confirmation, especially in the field, they raise exciting prospects for an improved agronomic system, with potential benefits to N balance, carrying capacity, yield stability, and groundwater discharge. The system requires further study to quantify these processes, and explore their implications.

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23

Bolland, M. D. A., D. G. Allen e K. S. Walton. "Soil testing for phosphorus: comparing the Mehlich 3 and Colwell procedures for soils of south-western Australia". Soil Research 41, n. 6 (2003): 1185. http://dx.doi.org/10.1071/sr02153.

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Abstract (sommario):

Soil samples were collected from 14 long-term field experiments in south-western Australia to which several amounts of superphosphate or phosphate rock had been applied in a previous year. The samples were analysed for phosphorus (P) by the Colwell sodium bicarbonate procedure, presently used in Western Australia, and the Mehlich 3 procedure, being assessed as a new multi-element test for the region. For the Mehlich procedure, the concentration of total and inorganic P in the extract solution was measured. The soil test values were related to yields of crops and pasture measured later on in the year in which the soil samples were collected.The Mehlich 3 procedures (Mehlich 3 total and Mehlich 3 inorganic soil test P values) were similar, with the total values mostly being slightly larger. For soil treated with superphosphate, for each year of each experiment: (i) Mehlich 3 values were closely correlated with Colwell values; and (ii) the relationship between plant yield and soil test P (the soil P test calibration) was similar for the Colwell and Mehlich 3 procedures. However, for soil treated with phosphate rock, the Colwell procedure consistently produced lower soil test P values than the Mehlich 3 procedure, and the calibration relating plant yield to soil test P was different for the Colwell and Mehlich 3 procedures, indicating, for soils treated with phosphate rock, separate calibrations are required for the 2 procedures. We conclude that for soils of south-western Australia treated with superphosphate (most of the soils), the Mehlich 3 procedure can be used instead of the Colwell procedure to measure soil test P, providing support for the Mehlich 3 procedure to be developed as the multi-element soil test for the region.

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24

Lewis, D. C., M. D. A. Bolland, R. J. Gilkes e L. J. Hamilton. "Review of Australian phosphate rock research". Australian Journal of Experimental Agriculture 37, n. 8 (1997): 845. http://dx.doi.org/10.1071/ea96103.

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Abstract (sommario):

Summary. Most of the research on the effectiveness of phosphorus (P) fertilisers in Australia has involved comparing phosphate rock (PR) or partially acidulated PR (PAPR) with superphosphate (SP) or other water-soluble P fertilisers. There are many estimates of effectiveness (current relative effectiveness or CRE) which compared freshly-applied (current) PR and freshly-applied (current) SP. The CRE values for PR range from <0.1 to 2.5, with a mean value for apatite PR of 0.26 and 0.43 for calcined calcium iron aluminium PR (Calciphos). As measured in field experiments in the years after application, and using current SP as a basis for comparison, the residual effectiveness of PR (residual value or RV) is low and constant for up to 11 years after application. Phosphate rock is 5–30% as effective as current SP. The average value of RV for SP declines by about 40% in the first year after application, followed by a further 15% in the second year, and a further 30% over the remaining 6 years. Values of relative effectiveness and RV, and the rate of decline in RV differ substantially between sites and sometimes between plant species. Laboratory studies of reactions between PR and soil have shown that the poor effectiveness of PR is primarily due to the limited extent and rate of dissolution of these fertilisers compared with the almost complete and rapid dissolution of water-soluble P fertilisers. Many Australian soils are only moderately acid (pH in water >5.5) with low pH buffering capacities and they cannot quickly contribute a large supply of hydrogen ions to promote rapid dissolution of PR. Soils are commonly sandy and have low water-holding capacities; in the strongly seasonal Mediterranean climate of south-western and southern Australia, the fertilised surface soil rapidly dries between rains thereby restricting PR dissolution. This restricted dissolution contributes to the poor agronomic effectiveness of PR fertilisers. Studies in Western Australia have shown that the effectiveness of current and residual PR relative to current SP generally decreases with increasing level of application. Therefore, relative to current SP, PR fertilisers become less effective per unit of PR as more is applied to the soil. Consequently, PR fertilisers frequently cannot support the same maximum yield as current SP. Published work indicates that PR fertilisers cannot be regarded as economic substitutes for SP for most agricultural applications in Australia. However, much Australian research has used low reactive PRs in conditions that are not likely to favour even highly reactive PRs. The soils dry out between rains during the growing season and have insufficient hydrogen ions to cause rapid, extensive dissolution of even reactive PR. Research elsewhere has suggested that reactive apatite PRs can be as effective as SP for suitable soils and environments. These are soils that remain wet for the whole growing season and which contain sufficient hydrogen ions to cause rapid dissolution of reactive PR. Laboratory studies, in which there is no P leaching, on 254 different soils collected from throughout south-western Australia showed that 29 soils, all collected from >800 mm average annual rainfall areas, dissolved >40% highly reactive North Carolina PR, suggesting that in the field these soils could be suitable for highly reactive PRs. Insufficient research has been conducted in the high rainfall areas of Australia, where the environment is more likely to favour highly reactive PR, and PAPR made from highly reactive PR. Therefore, a national program was undertaken in 6 Australian states to identify circumstances under which PRs, including reactive PR and PAPR made from reactive PR, may be economic fertilisers for acidic soils in the high rainfall areas of Australia where agricultural production is largely based on pasture production.

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25

Davies, S. L., A. M. Storrie, A. S. Cook, R. A. Latta, A. D. Swan e M. B. Peoples. "Factors influencing herbicide efficacy when removing lucerne prior to cropping". Australian Journal of Experimental Agriculture 46, n. 10 (2006): 1301. http://dx.doi.org/10.1071/ea05220.

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Abstract (sommario):

Farmers often experience inconsistent responses when using herbicides to terminate an established lucerne pasture prior to cropping. In an attempt to redress this problem, a series of field experiments were conducted between 1999 and 2002 at various locations in southern and northern New South Wales, the Australian Capital Territory, and south Western Australia that aimed to identify management guidelines that improved the efficacy of herbicide mixtures commonly used to remove lucerne. Collectively, these studies indicated that herbicides were generally less effective when applied either early (less than 2 weeks) or late (6 weeks or more) in the regrowth cycle of lucerne after defoliation. Herbicide efficacy tended to be greatest if applied to regrowth 3–5 weeks after defoliation, which corresponds to a time when the lucerne crown and root reserves are likely to be in the process of being replenished by photoassimilates transported from the shoot. The impact of timing of herbicide application in relation to season was compared at a number of locations. Across all the sites and years, spring herbicide applications were generally the most effective, removing on average 87% of the lucerne (range 53–100%) compared with 72% in summer (24–100%) and 60% in autumn (7–92%). Spring applications were also more consistent in their effect, removing >80% of the lucerne plants in 9 out of 12 experiments, whereas similar rates of removal occurred on 4 occasions in 9 summer applications and only twice in 8 autumn applications. Some of the seasonal variation could be explained by differences in the amount of rainfall prior to herbicide applications. It was assumed that the relationship between rainfall and herbicide efficacy reflected the stimulation of lucerne shoot and root growth by the additional soil moisture before herbicide treatment. Herbicide mixtures that contained ingredients such as picloram that retain residual activity in the soil tended to be more effective and were less influenced by lucerne growth and season than those herbicides with little or no residual activity. However, such chemicals could potentially restrict which crops can subsequently be grown after a lucerne pasture has been removed. It was concluded that >80% of lucerne plants were likely to be removed using herbicides provided that the herbicide treatment was applied to actively growing lucerne 3–5 weeks after defoliation, and when greater than 70–95 mm rain had fallen in the 6–8 weeks prior to application.

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26

Huxtable, C. H. A., T. B. Koen e D. Waterhouse. "Establishment of native and exotic grasses on mine overburden and topsoil in the Hunter Valley, New South Wales". Rangeland Journal 27, n. 2 (2005): 73. http://dx.doi.org/10.1071/rj05006.

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Abstract (sommario):

Native grasses have an important role to play in mine rehabilitation throughout Australia, but there have been few scientifically designed studies of field establishment of native grasses from sown seed in this country. Current recommendations for rehabilitation of open-cut coal mines in the Hunter Valley involve the sowing of exotic pasture species to reinstate mined land to Class IV and V under the Rural Land Capability System. Despite the importance of native grasses in the pre-mined landscape, they are currently not widely included in mine rehabilitation. To address this issue a project was conducted between 1994 and 2000 to research the use of native grasses for rehabilitation of open-cut coal mines in the Hunter Valley. This paper reports on 2 mine site experiments that aimed to assess establishment and persistence of a broad range of native and exotic grass species from an autumn sowing in both topsoil and raw spoil over a period of 61 months. The most promising natives in terms of early establishment, persistence and spread over time, included six C3 accessions (five Austrodanthonia spp. and Austrostipa bigeniculata) and one C4 accession (Cynodon dactylon). Persistence of these accessions was better in raw spoil than topsoil, despite initial low numbers, due to a lack of weed competition and their ability to spread by self-seeding. In topsoil, and in the absence of any biomass reduction, native species were mostly out-competed by vigorous exotic perennial grasses which were sown in these experiments and from seed influx from adjacent rehabilitation areas or from the soil seed bank. The effects of climatic conditions and differences in soil physical, chemical and seed bank characteristics at the 2 mine sites are also discussed.

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27

Braunberger, P. G., L. K. Abbott e A. D. Robson. "Early vesicular-arbuscular mycorrhizal colonisation in soil collected from an annual clover-based pasture in a Mediterranean environment: soil temperature and the timing of autumn rains". Australian Journal of Agricultural Research 48, n. 1 (1997): 103. http://dx.doi.org/10.1071/a96049.

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Abstract (sommario):

The results of 2 experiments investigating the early stages of the formation of vesicular- arbuscular (VA) mycorrhizas in response to both soil temperature and the timing of autumn rains are reported for a Mediterranean environment in the south-west of Western Australia. In Expt 1, treatments including an early break, a late break, and a false break followed by a late break were applied to a mixed and sieved field soil collected dry in the summer and placed in pots in a glasshouse. In each break, pots were watered to field capacity and planted with subterranean clover (Trifolium subterraneum) or capeweed (Arctotheca calendula). In early and false breaks, both initiated on the same day in early autumn, the soil temperature was maintained at 30°C, and in the late break, initiated 50 days later in autumn, the soil temperature was maintained at 18°C. In both early and late breaks, pots were watered to field capacity for either 21 or 42 days when plant and mycorrhizal variables were assessed. In a false break, pots were watered to field capacity for 7 days after which the soil was allowed to dry and newly emerged plants died. These pots were then rewatered and replanted at the same time as pots receiving a late break, and subjected to the same soil temperature (18°C). In Expt 2 performed the following year, soil temperature was maintained at 31 or 18°C in both early and late breaks. Pots were planted with clover and watered to field capacity for 21 or 42 days, when plant and mycorrhizal variables were assessed. In Expt 1, VA mycorrhizal colonisation of both clover and capeweed was initially low in an early break compared with levels observed in a late break. Only mycorrhizas formed by Glomus spp. were observed in the early break, whereas mycorrhizas of Glomus, Acaulospora, and Scutellospora spp. and fine endophytes were observed in the late break. Colonisation was decreased by a false break, predominantly because of a decrease in formation of mycorrhizas of Glomus spp. In Expt 2, mycorrhizas of Glomus spp. predominated in warm soil in both early and late breaks and mycorrhizas of Acaulospora spp., Scutellospora spp., and fine endophytes were observed in greater abundance in cool soil in early and late breaks. These experiments indicate that soil temperature at the time of the break will have a large impact on both the overall levels of VA mycorrhizal colonisation of pasture plants and colonisation by different fungi. In addition, fungi that remain quiescent in warm soil may avoid damage in a false break.

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28

Brennan, R. F., e M. D. A. Bolland. "Residual values of soil-applied zinc fertiliser for early vegetative growth of six crop species". Australian Journal of Experimental Agriculture 46, n. 10 (2006): 1341. http://dx.doi.org/10.1071/ea05154.

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Abstract (sommario):

Zinc (Zn) oxide is the most widely used fertiliser for the predominantly acidic to neutral soils of south-western Australia. For these soils, the residual value of Zn oxide has been determined for wheat and lupin, but not for barley, oats, canola and triticale, which are also grown in the region. Just after termination of a long-term (17 year) field experiment that measured the residual value of Zn oxide for wheat, soil samples were collected from selected plots to use in 2 glasshouse experiments. The field experiment was on previously unfertilised, newly cleared duplex soil (sand with much lateritic ironstone gravel over clay) and before the experiment started DTPA extractable Zn for the top 10 cm of soil was <0.2 mg Zn/kg. In the first glasshouse experiment, soil samples from the nil-Zn treatment of the field experiment were used to measure the critical Zn concentration in young mature growth of 6 crop species (wheat, barley, oats, lupin, canola and triticale) when 7 levels of Zn (0, 50, 100, 150, 200, 300 and 600 mg Zn/kg soil) were applied to the soil. In the field experiment, 0.5 and 1.0 kg Zn/ha, as Zn oxide, had been applied once only in each of the following years to previously nil-Zn plots: 1983, 1984, 1986, 1990, 1992, 1996 and 2000. Soil samples were collected from these plots to use in the second glasshouse experiment. This experiment estimated how long the Zn treatments applied in the field remained effective, as estimated using shoot yields and critical Zn concentrations in young mature growth of the same 6 crop species used in experiment 1. Critical Zn concentration in young mature growth was about 14 mg/kg for wheat, barley and lupin, 15 mg/kg for triticale, and 18 mg/kg for oats and canola. The residual value of Zn varied with crop species. As estimated from shoot yields, the 0.5 kg Zn/ha treatment was effective for ≤10 years for wheat, barley and oats, ≤14 years for lupin and canola, and >17 years for triticale. The 1.0 kg Zn/ha treatment remained fully effective for all crop species. As determined from projected estimates of the data, the time taken for Zn concentrations in young mature growth to reach critical values, the residual value of the 0.5 and 1.0 kg Zn/ha treatments were least for wheat, barley and oats, were greater for lupin and canola, and greatest for triticale. There were a total of 7 wheat crops and 10 pasture years during the 17 years of the field experiment. For the 0.5 and 1.0 kg Zn/ha treatment applied in the field in 1983, 30–34% of the applied Zn was removed in grain of the 7 wheat crops grown before soil samples were collected to do the glasshouse experiments. The pasture was grazed by sheep and it was estimated that 16–24% of the Zn applied in 1983 may have been removed in wool and meat. Removal of Zn in grain and animal products therefore decreased the residual value of the Zn oxide fertiliser.

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29

Batson, M. G. "Agrostis castellana (Poaceae), Dominant Agrostis Species, Found in Bent Grass Pastures in South-eastern Australia". Australian Journal of Botany 46, n. 6 (1998): 697. http://dx.doi.org/10.1071/bt97065.

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There is considerable uncertainty that the traditional identification of bent grasses in south-eastern Australia as Agrostis capillaris L. (Syn. Agrostis tenuis Sibth.) is correct, due to a history of confusing nomenclature and mis-identification. Bent grass is considered a weed of pastures in the high-rainfall zone of south-eastern Australia and thus the correct identity of bent grass may have implications for its management and control. Populations of bent grass were sampled from 42 pastures in south-eastern Australia and Agrostis castellana Boiss. et Reuter, rather than A. capillaris, was found to be the dominant species of Agrostis in 33 out of 42 bent grass pastures sampled. Five of the nine pastures sampled in Tasmania contained A. capillaris as opposed to only 1 of the 33 pastures sampled in Victoria. Agrostis castellana had not been identified in Victoria or Tasmania prior to this work. Since A. castellana grows more vigorously by rhizomes than A. capillaris, control measures recommended for A. capillaris may not be relevant for bent grass pastures in south-eastern Australia. Ligule length, ligule width and width of lamina, measured to determine whether species of bent grass could be easily distinguished in the field, did not distinguish adequately between A. castellana and A. capillaris.

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30

Mitchell, M. L., M. R. McCaskill e R. D. Armstrong. "Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia". Crop and Pasture Science 70, n. 12 (2019): 1044. http://dx.doi.org/10.1071/cp19217.

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Abstract (sommario):

Approximately 3.1 Mha (22%) of the agricultural area of south-eastern Australia can be classified as native pasture. There is the assumption that, owing to the widespread occurrence of low-fertility soils in Australia, native grass species do not respond to increased phosphorus (P) fertility. Currently, there are no industry recommendations of target soil-test P values for native-grass-based pastures. This paper reviews the responses of perennial native pasture species endemic to south-eastern Australia to P application in controlled environments, surveys, replicated experiments and paired-paddock trials. Eighty-seven site-years of trial data where different levels of P were applied, conducted over the last two decades, on native-based pastures in south-eastern Australia are reviewed. Data indicate that application of P fertilisers to native grass pastures can increase dry matter (DM) production and maintain pasture stability. However, minimum targets for herbage mass (800 kg DM/ha) and groundcover (80%) are required to ensure persistence of perennial native grasses. Stocking rates also need to match carrying capacity of the pasture. Based on previous research, we recommend target soil-test (Olsen; 0–10 cm) P levels for fertility-tolerant native grass pastures, based on Microlaena stipoides, Rytidosperma caespitosum, R. fulvum, R. richardsonii, R. duttonianum and R. racemosum, of 10–13 mg/kg, whereas for pastures based on fertility-intolerant species such as Themeda triandra, lower levels of <6 mg/kg are required to ensure botanical stability.

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31

Grainger, C., T. Clarke e R. J. Eckard. "Effect of whole cottonseed supplementation on energy and nitrogen partitioning and rumen function in dairy cattle on a forage and cereal grain diet". Australian Journal of Experimental Agriculture 48, n. 7 (2008): 860. http://dx.doi.org/10.1071/ea07400.

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Abstract (sommario):

The experimental objective was to determine the effect of adding whole cottonseed (WCS) to a forage and cereal grain diet on the energy and nitrogen balance and rumen function of lactating dairy cattle. Two experiments were carried out, a field experiment and an indoor metabolism experiment. In the field experiment, 50 lactating cows ~200 days in milk were randomly allocated to one of two groups (control or WCS). Cows were offered lucerne hay (morning) and ryegrass-based pasture silage (afternoon) in one group for 5 weeks. The hay and silage were placed on the ground in a bare paddock. Cows in each group were also individually offered cracked grain in a feed trough at 3 kg dry matter (DM)/cow.day at milking times. In addition, at milking times, cows in the WCS group were individually offered 2.7 kg DM/cow.day of WCS with their grain supplement. Samples of rumen fluid were collected from each fistula, ~4 h after grain feeding in the morning, of eight cows (four per group) on 1 day in each of the 5 weeks of treatment. In the metabolism experiment, immediately after the 5 weeks of feeding, 12 lactating cows, six from each treatment from the field experiment, were randomly selected and individually housed in metabolism stalls and fed the same diets for a 6-day energy and nitrogen balance study. Cows were fed at milking times (0700 and 1530 hours) and all feed offered and refused was weighed daily. All cows were offered 5.6 kg DM/cow.day of pasture silage, 4 kg DM/cow.day of lucerne hay and 3 kg DM/cow.day of cereal grain. In addition, cows in the WCS treatment group were offered 2.7 kg DM/cow.day of WCS with their grain supplement. In the metabolism study, adding WCS to the diet resulted in a greater energy intake, but there was no depression in energy digestibility. Whole cottonseed also increased nitrogen intake and nitrogen digestibility of the diet was increased from 62 to 75%, but the proportion of nitrogen in milk remained the same with a greater proportion of nitrogen appearing in body tissue. In the field experiment, supplementation with WCS did not alter rumen fluid ammonia-N or volatile fatty acid concentrations. Adding WCS did not affect three of the main classes of protozoa, based on size, within the two major orders of ciliate protozoa. The WCS did, however, reduce the levels of entodiniomorphs >200 µm diameter and holotrichs < 200 µm diameter, but these only account for a small number of the total protozoa present. Supplementation of a forage and grain-based diet with WCS improved the energy and protein content of the diet without any negative effects on rumen digestion and with a similar proportion of dietary energy and nitrogen appearing in milk. Over the summer period in winter-rainfall dairying areas in south-east Australia when pasture availability is limited and the diet is mainly comprised of forage and cereal grain fed at a level that is energy-limiting for maximum production, WCS can be and is used to supplement the diet to improve milk yield and profitability.

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32

McCormick, Jeff I., Richard C. Hayes, Guangdi D. Li e Mark R. Norton. "A review of pasture establishment by undersowing with special reference to the mixed farming zone of south-eastern Australia". Crop and Pasture Science 65, n. 10 (2014): 956. http://dx.doi.org/10.1071/cp14049.

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Abstract (sommario):

Pastures continue to provide essential functions for the mixed-farming zone in south-eastern Australia, where crop and livestock production are integral parts of most farms. Establishment of pastures in this zone needs to be low-cost and preferably with minimal risk. Pastures are typically sown either directly or in combination with a cover-crop (also called undersowing; the practice of sowing pasture seed simultaneously with a crop that is intended for grain production in the first year), so that the establishment cost is offset by income from the sale of grain. The purposes of this review are to: (i) draw together the literature on undersowing pastures, including studies conducted since the previous review in 1965; (ii) understand why there is a discrepancy between research results that generally do not support the practice of undersowing pastures, whereas farmer preference appears to establish pastures under a cover-crop; and (iii) identify critical needs for further research to aid in making decisions about pasture establishment on-farm. Published and unpublished data from the Australian wheatbelt on establishing pastures by undersowing was examined from the 1920s to the present and included seven publications for perennial species from 26 different experiments. Eight publications addressing establishment of annual species were available from 30 experiments. Many trials appear to have been conducted without being analysed or published. A further 16 international publications were reviewed. Generally, cover-crops reduced annual pasture seedset and perennial density even though the pastures established under the cover-cropping were commonly deemed ‘satisfactory’ by the authors. Pasture establishment was improved by reducing the sowing rate of the cover-crop and/or sowing on alternate rows. Technological change during the past 25 years has led to different configurations of seeding machinery, increased use of herbicides and longer cropping phases. Conclusions previously reached may therefore need to be re-assessed. No data published quantified the risks associated with undersowing on a seasonal and regional basis to determine the probability of success, and there are insufficient data to model the complex physiological interactions between crop and pasture, with most experiments focused on basic agronomic parameters. Furthermore, long-term effects of establishment method on total pasture biomass production and subsequent effects on following crops have rarely been demonstrated, because of the short time-frames in which most experiments have been conducted. Farmers in the mixed-farming zone still prefer to establish pastures under a cover-crop because of perceived financial benefit of the practice. This review identifies substantial research gaps to be addressed to improve pasture-establishment decisions.

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33

Kemp, D. R., e P. M. Dowling. "Towards sustainable temperate perennial pastures". Australian Journal of Experimental Agriculture 40, n. 2 (2000): 125. http://dx.doi.org/10.1071/ea98003.

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Abstract (sommario):

Naturalised pastures across the higher rainfall (>600 mm) perennial pasture zone of south-eastern Australia are less productive than they were, while sown pastures fail to maintain their initial levels of production. Several factors have contributed to this, including lack of knowledge of suitable grazing practices, weed invasion, increasing acid soils, rising water tables and poor management practices during droughts. A key issue in each case is the decline in perennial grass species which is both a cause and effect of the decline in productivity and sustainability of these ecosystems. This paper introduces a volume devoted to the largest collaborative study done to evaluate tactics for better grazing management and to improve the sustainability of perennial pasture ecosystems. Grazing practices to manage the composition of pastures have been largely neglected in pasture research, but are an important first step in improving pasture sustainability. This paper also outlines a new, open communal grazing experimental design which was developed and used across 24 sites on farms in New South Wales, Victoria, Tasmania and South Australia, to evaluate tactics for grazing management. The general aim across these experiments was to maintain (if adequate) or enhance (if degraded), the proportion of desirable perennial grasses in the sward to achieve more sustainable pastures. The results will provide the basis for building more sustainable grazing systems.

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34

Mitchell, GJ, RJ Carter e SR Chinner. "Studies on the control of water-dropwort (Oenanthe pimpinelloides) in South Australia". Australian Journal of Experimental Agriculture 35, n. 4 (1995): 483. http://dx.doi.org/10.1071/ea9950483.

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Abstract (sommario):

Water-dropwort (Oenanthe pimpinelloides L.), a tuberous perennial herb, is currently known in South Australia from only a single locality in the Mount Lofty Ranges. There is little information on water-dropwort control, and 2 experiments were conducted to assess the effects of sowing pasture, with or without presowing herbicides, on the control of this weed. Phalaris (Phalaris aquatica L.) and perennial clovers were successfully introduced into infested pastures by direct drilling in autumn. Water-dropwort regenerated from seed more densely in unsown plots than plots of established perennial pasture, suggesting that upgrading pastures may be a strategy to reduce the rate of spread by seed of this weed. A range of herbicide treatments applied to waterdropwort at the stem elongation stage in spring before autumn sowing of pastures provided effective shortterm control. The best short-term control was provided by glyphosate at 1440 g a.i./ha; metsulfuron methyl at 6, 12, and 36 g a.i./ha; and metsulfuron methyl at 12 g a.i./ha tank-mixed with glyphosate or 2,4-D amine at 720 or 1000 g a.i./ha, respectively. These treatments, and chlorsulfuron at 21 g a.i./ha, also significantly (P<0.05) reduced water-dropwort abundance (relative to untreated areas) for up to 18 months after sowing and initially improved the density of sown pasture species, but these improvements were not evident 14 months after resowing. Although prior season herbicide treatments controlled water-dropwort in newly sown pastures, 2 separate applications of herbicides, in May and October, gave no better control of water-dropwort than a single herbicide application in spring. Water-dropwort infestations do not appear to prevent successful direct drilling of phalaris and perennial clovers. Although pasture renovation did not provide long-term suppression of water-dropwort, the maintenance of vigorous pastures may reduce the rate of population growth from seedlings of this weed. Recropping restrictions may limit the role of chlorsulfuron for water-dropwort control in pasture renovation situations.

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35

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.

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Abstract (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.

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36

Chan, K. Y., A. Oates, G. D. Li, M. K. Conyers, R. J. Prangnell, G. Poile, D. L. Liu e I. M. Barchia. "Soil carbon stocks under different pastures and pasture management in the higher rainfall areas of south-eastern Australia". Soil Research 48, n. 1 (2010): 7. http://dx.doi.org/10.1071/sr09092.

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Abstract (sommario):

In Australia, pastures form the basis of the extensive livestock industries and are important components of crop rotation systems. Despite recent interest in the soil carbon sequestration value of pastures in the mitigation of climate change, little information is available on the soil carbon sequestration potential of pastures in New South Wales farming systems. To quantify the soil carbon stocks under different pastures and a range of pasture management practices, a field survey of soil carbon stocks was undertaken in 2007 in central and southern NSW as well as north-eastern Victoria, using a paired-site approach. Five comparisons were included: native v. introduced perennial, perennial v. annual, continuous v. rotational grazing, pasture cropping v. control, and improved v. unimproved pastures. Results indicated a wide range of soil organic carbon (SOC) stocks over 0–0.30 m (22.4–66.3 t C/ha), with little difference when calculated based on either constant soil depth or constant soil mass. Significantly higher SOC stocks were found only as a result of pasture improvement using P application compared with unimproved pastures. In this case, rates of sequestration were estimated to range between 0.26 and 0.72 t C/ha.year, with a mean rate of 0.41 t C/ha.year. Lack of significant differences in SOC stocks for the other pastures and pasture management practice comparisons could be due to inherent problems associated with the paired-site survey approach, i.e. large variability, difficulties in obtaining accurate site history, and the occasional absence of a valid control as well as the likely lower rates of SOC sequestration for these other comparisons. There is a need for scientific long-term trials to quantify the SOC sequestration potential of these other pastures and pasture management practices.

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37

Sandral, Graeme A., Andrew Price, Shane M. Hildebrand, Christopher G. Fuller, Rebecca E. Haling, Adam Stefanski, Zongjian Yang et al. "Field benchmarking of the critical external phosphorus requirements of pasture legumes for southern Australia". Crop and Pasture Science 70, n. 12 (2019): 1080. http://dx.doi.org/10.1071/cp19014.

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Abstract (sommario):

In recent decades several pasture legumes have been available in southern Australia as potential alternatives to the most widely used annual pasture legume Trifolium subterraneum. Little is known about their soil phosphorus (P) requirements, but controlled environment experiments indicate that at least some may differ in their P fertiliser requirements. In this study, pasture legume varieties, including T. subterraneum as the reference species, were grown at up to four sites in any one year over a 3-year period (in total, seven site × year experiments) to measure herbage growth responses in spring to increased soil P availability. A critical soil test P concentration (corresponding to 95% maximum yield) was estimated for 15 legumes and two pasture grasses. The critical soil P requirements of most of the legumes did not differ consistently from that of T. subterraneum, indicating their soil fertility management should follow the current soil test P guidelines for temperate Australian pastures. However, the critical P requirement of Medicago sativa was higher than that of T. subterraneum, but remains ill-defined because extractable soil P concentrations in these experiments were often not high enough to permit a critical P estimate. Three forage crop legumes (Trifolium incarnatum, Trifolium purpureum, Trifolium vesiculosum) and two pasture legumes (Ornithopus compressus, Ornithopus sativus) had lower critical soil test P concentrations. It may be feasible to manage pastures based on these species to a lower soil test P benchmark without compromising yield.

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38

Hill, J. O., M. J. Robertson, B. C. Pengelly, A. M. Whitbread e C. A. Hall. "Simulation modelling of lablab (Lablab purpureus) pastures in northern Australia". Australian Journal of Agricultural Research 57, n. 4 (2006): 389. http://dx.doi.org/10.1071/ar05263.

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Abstract (sommario):

The capability to simulate lablab production across a range of environments in northern Australia provides a useful tool for exploring agronomic and management options and risk assessments for the crop. This paper reports on the development and testing of a model of lablab (annual cultivar cv. Highworth and perennial cultivar cv. Endurance) growth, designed for use in the cropping systems simulator, APSIM (Agricultural Production Systems Simulator). Parameters describing leaf area expansion, biomass accumulation, and partitioning were derived from field experiments, and other essential parameters were assumed from similar tropically adapted legumes. The model was tested against data from experiments including different locations, cultivars, sowing dates, soil types, and water availability. Observed biomass ranged from 63 to 13055 kg dry matter/ha and was predicted by the model in an independent test with a root mean square deviation of 770 kg dry matter/ha. Observed time courses of biomass production for both the annual and perennial cultivars were reproduced well, as was the partitioning of biomass into leaves and stems. The effect of variable rainfall and temperature in northern Australia was analysed using the model and historical climate data. Yield reductions were found in the more inland and southern-most parts of the region where summer rainfall and/or temperatures are lower.

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39

Garden, D. L., G. M. Lodge, D. A. Friend, P. M. Dowling e B. A. Orchard. "Effects of grazing management on botanical composition of native grass-based pastures in temperate south-east Australia". Australian Journal of Experimental Agriculture 40, n. 2 (2000): 225. http://dx.doi.org/10.1071/ea98010.

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Abstract (sommario):

Grazing management strategies to alter botanical composition of native pastures were investigated at 4 locations in the high rainfall zone of south-east Australia, including Tasmania. These studies were conducted as part of the Temperate Pasture Sustainability Key Program, which evaluated the effects of grazing management on a wide range of pasture types between 1993 and 1996. Pastures in this study were based on Aristida ramosa/Bothriochloa macra, Microlaena stipoides–Austrodanthonia spp. or Themeda triandra–Austrodanthonia spp. Seasonal rests, increased grazing pressure in spring, mob stocking and cutting for hay were compared to continuous grazing at all sites. In addition, specific local treatments were tested at individual sites. Changes in composition resulting from the treatments were minimal at most sites. This may have been due to a combination of the inherent stability of the pastures, the relatively short duration of the experiments, and the drought conditions experienced, which minimised differences between treatments. Some strategies to alter composition of natural pastures are suggested. In the Aristida–Bothriochloa pasture there was a general decrease in Aristida and an increase in Bothriochloa, which was largely unaffected by the type of grazing management applied. The combination of drought conditions and increasing grazing pressure was sufficient to alter composition without specific management strategies being necessary. In the Themeda–Austrodanthonia pasture, resting in spring, 12-month rests or cutting for hay (which involved a spring rest) allowed Themeda to increase in the pasture. The Microlaena–Austrodanthonia pastures were very stable, especially where annual grass content was low. However, certain treatments allowed Microlaena to increase, a result which is regarded as being favourable. The major effects in these latter pastures were on undesirable species. Vulpia spp. were reduced by resting in autumn and increased spring grazing pressure, while Holcus lanatus was increased dramatically by resting in spring and was also increased by resting in autumn or winter, but only when conditions were suitable for growth of this species. In many cases, treatment differences were only expressed following recovery from drought, showing that timing of grazing management to achieve change is critical.

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40

Orgill, Susan E., Jason R. Condon, Mark K. Conyers, Stephen G. Morris, Brian W. Murphy e Richard S. B. Greene. "Parent material and climate affect soil organic carbon fractions under pastures in south-eastern Australia". Soil Research 55, n. 8 (2017): 799. http://dx.doi.org/10.1071/sr16305.

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Abstract (sommario):

In the present field survey, 72 sites were sampled to assess the effect of climate (Monaro, Boorowa and Coleambally regions) and parent material (Monaro region only; basalt and granite) on soil organic carbon (OC) under perennial pastures. In the higher-rainfall zone (Monaro and Boorowa; >500mm mean annual rainfall), OC stocks under introduced and native perennial pastures were compared, whereas in the lower-rainfall zone (Coleambally; <500mm mean annual rainfall) OC stocks under crops and pastures were compared. Carbon fractions included total OC (TOC), particulate OC (POC), resistant OC (ROC) and humic OC (HUM). Higher OC stocks were associated with higher spring and summer rainfall and lower annual temperatures. Within a climatic zone, parent material affected the stock of OC fractions in the 0–30cm soil layer. Within a climatic zone, when grouped by parent material, there was no difference in OC stock with vegetation type. There were significant correlations between soil factors associated with parent material and OC concentration, including negative correlations between SiO2 and HUM (P<0.05) and positive correlations between cation exchange capacity and TOC, POC and ROC (P<0.01). TOC was also positively correlated with total nitrogen (N) and available sulfur (S; P<0.05), indicating organic matter in soil is important for N and S supply for plant production in the studied regions, and vice versa. Although ensuring adequate available S may increase OC stocks in south-eastern Australia, the large stock of OC in the soil under perennial pastures, and the dominating effect of climate and parent material on this stock, may mean that modest increases in soil OC due to management factors go undetected.

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41

Maino, James L., Matthew Binns e Paul Umina. "No longer a west-side story – pesticide resistance discovered in the eastern range of a major Australian crop pest, Halotydeus destructor (Acari: Penthaleidae)". Crop and Pasture Science 69, n. 2 (2018): 216. http://dx.doi.org/10.1071/cp17327.

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Abstract (sommario):

The redlegged earth mite, Halotydeus destructor (Tucker) (Acari: Penthaleidae), is an important pest of pastures, broad-acre crops, and vegetables across southern Australia. Populations of H. destructor in Western Australia have been known to be resistant to pyrethroid and organophosphorus pesticides since 2006 and 2014, respectively. Resistant populations are currently widespread across Western Australia’s southern growing region but have, until now, remained undetected in the large south-eastern Australian range of H. destructor, despite ongoing resistance screening since 2006. Following reports of a field control failure in the Upper South East district in South Australia in 2016, resistance testing determined this South Australian population was resistant to pyrethroid and organophosphorus pesticides. The levels of resistance discovered were similar to resistant H. destructor populations in Western Australia, which are associated with chemical control failures. This work confirms for the first-time that pesticide resistant populations of H. destructor are no longer isolated to Western Australia.

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42

Cox, JW, DJ Mcfarlane e RW Skaggs. "Field-evaluation of DRAINMOD for predicting waterlogging intensity and drain performance in South-Western Australia". Soil Research 32, n. 4 (1994): 653. http://dx.doi.org/10.1071/sr9940653.

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Abstract (sommario):

Waterlogging is common on sloping duplex soils in south-western Australia and causes damage to non-irrigated cereal crops and pastures. The factors which affect the performance of surface seepage interceptor drains installed to reduce this waterlogging are complex because the soils are very variable and have preferred pathways for groundwater flow. We compared DRAINMOD's predictions with field measured waterlogging intensity and drain flow over 3 years near Mt Barker and Narrogin in Western Australia. DRAINMOD failed to accurately predict waterlogging intensities and drain flows because water can move through macropores which bypass the soil matrix. At Mt Barker, DRAINMOD overpredicted waterlogging intensity by between 120% in a wet year and 650% in a very dry year. Drain flows were underpredicted by 148% in the driest year. At Narrogin, DRAINMOD underpredicted waterlogging intensity each year (rainfall was below average each year) and drain flow in the driest two years. However, by increasing Ks of the topsoil and adjusting Ks of the subsoil clay, DRAINMOD predictions agreed with measured responses. DRAINMOD can be used to predict waterlogging intensities and drain flows in duplex soils in the >450 mm annual rainfall areas of south-western Australia provided adjustments are made to the field point-measured Ks. Reliability increases with increasing rainfall during the growing season.

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43

Kemp, D. R., D. L. Michalk e J. M. Virgona. "Towards more sustainable pastures: lessons learnt". Australian Journal of Experimental Agriculture 40, n. 2 (2000): 343. http://dx.doi.org/10.1071/ea99001.

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Abstract (sommario):

The Temperate Pasture Sustainability Key Program (TPSKP) was established across south-eastern Australia to test the hypotheses that an improved perennial grass content in pastures would result in fewer weeds, better water use (and hence lesser impacts on soil salinity), and lower soil acidification rates. Grazing tactics were seen as a means to enhance or maintain the perennial grass content. Soil and water sustainability experiments in summer and winter dominant rainfall environments showed fewer weeds, improvements in water use and less acidity under perennial versus annual grass pastures. Further work is needed to determine if these gains are sufficient to make perennial grass pastures sustainable in the long-term as some nitrate leakage still occurred at the winter rainfall site. Indicators were developed to rate the sustainability of treatments within experiments. A subset of these indicators was common across experiments and could readily be used by farmers to provide an initial assessment of the soil and water sustainability of their pasture systems. These are: the mineral nitrogen at the bottom of the root zone (40–60 cm); soil pH at the surface and bottom of the root zone and perennial grass content by species. Managing pastures through droughts is a critical aspect of grazing management in Australia. Experiments within the TPSKP demonstrated that perennial grasses survived during drought when maintained above critical lower biomass values. These values ranged from 0.5 to 1.5 t DM/ha depending upon species. Over all experiments, there was general support for the view that maintaining a higher level of biomass in pastures resulted in more sustainable systems. Twenty-three grazing experiments using an open communal grazing design showed that most perennial grasses were sensitive to grazing at some stage in their seasonal growth cycles. The exceptions were inconclusive for several reasons e.g. the grazing pressure may not have been high enough at those sites to elucidate any effects; they occurred where the perennial grass content was less than 10% or exceeded 70%, of the sward; or were confounded by interactions between species where the species under study was not dominant. After taking these exceptions into account, it was then possible to determine where grazing tactics could be expected to work. Species differed in their response to grazing. Some perennial grasses were more sensitive to grazing during periods of stress (e.g. dry summers) than when actively growing (e.g. cocksfoot), while the reverse applied with others (e.g. phalaris). Of the grasses sensitive to grazing when actively growing, sensitivity of some was largely confined to the reproductive period (e.g. perennial ryegrass). Across most experiments, continuous grazing resulted in either a decline in or no net benefit to, the perennial grass content. Microlaena stipoides was the only species to respond to increased grazing pressure — this only applied in spring. The experiments clearly showed that tactical rests were an important tool for grassland management. The effects recorded were predominantly expressed through impacts on vegetative growth and survival of existing plants. Short-term experiments and dry seasons did not enable recruitment processes to be studied. Within pastures, grazing tactics can influence many species. The challenge is to use the TPSKP outcomes to develop strategies that optimise the composition of these swards. Due to the short-term nature of these experiments the results were evaluated within a conservative framework and often simply on the absolute level of parameters. Techniques need to be developed to more effectively monitor the process (i.e. rates of change), rather than the consequences (i.e. ends). The information gained in this program needs to be incorporated into practical strategies for better management of pastures and tested at a commercial scale. The TPSKP was one of the largest, coordinated pasture programs ever attempted. Some major outcomes were the experience gained by a large number of grassland scientists in running such programs, the development and acceptance of standardised measurement protocols and a much stronger network among grazing systems scientists committed to achieving improved management systems.

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44

White, R. E., K. R. Helyar, A. M. Ridley, D. Chen, L. K. Heng, J. Evans, R. Fisher et al. "Soil factors affecting the sustainability and productivity of perennial and annual pastures in the high rainfall zone of south-eastern Australia". Australian Journal of Experimental Agriculture 40, n. 2 (2000): 267. http://dx.doi.org/10.1071/ea98013.

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A field study was carried out in the high rainfall zone (HRZ, >600 mm p.a.) of southern Australia from March 1994 to August 1997 to test the hypothesis that sown perennial grasses and liming could make the existing pastures more sustainable through better use of water and nitrogen. The site, on an acid duplex soil at Book Book near Wagga Wagga in southern New South Wales, was typical of much of the HRZ grazing country in southern New South Wales and north-east Victoria. The experiment consisted of 4 replicate paddocks (each 0.135 ha) of 4 treatments: annual pasture (mainly ryegrass Lolium rigidum, silver grass Vulpia spp., subterranean clover Trifolium subterraneum and broadleaf weeds) without lime, annual pasture with lime, perennial pasture (phalaris Phalaris aquatica, cocksfoot Dactylis glomerata and subterranean clover T. subterraneum) without lime, and perennial pasture with lime. Soil pH (0–10 cm) in the limed treatments was maintained at 5.5 (0.01 mol/L CaCl2), compared to 4.1 in the unlimed treatments. The pastures were rotationally grazed with Merino ewe or wether hoggets at a stocking rate which varied with the season, but was 10–25% higher on the limed pastures [14.8–17.3 dry sheep equivalent (dse)/ha] than the unlimed pastures. One replicate set of pasture treatments was intensively monitored for surface runoff, subsurface flow (at the top of the B horizon), water potential gradients and ammonium volatilisation. Other measurements of nitrogen inputs, transformations and losses were made on all paddocks. In a normal to wet year, surface runoff, subsurface flow and deep drainage (>180 cm depth) were about 40 mm less from the perennial than the annual pastures. The reduction in deep drainage under the perennials was about one-third to one-half (20–29 mm/year). The smaller loss of solution NO3– from the perennial pastures (up to 12 kg N/ha.year) suggested soil acidification under perennials was reduced by about 1 kmol H+/ha.year. Denitrification and volatilisation losses of N were small (1–12 kg N/ha.year). Nitrogen fixed by subterranean clover (above ground parts) ranged from 2–8 kg N/ha in the drought of 1994–95 to 128 kg N/ha in a normal year (1996). The soil-pasture nitrogen balance was positive for all treatments and averaged 76 kg N/ha.year over 2 years. The abundance of introduced and native earthworms increased from 85 to 250/m2 in the limed pastures between 1994 and 1997. Introduced species, such as Aporrectodea trapezoides, were especially responsive to lime. Animal production per hectare was 10–25% higher on pastures with lime. Critical gross margins per dse were lowest ($16/ha) for a long-lived perennial pasture (>15 years), and highest ($20/ha) for a short-lived perennial (5 years). Overall, there were substantial benefits in animal production, improved soil quality and water use from establishing perennial grass pastures with lime on these strongly acid soils.

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45

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.

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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.

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46

Jones, Roger A. C. "Virus diseases of pasture grasses in Australia: incidences, losses, epidemiology, and management". Crop and Pasture Science 64, n. 3 (2013): 216. http://dx.doi.org/10.1071/cp13134.

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This paper reviews current knowledge for Australia over the occurrence, losses caused, epidemiology, and management of virus diseases of pasture grasses. It also reviews all records of viruses in wild grasses likely to act as alternative host reservoirs for virus spread to nearby pastures or crops. Currently, 21 viruses have been found infecting 36 pasture or forage grass species and 59 wild grass species. These viruses are transmitted by arthropod vectors (mites or insects) or, in one instance, via grass seeds. Their modes of transmission are critical factors determining their incidences within pastures in different climatic zones. Large-scale surveys of perennial grass pastures growing in regions with temperate–Mediterranean climates revealed that Barley yellow dwarf virus (BYDV), Cereal yellow dwarf virus (CYDV), and Ryegrass mosaic virus (RyMV) sometimes reach high infection incidences. The same was true for BYDV and CYDV when perennial pasture grasses and wild grasses growing outside pastures were surveyed to establish their occurrence. Smaller scale surveys of grasses growing both inside and outside annual pastures found that Wheat streak mosaic virus (WSMV) infection could also reach high incidences in some annual grass species. Herbage yield loss data are available demonstrating potentially serious impacts on pasture production under Australian conditions from BYDV infection in perennial ryegrass swards, and from RyMV infection in both perennial and Italian ryegrass swards. Also, infection with BYDV or RyMV diminished the ability of infected pasture grass plants to compete with pasture legumes or weeds. Host resistance to BYDV, CYDV, and/or RyMV has been identified within a few temperate–Mediterranean pasture grasses, and is available for use in Australian pasture breeding programs. Integrated Disease Management tactics involving phytosanitary, cultural, chemical, and host resistance measures were devised against BYDV, CYDV, and RyMV infection in mixed species pasture, but no field experiments were undertaken with pasture grasses to validate their inclusion. Several other grass viruses that occur in other countries, but have not been looked for in Australia, are potentially important, especially in temperate–Mediterranean pasture grass species. With few exceptions, research on viruses of perennial or annual tropical–subtropical pasture or wild grass species growing within or outside pastures has focussed only on virus identification and characterisation studies, and information on incidences in pastures, losses caused, epidemiology, and management is lacking. Critical research and development gaps that need addressing are identified.

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47

Roget, DK. "Decline in root rot (Rhizoctonia solani AG-8) in wheat in a tillage and rotation experiment at Avon, South Australia". Australian Journal of Experimental Agriculture 35, n. 7 (1995): 1009. http://dx.doi.org/10.1071/ea9951009.

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Studies of a tillage x rotation field experiment begun in 1978 at Avon, South Australia, have demonstrated a decline in rhizoctonia root rot of wheat. In direct-drilled treatments the severity of rhizoctonia root rot culminated in 1983, with patches of poor plant growth accounting for up to 46% of the crop area, and then declined to negligible levels by 1990. Disease severity was significantly less in cultivated than direct-drilled treatments. In cultivated treatments the onset of decline was more difficult to determine, but by 1990 there was negligible rhizoctonia root rot in either tillage treatment, with no increase in disease from 1990 to 1994. Decline in rhizoctonia root rot occurred largely independent of rotation, although there were significant differences in root damage and patch area between rotations, with disease generally being more severe in wheat following pasture than following peas, medic, or wheat. When inoculum of R. solani was added to soil collected from the experimental site in 1985, wheat grown in soil from direct-drilled plots had significantly less disease than wheat grown in soil from cultivated treatments, indicating a possible development of suppression.

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48

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.

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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.

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49

Niu, Yining, Guangdi Li, Lingling Li, K. Yin Chan e Albert Oates. "Sheep camping influences soil properties and pasture production in an acidic soil of New South Wales, Australia". Canadian Journal of Soil Science 89, n. 2 (1 maggio 2009): 235–44. http://dx.doi.org/10.4141/cjss08004.

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This paper reports sheep camping influences on soil chemical and physical properties, and pasture dry matter (DM) production of an acidic soil on the southwest slopes of New South Wales, Australia. The experiment was conducted in the spring (October-November) of 2005 on a long-term field experimental site after 13 yr of rotational grazing. The factors considered were sheep camping (distance from the camping site), pasture type (perennial vs. annual pastures) and lime application (limed vs. unlimed treatments). Over 13 yr of rotational grazing, significant amounts of carbon (C), nitrogen (N), phosphorus (P) and potassium (K) were deposited near the sheep camping site via the deposition of animal excreta. Total C increased from 32.8 g kg-1 20 m away from the camping site to 41.9 g kg-1 at the camping site in 0-5 cm soil depth. The Colwell P increased from 44.0 to 125.9 mg kg-1 from the non-camping area to the camping site in 0-5 cm soil depth. The most interesting result from the current study is that soil bulk density decreased as the intensity of camping increased. On the perennial pastures, soil bulk density was 0.96 and 1.34 g cm-3 at the camping site in the 0-5 and 5-10 cm soil depths, respectively, whereas soil bulk density was 1.14 and 1.39 g cm-3 at 20 m away from the camping site at the corresponding soil depths. Across pasture types, mean pasture DM was highest at the camping site (7.3 and 6.6 t ha-1 for the limed and unlimed pastures, respectively), and lowest 20 m away from the camping site (5.4 and 4.5 t ha-1 for the limed and unlimed pastures, respectively). The vigorous pasture growth and high organic matter at the camping site may have had a "cushioning effect", thereby reducing soil compaction. However, this camping effect was confined to within 5 m of the camping site. It is concluded that sheep camping can create spatial heterogeneity in soil chemical and physical properties. The non-uniform influence on pasture productivity and composition could be minimised by altering the grazing management strategies, such as periodic relocation of the site of shelter, or further subdivision of the grazing paddock, if necessary. Key words: Soil carbon, nitrogen, phosphorus, bulk density, grazing management

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50

Doyle, PT, RA Love e TW Plaisted. "Mineral supplementation and wool production of young Merino sheep on the south coast of Western Australia". Australian Journal of Experimental Agriculture 35, n. 4 (1995): 437. http://dx.doi.org/10.1071/ea9950437.

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Wool-free liveweight change (LWC), wool growth rate, annual wool production, and wool characteristics of young Merino wethers fed supplements of lupins with gypsum or a multi-element mineral lick were examined in 12 experiments at 5 farms between 1989 and 1992. The source of sheep varied between experiments; age was 4.5-6.5 months and liveweight 28-37 kg at the beginning of supplementation. Sheep were fed lupins, lupins coated with gypsum (15-20 g/kg lupins), or lupins along with access to the mineral lick (offered at 140 g/sheep.week). The amount of lupins offered in all treatments within any experiment was the same. Supplementary feeding varied between experiments from 150 to 240 days. The sheep grazed annual pastures at stocking rates of 8-1 6.7ha. Average lick intake was 12-18 g/sheep. day. During supplementary feeding, there was considerable variation in LWC (-80 to +110 g/day) and clean wool growth rates (3.8-15.1 g/day) within and between experiments. However, there was no significant positive effect of gypsum or mineral lick supplementation on LWC or clean wool growth rates during or after supplementary feeding in any experiment. There were positive (P<0.01) relationships between LWC and clean wool growth rates during supplementation. Also, for some spring-shorn sheep types, staple strength of wool was linearly related (P<0.01) to LWC in the period before the position of break in the wool staple. Annual wool production, average fibre diameter, and staple strength of midside wool were not significantly increased by supplements of gypsum or mineral lick in any experiment.

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