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1
Simpson, Stuart L., Rob W. Fitzpatrick, Paul Shand, Brad M. Angel, David A. Spadaro e Luke Mosley. "Climate-driven mobilisation of acid and metals from acid sulfate soils". Marine and Freshwater Research 61, n. 1 (2010): 129. http://dx.doi.org/10.1071/mf09066.
Testo completoAbstract (sommario):
The recent drought in south-eastern Australia has exposed to air, large areas of acid sulfate soils within the River Murray system. Oxidation of these soils has the potential to release acidity, nutrients and metals. The present study investigated the mobilisation of these substances following the rewetting of dried soils with River Murray water. Trace metal concentrations were at background levels in most soils. During 24-h mobilisation tests, the water pH was effectively buffered to the pH of the soil. The release of nutrients was low. Metal release was rapid and the dissolved concentrations of many metals exceeded the Australian water quality guidelines (WQGs) in most tests. The concentrations of dissolved Al, Cu and Zn were often greater than 100× the WQGs and strong relationships existed between dissolved metal release and soil pH. Attenuation of dissolved metal concentrations through co-precipitation and adsorption to Al and Fe precipitates was an important process during mixing of acidic, metal-rich waters with River Murray water. The study demonstrated that the rewetting of dried acid sulfate soils may release significant quantities of metals and a high level of land and water management is required to counter the effects of such climate change events.
2
McBeath, T. M., R. D. Armstrong, E. Lombi, M. J. McLaughlin e R. E. Holloway. "Responsiveness of wheat (Triticum aestivum) to liquid and granular phosphorus fertilisers in southern Australian soils". Soil Research 43, n. 2 (2005): 203. http://dx.doi.org/10.1071/sr04066.
Testo completoAbstract (sommario):
Recent field trials on alkaline soils in southern Australia showed significant grain yield responses to liquid compared with traditional granular forms of P fertiliser. However the advantages of liquid over granular P forms of fertiliser has not been consistent on all soil types. In order to better predict the soil types on which liquid P fertilisers are likely to have potential, a glasshouse trial was conducted to compare the responsiveness of wheat to both liquid and granular forms of P on a wide range of Australian soils. A granular P fertiliser (triple superphosphate) and 2 liquid fertilisers (phosphoric acid and ammonium polyphosphate) were compared at a rate equivalent to 12 kg P/ha in 29 soils representing many of the soil types used for grain production in Victoria and South Australia. Wheat biomass was enhanced by P application in 86% of the soils tested. In 62% of the P-responsive soils, wheat dry matter was significantly greater when liquid P fertilisers were used compared with the granular form. Chemical analysis of the soils tested showed that the better performance of liquid P forms was not correlated to total P concentration in soil, P buffer capacity, or P availability as measured by Colwell-P. However, there was a significant positive relationship between calcium carbonate (CaCO3) content of soil and wheat responsiveness to liquid P fertiliser.
3
Krishnamurti, G. S. R., e R. Naidu. "Speciation and phytoavailability of cadmium in selected surface soils of South Australia". Soil Research 38, n. 5 (2000): 991. http://dx.doi.org/10.1071/sr99129.
Testo completoAbstract (sommario):
A modified sequential extraction scheme was developed for partitioning the particulate-bound cadmium (Cd) into 9 fractions: exchangeable, carbonate-bound/specifically adsorbed, metal–fulvic acid-complex-bound, metal–humic acid-complex-bound, easily reducible metal oxide-bound, organic-bound, amorphous mineral colloid-bound, crystalline Fe oxide-bound, and detrital (bound to mineral lattices). Results on 11 surface soils showed that Cd in these soils was predominantly present in detrital form, bound to the mineral lattices, accounting for 15.8–61.9%, with an average of 33.4%, of the total Cd in the soils. The average relative abundance of Cd bound to the different particulate forms in the soils is in the order: detrital (0.077 mg/kg) > specifically adsorbed/carbonate-bound (0.066 mg/kg) > organic-bound (0.033 mg/kg) > metal–fulvic acid-complex-bound (0.031 mg/kg) > easily reducible metal oxide-bound (0.019 mg/kg) > exchangeable (0.013 mg/kg) > metal–humic acid-complex-bound (0.011 mg/kg) > crystalline Fe oxide-bound (0.001 mg/kg) =amorphous mineral colloid-bound (0.001 mg/kg). The phytoavailable Cd content was determined as Cd concentration in the shoot and leaf of durum wheat plants grown on the soils in a greenhouse study. Statistical treatment of the data showed that the exchangeable Cd (r = 0.735, P = 0.01) and the metal–fulvic acid-complex-bound Cd (r = 0.824, P = 0.002) correlated significantly with the plant-available Cd, compared with other species. The exchangeable and fulvic acid fraction of the metal–organic-complex-bound Cd contents, together, could explain 91.5% of the variation in plant-available Cd, determined as Cd concentration in leaf and stem of the durum wheat plants (r = 0.956, P = 0.0001). The significance of metal–fulvic acid complexes on Cd phytoavailability has not been reported so far and needs in-depth research in explaining the toxicity and food chain contamination of Cd in the environment.
4
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.
Testo completoAbstract (sommario):
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.
5
Singh, Balwant, I. O. A. Odeh e A. B. McBratney. "Acid buffering capacity and potential acidification of cotton soils in northern New South Wales". Soil Research 41, n. 5 (2003): 875. http://dx.doi.org/10.1071/sr02036.
Testo completoAbstract (sommario):
Soil acidity has been of major concern in Australia since European settlement. Acidification processes have been accelerated due to agricultural activities such as N fertiliser application and leguminous N-fixation in farm rotations. In this paper, we measured the acid buffering capacity (pHBC) of Vertosols, soils used predominantly for growing cotton in northern New South Wales. The pHBC values were used to calculate decrease in soil pH assuming net acid input due to agricultural practices. We combined the acidification results with geostatistics to spatially simulate the decline in soil pH of surface soils over time. The results indicate that it would take 10–417 years for soil pH to decrease by 1 unit on an assumed acid input of 5�kmol�H+/ha.year. Soil pH will drop by 1 unit within 100 years for 90% of the soils and within 15 years for 10% of the soils. This reflects the variability of the pHBC for the studied soils. In 50 years from present, most of the eastern and north-western parts of the study region may become highly acidic with soil pH declining to 5.5. There may be a potential threat to sustainable agriculture from acidification in the region, although more work needs to be done to corroborate the counter-effects of water fluxes and carbonate dissolution. Sensitivity analysis indicates that even at low levels of acid input, some areas in the study region may experience significant decline in soil pH in the surface layer.
6
Doolette, Ashlea L., Ronald J. Smernik e Timothy I. McLaren. "The composition of organic phosphorus in soils of the Snowy Mountains region of south-eastern Australia". Soil Research 55, n. 1 (2017): 10. http://dx.doi.org/10.1071/sr16058.
Testo completoAbstract (sommario):
Few studies have considered the influence of climate on organic phosphorus (P) speciation in soils. We used sodium hydroxide–ethylenediaminetetra-acetic acid (NaOH–EDTA) soil extractions and solution 31P nuclear magnetic resonance spectroscopy to investigate the soil P composition of five alpine and sub-alpine soils. The aim was to compare the P speciation of this set of soils with those of soils typically reported in the literature from other cold and wet locations, as well as those of other Australian soils from warmer and drier environments. For all alpine and sub-alpine soils, the majority of P detected was in an organic form (54–66% of total NaOH–EDTA extractable P). Phosphomonoesters comprised the largest pool of extractable organic P (83–100%) with prominent peaks assigned to myo- and scyllo-inositol hexakisphosphate (IP6), although trace amounts of the neo- and d-chiro-IP6 stereoisomers were also present. Phosphonates were identified in the soils from the coldest and wettest locations; α- and β-glycerophosphate and mononucleotides were minor components of organic P in all soils. The composition of organic P in these soils contrasts with that reported previously for Australian soils from warm, dry environments where inositol phosphate (IP6) peaks were less dominant or absent and humic-P and α- and β-glycerophosphate were proportionally larger components of organic P. Instead, the soil organic P composition exhibited similarities to soils from other cold, wet environments. This provides preliminary evidence that climate is a key driver in the variation of organic P speciation in soils.
7
Gerritse, RG. "Simulation of phosphate leaching in acid sandy soils". Soil Research 27, n. 1 (1989): 55. http://dx.doi.org/10.1071/sr9890055.
Testo completoAbstract (sommario):
Prediction of changes in amounts of phosphate leaching from soils with changes in management practices requires a detailed knowledge of the adsorption and desorption characteristics of the soils for phosphate. Non-equilibrium soil distribution of inorganic phosphate was determined at various rates of flow from time courses of phosphate in the leachates of small columns of sandy soils sampled from the Swan Coastal Plain in south-west Western Australia. Equilibrium distribution isotherms were estimated by extrapolating to zero rate of flow. Time courses of phosphate concentrations in the leachates were also calculated with a numerical compartmental simulation model. First-order transport rate equations with time-dependent rate coefficients adequately described the experimental time courses of the leachate concentrations. Kinetic parameters were based on a consideration of the physical/chemical distribution of ortho-phosphate only. The error due to this approach was evaluated by measuring the (biochemical) fixation of phosphate in soil organic matter.
8
Wong, M. T. F., R. W. Bell e K. Frost. "Mapping boron deficiency risk in soils of south-west Western Australia using a weight of evidence model". Soil Research 43, n. 7 (2005): 811. http://dx.doi.org/10.1071/sr05022.
Testo completoAbstract (sommario):
The aim of this work was to develop a risk map for boron (B) deficiency in the grain cropping regions of Western Australia (WA), whilst avoiding the high costs associated with direct B measurements for an area as vast as the south-west of WA. The study firstly determined relationships between 0.01 m CaCl2-extractable soil B levels and readily available data on soil properties and parent materials for Reference Soils of south-west Australia and secondly assembled direct evidence of B deficiency risk from surveys of farmers’ crops and soils and from glasshouse experiments. Across 73 Reference Soils, there was a positive relationship between 0.01 m CaCl2-extractable soil B levels and clay (r 2 = 0.50) and pH (r 2 = 0.43) in the surface horizon. Soils containing <0.5 mg B/kg generally had <5% clay and pH CaCl2 <5.5. Plant and soil analysis surveys in farmers’ fields revealed 10–20% of fields had B levels below tentative critical levels. In a glasshouse experiment, B response in oilseed rape was obtained in 4 sandy acid soils, all developed on sandstone parent materials. From this prior evidence of B deficiency, spatial data layers for surface soil pH, subsurface pH, surface clay level, and geology in south-western Australia were weighted and combined using the Dempster-Shafer weight of evidence model to map B-deficiency risk. The weightings of evidence layers were revised to increase the correspondence between predicted areas of high risk and field areas with measured low B or B deficiency from a validation dataset. The model helps overcome the high cost associated with direct B measurements for risk mapping. A similar approach may have value for mapping risk of other deficiencies of relevance to agriculture.
9
Li, G. D., G. M. Lodge, G. A. Moore, A. D. Craig, B. S. Dear, S. P. Boschma, T. O. Albertsen et al. "Evaluation of perennial pasture legumes and herbs to identify species with high herbage production and persistence in mixed farming zones in southern Australia". Australian Journal of Experimental Agriculture 48, n. 4 (2008): 449. http://dx.doi.org/10.1071/ea07108.
Testo completoAbstract (sommario):
Ninety-one perennial legumes and herbs (entries) from 47 species in 21 genera were evaluated at sites in New South Wales, South Australia and Western Australia over 3 years from 2002 to 2005 to identify plants with superior herbage production, persistence and the potential to reduce ground water recharge. Evaluation was undertaken in three nurseries (general, waterlogged soil and acid soil). Medicago sativa L. subsp. sativa (lucerne) cv. Sceptre was the best performing species across all sites. In the general and acid soil nurseries, Cichorium intybus L. (chicory) cv. Grasslands Puna was the only species comparable with Sceptre lucerne in terms of persistence and herbage production. Trifolium fragiferum L. cv. Palestine and Lotus corniculatus L. SA833 were the best performing species on heavy clay soils prone to waterlogging. Three Dorycnium hirsutum (L.) Ser. accessions persisted well on acid soils, but were slow to establish. Short-lived perennial forage legumes, such as Onobrychis viciifolia Scop. cv. Othello, and three Hedysarum coronarium L. entries, including cv. Grasslands Aokou, had high herbage production in the first 2 years and may be suitable for short-term pastures in phased pasture-crop farming systems. T. uniflorum L. and M. sativa subsp. caerulea SA38052 were highly persistent and could play a role as companion species in mixtures or ground cover species for undulating landscapes. Cullen australasicum (Schltdl.) G.W. Grimes SA4966 and Lotononis bainesii Baker cv. Miles had poor establishment, but were persistent. Chicory, T. fragiferum and L. corniculatus were identified as species, other than lucerne, with the most immediate potential for further selection to increase the diversity of perennial legumes and herbs adapted to southern Australian environments.
10
Walker, PH. "Contributions to the understanding of soil and landscape relationships". Soil Research 27, n. 4 (1989): 589. http://dx.doi.org/10.1071/sr9890589.
Testo completoAbstract (sommario):
A new approach to pedology was developed in Australia in the 1950's. It was based on geomorphic and stratigraphic principles and recognized the cyclic or episodic nature of soil and landscape development. The research reviewed here represents a contribution to that approach and further developments of it in fluvial erosional and depositional landscapes of south-eastern Australia and in glaciated landscapes of midwestern U.S.A. This research features detailed studies of hillslope layers and their relationship to alluvial valley fills; soil chronosequences on flights of alluvial terraces; the stratigraphy of coastal flood plains and the development of acid sulfate soils; dust accession in soils and the resulting problems of interpreting pedogenesis; the erosional-depositional origin of soils in enclosed drainage basins on glacial deposits of Iowa, U.S.A.; the development of a raintower-tilting flume facility and its use in elucidating the processes of soil erosion by flowing water.
11
Hollaway, K. L., R. S. Kookana, D. M. Noy, J. G. Smith e N. Wilhelm. "Crop damage caused by residual acetolactate synthase herbicides in the soils of south-eastern Australia". Australian Journal of Experimental Agriculture 46, n. 10 (2006): 1323. http://dx.doi.org/10.1071/ea05053.
Testo completoAbstract (sommario):
Grain growers in south-eastern Australia have reported unexpected crop failures with theoretically safe recropping periods for acetolactate synthase herbicides in alkaline soils. This experience has led to the concern that these herbicides may degrade very slowly in alkaline soils, and herbicide residues have at times been blamed for unexplained crop losses. To address this issue, we established 5 recropping trials across Victoria and South Australia with 5 acetolactate synthase herbicides (chlorsulfuron, triasulfuron, metsulfuron-methyl, imazethapyr, and flumetsulam). The herbicides were applied to separate plots in years 1, 2 or 3, and sensitive crop species were sown in year 4 to measure the impact of herbicide residues. We observed that the persistence of the sulfonylureas (chlorsulfuron, triasulfuron, metsulfuron-methyl) varied between herbicides, but all persisted longer in alkaline soils than in acid soils, and were, therefore, more likely to damage crops in alkaline soil. Imazethapyr persisted longer in clay soils than in sandy soils and was, therefore, more likely to damage crops in clay soils. All herbicides persisted longer when rainfall was below average. Canola was more sensitive to imazethapyr than either pea, lentil or medic, but was less sensitive to the sulfonylureas. In contrast, lentil and medic were the most sensitive to sulfonylureas. Despite some damage, we found that safe recropping periods could be predicted from the product labels in all but one situation. The sole exception was that metsulfuron-methyl reduced dry matter and yield of lentil and medic sown 10 months after application in a soil with pH 8.5. We hypothesise that the real cause of crop failure in many situations is not unusual herbicide persistence, but failure to take full account of soil type (pH and clay content including variation in the paddock) and rainfall when deciding to recrop after using acetolactate synthase herbicides.
12
Webb, Ashley A., Georgina L. Kelly e Warwick J. Dougherty. "Soil governance in the agricultural landscapes of New South Wales, Australia". International Journal of Rural Law and Policy, n. 1 (29 marzo 2015): 1–16. http://dx.doi.org/10.5130/ijrlp.i1.2015.4169.
Testo completoAbstract (sommario):
Soil is a valuable natural resource. In the state of New South Wales, Australia, the governance of soil has evolved since Federation in 1901. Following rapid agricultural development, and in the face of widespread soil degradation, the establishment of the Soil Conservation Service marked a turning point in the management of soil. Throughout the 20th century, advances in knowledge were translated into evolving governance frameworks that were largely reactionary but saw progressive reforms such as water pollution legislation and case studies of catchment-scale land and vegetation management. In the 21st century, significant reforms have embedded sustainable use of agricultural soils within catchment- and landscape-scale legislative and institutional frameworks. What is clear, however, is that a multitude of governance strategies and models are utilised in NSW. No single governance model is applicable to all situations because it is necessary to combine elements of several different mechanisms or instruments to achieve the most desired outcomes. Where an industry, such as the sugar industry, has taken ownership of an issue such as acid sulfate soil management, self-regulation has proven to be extremely effective. In the case of co-managing agricultural soils with other landuses, such as mining, petroleum exploration and urban development, regulation, compliance and enforcement mechanisms have been preferred. Institutional arrangements in the form of independent commissioners have also played a role. At the landscape or total catchment level, it is clear that a mix of mechanisms is required. Fundamental, however, to the successful evolution of soil governance is strategic investment in soil research and development that informs the ongoing productive use of agricultural landscapes while preventing land degradation or adverse environmental effects.
13
Li, Guangdi D., Rajinder P. Singh, John P. Brennan e Keith R. Helyar. "A financial analysis of lime application in a long-term agronomic experiment on the south-western slopes of New South Wales". Crop and Pasture Science 61, n. 1 (2010): 12. http://dx.doi.org/10.1071/cp09103.
Testo completoAbstract (sommario):
Management of Acid Soils Through Efficient Rotations (MASTER) is a long-term agronomic experiment commenced in 1992. There were 3 fundamental treatment contrasts in this experiment: (a) annual systems v. perennial systems; (b) limed v. unlimed treatments; and (c) permanent pastures v. pasture–crop rotations. The soil was acidic to depth with pH (in CaCl2) below 4.5 and exchangeable Al above 40% at 0.10–0.20 m when the experiment started. Lime was applied every 6 years to maintain soil pHCa at 5.5 in the 0–0.10 m soil depth. A financial analysis was undertaken to estimate potential benefits and costs involved in liming acid soils on the south-western slopes of New South Wales, based on data from the MASTER experiment. The most important finding from the current study is that liming pastures on soils that have a subsurface acidity problem is profitable over the long-term for productive livestock enterprises. The pay-back period for liming pastures, grazed by Merino wethers, was 14 years for both annual and perennial pastures. More profitable livestock enterprises, such as prime lambs or growing-out steers, were estimated to reduce the pay-back period. This gives farmers confidence to invest in a long-term liming program to manage highly acid soils in the traditional permanent pasture region of the high-rainfall zone (550–800 mm) of south-eastern Australia. Results from the current study also confirmed that the total financial return from liming is greater if the land is suitable for operation of a pasture–crop rotation system. The positive cash flows generated from cropping in a relatively short time can significantly shorten the pay-back period for the investment in lime. But cropping without liming on soils with subsurface acidity was worse than grazing animals. Crop choice is crucial for the perennial pasture–crop rotation. Inclusion of high-value cash crops, such as canola or a wheat variety with high protein, would lead to a rise in the aggregate benefits over time as the soil fertility improved and soil acidity was gradually ameliorated.
14
Coventry, D. R., W. J. Slattery, V. F. Burnett e G. W. Ganning. "Longevity of wheat yield response to lime in south-eastern Australia". Australian Journal of Experimental Agriculture 37, n. 5 (1997): 571. http://dx.doi.org/10.1071/ea96146.
Testo completoAbstract (sommario):
Summary. A long-term experiment in north-eastern Victoria has been regularly monitored for wheat yield responses to a range of lime and fertiliser treatments, and the soil sampled for acidity attributes. Substantial grain yield increases have been consistently obtained over a period of 12 years with a single lime application. Lime applied at 2.5 t/ha in 1980 was still providing yield increases of 24% with an acid-tolerant wheat (Matong, 1992 season) and 79% with an acid-sensitive wheat (Oxley, 1993 season) relative to no lime treatment. The 2 wheat cultivars responded differently to phosphorus fertiliser, with the acid-sensitive wheat less responsive to phosphorus fertiliser in the absence of lime. The use of a regular lime application applied as a fertiliser (125 kg lime/ha) with the wheat seed gave only a small grain yield increase (8% Matong, 16% Oxley), despite 1 t/ha of lime applied over the 12-year period. Liming the soil at a rate of 2.5 t/ha (1980) initially raised the soil pH by about 1.0 unit and removed most soluble aluminium (0–10 cm). However, after 12 years of crop–pasture rotation after the initial 2.5 t lime/ha treatment the soil pH had declined by 0.7 of a pH unit and exchangeable aluminium was substantially increased, almost to levels prior to the initial application of lime. Given the continued yield responsiveness obtained following the initial application of lime, this practice, rather than regular applications of small amounts of lime, is recommended for wheat production on strongly acidic (pHw < 5.5) soils in south-eastern Australia.
15
Scott, B. J., A. M. Ridley e M. K. Conyers. "Management of soil acidity in long-term pastures of south-eastern Australia: a review". Australian Journal of Experimental Agriculture 40, n. 8 (2000): 1173. http://dx.doi.org/10.1071/ea00014.
Testo completoAbstract (sommario):
Acidification of non arable soils under long-term pasture presents a major agricultural problem in the high rainfall areas (≥600 mm/year) of central and southern New South Wales and north-eastern Victoria. Some of these soils were already strongly acid to depth before agriculture. Evidence suggests that persistence of pasture species tolerant of acidic soils is being affected adversely on a number of severely acidic soils. Acidification processes are well understood but the capacity for grazing enterprises to pay for amendment by lime application is a major constraint in long-term pasture areas. In addition, soil acidification is likely to have substantial off-site effects on water quantity and quality and as a result, on dryland salinity. However, there is a paucity of scientific evidence to link soil acidity and dryland salinity in this way. Production from a grazing enterprise can be maintained by selecting plants for tolerance of acidity, surface application of lime or a combination of both. Responses by subterranean clover, lucerne and perennial grass (mainly phalaris and cocksfoot)-based pastures to incorporated lime are reported, but there is limited evidence of responses to surface applied lime. The movement of the lime effect into the soil from surface application is suggested as a major factor in controlling lime responses by plants. There is a need for more confidence in the benefits of topdressed lime in non arable soils before producers are likely to adopt the practice. High subsurface acidity in many soils is a major limitation to the range of species that can be grown. In the longer term, the use of lime may remove constraints on the use of productive species such as lucerne. Other options for acidic soils where slope is less than 10% are for the grazing system to be modified or intensified, or for crop or horticultural production. Costs of lime could be justified through more profitable enterprises than traditional grazing operations. Low input systems based on native grasses are intrinsically appealing, however, this is only possible where a premium is paid for such produce (such as super fine wool). Forestry is an option where suitable land and infrastructure are present and should slow soil acidification and minimise off-site impacts. Land retirement may be a useful option for some parts of the landscape that contribute disproportionately to environmental problems. Private and government funded land retirement may have a role to play.
16
Poch, R. M., B. P. Thomas, R. W. Fitzpatrick e R. H. Merry. "Micromorphological evidence for mineral weathering pathways in a coastal acid sulfate soil sequence with Mediterranean-type climate, South Australia". Soil Research 47, n. 4 (2009): 403. http://dx.doi.org/10.1071/sr07015.
Testo completoAbstract (sommario):
Soil micromorphology, using light microscopy and scanning electron microscopy (SEM), was used to describe detailed soil morphological and compositional changes and determine mineral weathering pathways in acid sulfate soils (ASS) from the following 2 contrasting coastal environments in Barker Inlet, South Australia: (i) a tidal mangrove forest with sulfidic material at St Kilda, and (ii) a former supratidal samphire area at Gillman that was drained in 1954 causing sulfuric material to form from sulfidic material. Pyrite framboids and cubes were identified in sulfidic material from both sites and are associated with sapric and hemic materials. Gypsum crystals, interpreted as a product of sulfide oxidation, were observed to have formed in lenticular voids within organic matter in the tidal mangrove soils at St Kilda. Sulfide oxidation was extensive in the drained soil at Gillman, evidenced by the formation of iron oxyhydroxide pseudomorphs (goethite crystallites and framboids) after pyrite and jarosite, and of gypsum crystals. Gypsum crystals occur where a local source of calcium such as shells or calcareous sand is present. Sporadic oxidation episodes are indicated by the formation of iron oxide and jarosite coatings around coarse biogenic voids. These observations indicate that mineral transformation pathways are strongly influenced by soil physico-chemical characteristics (i.e. oxidation rate, Eh, pH, soil solution chemistry, mineralogy, and spatial distribution of sulfides). This information has been used to illustrate the interrelationships of pyrite, carbonate, gypsum, jarosite, and organic matter and help predict soil evolution under changing hydro-geochemical, redoximorphic, and thermal conditions in soils from coastal environments.
17
Culvenor, R. A., e R. J. Simpson. "Persistence traits in perennial pasture grasses: the case of phalaris (Phalaris aquatica L.)". Crop and Pasture Science 65, n. 11 (2014): 1165. http://dx.doi.org/10.1071/cp13333.
Testo completoAbstract (sommario):
Persistence is consistently claimed by Australian farmers as a high priority for perennial grasses in long-term pastures. Phalaris (Phalaris aquatica L.) is a productive perennial grass with proven persistence in south-eastern Australia. Nevertheless, factors that determine the persistence of pasture species in southern Australia related to climate (drought), soil (acidity), grazing pressure, and, importantly, their interaction can reduce persistence of phalaris and other species in various situations. These factors and their interactions are discussed in this review, and strategies to improve persistence with emphasis on plant breeding approaches are considered, with the most durable outcomes achieved when breeding and management options are employed concurrently. Two examples of breeding to improve persistence traits in phalaris are described. A program to improve acid-soil tolerance resulted first in the release of cv. Landmaster, and recently Advanced AT, which is the most aluminium (Al)-tolerant cultivar of phalaris to date. It was bred by recurrent selection on acid soils in a population containing genes from a related, more Al-tolerant species, P. arundinacea. The higher Al tolerance of cv. Advanced AT is of most benefit in more assured establishment on acid soils under variable moisture conditions and confers improved flexibility of sowing date. Cultivar Holdfast GT was bred to address complaints of poor persistence under heavy grazing by cultivars of the highly productive, winter-active type, since high grazing tolerance is needed to achieve profitable returns from developed pastureland. Evidence of good persistence under grazing for cv. Holdfast GT and possible tradeoffs with productivity are discussed. Maintaining high productivity under a predicted higher incidence of drought stress (climate change) and increasing areas of acid soils presents ongoing challenges for persistence in pastures.
18
Kinsela, Andrew S., Jason K. Reynolds e Mike D. Melville. "Agricultural acid sulfate soils: a potential source of volatile sulfur compounds?" Environmental Chemistry 4, n. 1 (2007): 18. http://dx.doi.org/10.1071/en06071.
Testo completoAbstract (sommario):
Environmental context. Acid sulfate soils are important contributors to global environmental problems. Agricultural acid sulfate soils have recently been shown to emit sulfur dioxide, an important gas in global issues of acid rain, cloud formation and climate change. This emission is surprising because these soils tend to be wet and the gas is extremely water-soluble. The potential origins of this gas are not yet understood within the context of acid sulfate soils. Our new study reports the measurement of two potential precursors of sulfur dioxide, dimethylsulfide and ethanethiol, from both a natural and an agricultural acid sulfate soil in eastern Australia. Abstract. Most agricultural soils are generally considered to be a sink for sulfur gases rather than a source; however, recent studies have shown significant emissions of sulfur dioxide and hydrogen sulfide from acid sulfate soils. In the current study, acid sulfate soil samples were taken in northern New South Wales from under sugarcane cropping, as well as from an undisturbed nature reserve. Using gas chromatography/flame photometric detection in conjunction with headspace solid-phase microextraction, we have now determined that these soils are a potential source of the low molecular weight volatile sulfur compounds, dimethylsulfide and ethanethiol. Although the mechanism for their production remains unclear, both compounds are important in the transfer and interconversions of atmospheric and terrestrial sulfur. Therefore, these novel findings have important implications for refining local and regional atmospheric sulfur budgets, as well as for expanding our understanding of sulfur cycling within acid sulfate soils and other sediments.
19
French, Robert J., e Bevan J. Buirchell. "Lupin: the largest grain legume crop in Western Australia, its adaptation and improvement through plant breeding". Australian Journal of Agricultural Research 56, n. 11 (2005): 1169. http://dx.doi.org/10.1071/ar05088.
Testo completoAbstract (sommario):
Between 500 000 and 1 000 000 tonnes of narrow-leafed lupins (Lupinus angustifolius L.) are produced in Western Australia each year. It has become the predominant grain legume in Western Australian agriculture because it is peculiarly well adapted to acid sandy soils and the Mediterranean climate of south-western Australia. It has a deep root system and root growth is not reduced in mildly acid soils, which allows it to fully exploit the water and nutrients in the deep acid sandplain soils that cover much of the agricultural areas of Western Australia. It copes with seasonal drought through drought escape and dehydration postponement. Drought escape is lupin’s main adaptation to drought, and has been strengthened by plant breeders over the past 40 years by removal of the vernalisation requirement for flowering, and further selection for earlier flowering and maturity. Lupin postpones dehydration by several mechanisms. Its deep root system allows it to draw on water from deep in the soil profile. Lupin stomata close to reduce crop water demand at a higher leaf water potential than wheat, but photosynthetic rates are higher when well watered. It has been proposed that stomata close in response to roots sensing receding soil moisture, possibly at a critical water potential at the root surface. This is an adaptation to sandy soils, which hold a greater proportion of their water at high matric potentials than loamy or clayey soils, since the crop needs to moderate its water use while there is still sufficient soil water left to complete its life cycle. Lupin has limited capacity for osmotic adjustment, and does not tolerate dehydration as well as other crops such as wheat or chickpea. Plant breeding has increased the yield potential of lupin in the main lupin growing areas of Western Australia by 2–3 fold since the first adapted cultivar was released in 1967. This has been due largely to selecting earlier flowering and maturing cultivars, but also to improved pod set and retention, resistance to Phomopsis leptostromiformis (Kühn) Bubák, and more rapid seed filling. We propose a model for reproductive development in lupin where vegetative growth is terminated in response to receding soil moisture and followed by a period in which all assimilate is devoted to seed filling. This should allow lupin to adjust its developmental pattern in response to seasonal conditions to something like the optimum that mathematical optimal control theory would choose for that season. This is the type of pattern that has evolved in lupin, and the task of future plant breeders will be to fine-tune it to better suit the environment in the lupin growing areas of Western Australia.
20
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.
Testo completoAbstract (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.
21
Bibi, Irshad, Balwant Singh e Ewen Silvester. "Akaganéite (β-FeOOH) precipitation in inland acid sulfate soils of south-western New South Wales (NSW), Australia". Geochimica et Cosmochimica Acta 75, n. 21 (novembre 2011): 6429–38. http://dx.doi.org/10.1016/j.gca.2011.08.019.
Testo completo
22
Hodge, TJV, e DC Lewis. "A description of acid soils and the relationships between properties of acid soils and the nutrient status of grazed pastures in the southeast of South Australia". Soil Research 27, n. 1 (1989): 149. http://dx.doi.org/10.1071/sr9890149.
Testo completoAbstract (sommario):
Areas of low soil pH in the south-east of South Australia were delineated by using previously submitted soil samples and soil association maps. A survey was then undertaken in the major soil associations to determine the severity and characteristics of highly acid soils. The acid soil types identified were a siliceous sand over clay (Db/Dy) and a siliceous sand over organic matter/sesquioxide pan (Uc). The top 2.5 cm of both soil types was significantly less acid than the remaining portion of the A horizon, with pH decreasing rapidly with depth until the B horizon, where a substantial soil pH increase occurred. As soil pH (0.01 M CaCl2) decreased below 4.5, extractable soil aluminium (0.01 M CaCl2) increased rapidly, to a maximum extractable concentration of 17 �g g-l. These soil types were also found to be deficient in both phosphorus and potassium, with 65% of the sites having extractable phosphorus concentrations below the critical value of 20 �g g-1 and 35% below the critical value for extractable potassium of 80 �g g-l. For subterranean clover, significant positive correlations were observed between soil pH and plant calcium and sulfur, and between extractable soil aluminium and plant aluminium. Significant negative correlations were observed between soil pH and plant manganese and between extractable soil aluminium and plant calcium and magnesium. For ryegrass, significant positive correlations were observed between extractable soil aluminium and plant aluminium and manganese. Significant negative correlations were observed between soil pH and plant manganese and between extractable soil aluminium and plant calcium. No other significant correlations were obtained. The results are discussed in relation to further acidification and management of these acid siliceous sands.
23
Li, G. D., K. R. Helyar, M. K. Conyers, B. R. Cullis, P. D. Cregan, R. P. Fisher, L. J. C. Castleman, G. J. Poile, C. M. Evans e B. Braysher. "Crop responses to lime in long-term pasture-crop rotations in a high rainfall area in south-eastern Australia". Australian Journal of Agricultural Research 52, n. 3 (2001): 329. http://dx.doi.org/10.1071/ar00087.
Testo completoAbstract (sommario):
A long-term trial, known as ‘managing acid soils through efficient rotations’ (MASTER), commenced in 1992 to develop and demonstrate a cropping system that is economically viable on the highly acid soils of the traditional permanent pasture region in south-eastern Australia, so that their fertility is sustained or improved. There were 2 permanent pasture systems and 2 pasture–crop rotations, each with and without lime. This paper reports the effect of lime on crop production over the first cycle (6 years). On annual pasture–crop rotations, lime significantly increased the dry matter production at anthesis and grain yields of wheat (cv. Dollarbird) compared with the unlimed treatments. Averaged across years from 1992 to 1997 (excluding the severe drought year 1994), wheat crops produced 1.6 t/ha more grain on the limed treatments than on the unlimed treatments (3.6 v. 2.0 t/ha). On perennial pasture–crop rotations, the lime effects varied with crops grown at each phase and year. For example, despite being tolerant of acidity, oats (cv. Yarran) responded to lime in 1996. Likewise, triticale (cv. Abacus) responded to lime in 1997. Wheat (cv. Dollarbird) that is moderately tolerant to acidity responded to lime in phase 6 from 1992 to 1997 excluding 1994 (3.5 v. 1.7 t/ha). Acid-tolerant wheat varieties, triticale, and narrow-leaf lupins are considered the most viable crops for the soil and climatic conditions encountered in this high rainfall (5000—800 mm per annum) area of south-eastern Australia.
24
McDonald, G. K., J. D. Taylor, A. Verbyla e H. Kuchel. "Assessing the importance of subsoil constraints to yield of wheat and its implications for yield improvement". Crop and Pasture Science 63, n. 12 (2012): 1043. http://dx.doi.org/10.1071/cp12244.
Testo completoAbstract (sommario):
Many of the soils in the Australian cereal belt have subsoils with chemical and physical properties that restrict root growth, which limits water use and yield. On alkaline sodic soils salinity, high pH, high available boron (B), deficiencies of zinc (Zn) and manganese (Mn) and high soil strength occur commonly and aluminium (Al) toxicity restricts root growth on acid soils. While the effects of individual subsoil constraints have been studied there is some debate about the relative importance to yield of the different soil stresses across the region. To address this issue yield variation among a set of 52 varieties of bread wheat was analysed using yield data from 233 trials conducted over 12 years. The trials were conducted in all mainland States but the majority were in South Australia and Western Australia. Each variety was characterised for its response to high B, high pH, Al toxicity, salinity, deficiencies in Zn and Mn and resistance to root lesion nematode (Pratylenchus neglectus), root growth through strong soil, seminal root angle, carbon isotope discrimination (CID) and maturity. This data was then used to examine the contribution of each trait to the genetic variation in yield at each of the 233 trials. The contribution of a specific trait to the genetic variation in yield at each site was used to infer the importance of a particular constraint to yield at that site. Of the traits linked to soil constraints, salinity tolerance, (measured by Na+ exclusion) was most often associated with genetic variation in grain yield (34% of all experiments), followed by tolerance to high Al (26%) and B tolerance (21%). Tolerance to low Zn and Mn were not consistently associated with yield variation. However, maturity was the trait that was most frequently associated with yield variation (51% of experiments), although the relative importance of early and late flowering varied among the States. Yield variation was largely associated with early flowering in Western Australia and the relative importance of late flowering increased as trials moved eastward into South Australia, Victoria and New South Wales. Narrow, rather than wide, seminal root angle was more commonly associated with high yield (25% of sites) and there was little evidence of any regional pattern in the importance of root angle. CID was important in 18% of trials with a low CID being most commonly associated with high yields. The yield advantage at sites where a trait contributed significantly to yield variation ranged from ~15% for Na+ exclusion and B tolerance to 4% for tolerance to high pH. The analysis has provided an assessment of the relative importance of a range of traits associated with adaptation to environments where subsoil constraints are likely to affect yield and has indicated patterns in the importance and effects of these traits that may be linked to regional variation in rainfall and soils.
25
Stępkowski, Tomasz, Lionel Moulin, Agnieszka Krzyżańska, Alison McInnes, Ian J. Law e John Howieson. "European Origin of Bradyrhizobium Populations Infecting Lupins and Serradella in Soils of Western Australia and South Africa". Applied and Environmental Microbiology 71, n. 11 (novembre 2005): 7041–52. http://dx.doi.org/10.1128/aem.71.11.7041-7052.2005.
Testo completoAbstract (sommario):
ABSTRACT We applied a multilocus phylogenetic approach to elucidate the origin of serradella and lupin Bradyrhizobium strains that persist in soils of Western Australia and South Africa. The selected strains belonged to different randomly amplified polymorphic DNA (RAPD)-PCR clusters that were distinct from RAPD clusters of applied inoculant strains. Phylogenetic analyses were performed with nodulation genes (nodA, nodZ, nolL, noeI), housekeeping genes (dnaK, recA, glnII, atpD), and 16S-23S rRNA intergenic transcribed spacer sequences. Housekeeping gene phylogenies revealed that all serradella and Lupinus cosentinii isolates from Western Australia and three of five South African narrow-leaf lupin strains were intermingled with the strains of Bradyrhizobium canariense, forming a well supported branch on each of the trees. All nodA gene sequences of the lupin and serradella bradyrhizobia formed a single branch, referred to as clade II, together with the sequences of other lupin and serradella strains. Similar patterns were detected in nodZ and nolL trees. In contrast, nodA sequences of the strains isolated from native Australian legumes formed either a new branch called clade IV or belonged to clade I or III, whereas their nonsymbiotic genes grouped outside the B. canariense branch. These data suggest that the lupin and serradella strains, including the strains from uncultivated L. cosentinii plants, are descendants of strains that most likely were brought from Europe accidentally with lupin and serradella seeds. The observed dominance of B. canariense strains may be related to this species' adaptation to acid soils common in Western Australia and South Africa and, presumably, to their intrinsic ability to compete for nodulation of lupins and serradella.
26
Pal, Y., R. J. Gilkes e M. T. F. Wong. "Mineral sources of potassium to plants for seven soils from south-western Australia". Soil Research 40, n. 8 (2002): 1357. http://dx.doi.org/10.1071/sr02014.
Testo completoAbstract (sommario):
This investigation was conducted with surface horizon samples from 7 south-western Australian soils and their 3 size fractions (sand, silt, and clay). The K release of these materials was measured for several extractants; the highest amounts of K were released from the clay (<2 μm) fraction. The presence of sand-size feldspars and incomplete removal of attached organic matter resulted in sand releasing significant amounts of K. The proportions of total K released in boiling 1 m HNO3 by the sand, silt, and clay fractions ranged from 0.4 to 3.4%, 2.6 to 36.3%, and 11.2 to 51.4%, respectively, and from 2.0% to 22.9% for the whole soils. Cumulative K uptake by 6 harvests of ryegrass over 260 days ranged from 0.26 to 1.23 cmol/kg soil.The clay fraction released higher proportions of total K to acid compared with the sand and silt size fractions because of the high specific surface area of the clay and because it contained proportionately higher amounts of illite, which releases K by both ion exchange and dissolution, whereas K release from feldspars requires congruent dissolution of the silicate structure. The differences in contents of StepK (relatively available fraction of the non-exchangeable K) and CRK (constant rate K) for 1 m HNO3 dissolution of these soils and size fractions reflect differences in mineralogical composition between the soils and size fractions. The low contents of StepK for the sand fraction indicated that K was strongly retained by feldspars. The soils with high CRK values had significant amounts of illite in the clay fraction. Values of CRK were positively related to cumulative K uptake and cumulative dry matter yield of ryegrass.
27
Mathers, Nicole J., Zhihong Xu, Susan J. Berners-Price, M. C. Senake Perera e Paul G. Saffigna. "Hydrofluoric acid pre-treatment for improving 13C CPMAS NMR spectral quality of forest soils in south-east Queensland, Australia". Soil Research 40, n. 4 (2002): 665. http://dx.doi.org/10.1071/sr01073.
Testo completoAbstract (sommario):
Hydrofluoric acid (HF) was used to pre-treat forest soils of south-east Queensland for assessing the effectiveness of iron (Fe) removal, carbon (C) composition using 13C cross-polarisation (CP) with magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) before and after the HF pre-treatment, and the improvement of 13C CPMAS NMR spectra. Soil samples were collected from 4 experimental sites of different soil types, harvest residue management or prescribed burning, and tree species. More than 86% of Fe was in all soil types removed by the HF treatment. The 13C NMR spectral quality was improved with increased resolution, especially in the alkyl C and O-alkyl C regions, and reduced NMR run-time (1-5�h per sample compared with >20�h per sample without the pre-treatment). The C composition appeared to alter slightly after the pre-treatment, but this might be largely due to improved spectrometer conditions and increased resolution leading to more accurate NMR spectral integration. Organic C recovery after HF pre-treatment varied with soil types and forest management, and soluble soil organic matter (SOM) could be lost during the pre-treatment. The Fourier Transform-Infrared (FT-IR) spectra of HF extracts indicated the preferential removal of carboxylic C groups during the pre-treatment, but this could also be due to adsorbed water on the mineral matter. The NMR spectra revealed some changes in C composition and quality due to residue management and decomposition. Overall, the HF treatment was a useful pre-treatment for obtaining semi-quantitative 13C CPMAS NMR spectra of subtropical Australian forest soils.
28
Blunden, B. G., e B. Indraratna. "Evaluation of surface and groundwater management strategies for drained sulfidic soil using numerical simulation models". Soil Research 38, n. 3 (2000): 569. http://dx.doi.org/10.1071/sr99018.
Testo completoAbstract (sommario):
The effective management of acid sulfate soils is a major issue for many coastal regions in Australia. Simulations were conducted to evaluate 4 different water management strategies that could be applied to agricultural land on the south coast of New South Wales, Australia, to minimise acid generation from acid sulfate soils. The water management strategies are compared with the existing extensively drained situation which generates and discharges large quantities of acidic pyrite oxidation products. The 4 water management strategies include elevated drain water levels using a weir, 25 mm irrigation on a 7- or 14-day cycle, and elevated drain water levels with irrigation. All of these strategies were designed to minimise the generation of acid by reducing the transport of oxygen to the sulfidic soil. Simulations were conducted for weather and site conditions experienced during a 12-month period starting in July 1997. Model simulations showed that maintenance of elevated drain water levels using a weir in the drain significantly reduced the amount of acid generated by 75% and 57%, at 10 and 90 m distance from the drain, respectively, by comparison with the existing drained state. The addition of 25 mm irrigation on a 14-day cycle to the weir simulation reduced the oxidation of pyrite by a further 1–2%. Application of irrigation only on a 7-day cycle also reduced the acid generated by 89% and 94% at 10 and 90 m distance from the drain, respectively, by comparison with the existing drained state. Irrigation on a 14-day cycle was not as successful in reducing pyrite oxidation as either the 7-day irrigation or weir strategies. Evaluation of the 4 water management options showed that significant improvements can be made with respect to the amount of acid generated by relatively simple and cost-effective land management practices.
29
Knowles, T. A., e B. Singh. "Carbon storage in cotton soils of northern New South Wales". Soil Research 41, n. 5 (2003): 889. http://dx.doi.org/10.1071/sr02023.
Testo completoAbstract (sommario):
Soil carbon is an important component of the global carbon cycle with an estimated pool of soil organic carbon of about 1500 Gt. There are few estimates of the pool of inorganic carbon, but it is thought to be approximately 50% of the organic carbon pool. There is no detailed study on the estimation of the soil carbon pool for Australian soils.In order to quantify the carbon pools and to determine the extent of spatial variability in the organic and inorganic carbon pools, 120 soil cores were taken down to a depth of 0.90 m from a typical cotton field in northern NSW. Three cores were also taken from nearby virgin bushland and these samples were used as paired samples. Each soil core was separated into 4 samples, i.e. 0–0.15, 0.15–0.30, 0.30–0.60, and 0.60–0.90 m. Soil organic carbon was determined by wet oxidation and inorganic carbon content was determined using the difference between total carbon and organic carbon, and confirmed by the acid dissolution method. Total carbon was measured using a LECO CHN analyser. Soil organic carbon of the field constituted 62% (0–0.15 m), 58% (0.15–0.30 m), 60% (0.30–0.60 m), and 67% (0.60–0.90 m) of the total soil carbon. The proportion of inorganic carbon in total carbon is higher than the global average of 32%. Organic carbon content was relatively higher in the deeper layers (>0.30�m) of the studied soils (Vertosols) compared with other soil types of Australia. The carbon content varied across the field, however, there was little correlation between the soil types (grey, red, or intergrade colour) and carbon content. The total soil carbon pool of the studied field was estimated to be about 78 t/ha for 0–0.90 m layer, which was approximately 58% of the total soil carbon in the soil under nearby remnant bushland (136 t/ha). The total pool of carbon in the cotton soils of NSW was estimated to be 44.8 Mt C, where organic carbon and inorganic carbon constitute 34.9 Mt C and 9.9 Mt C, respectively. Based on the results of a limited number of paired sites under remnant vegetation, it was estimated that about 18.9 Mt of C has been lost from Vertosols by cotton cropping in NSW. With more sustainable management practices such as conservation tillage and green manuring, some of the lost carbon can be resequestered, which will help to mitigate the greenhouse effect, improve soil quality and may increase crop yield.
30
Culvenor, R. A., J. T. Wood, A. L. Avery, W. Dempsey, S. E. McDonald, G. Ronnfeldt e P. E. Veness. "Multi-site evaluation on acid soils of a Phalaris aquatica × P. arundinacea × P. aquatica backcross population bred for acid soil tolerance". Australian Journal of Agricultural Research 55, n. 6 (2004): 681. http://dx.doi.org/10.1071/ar03262.
Testo completoAbstract (sommario):
Half-sib families in the AT98 Phalaris aquatica × P. arundinacea × P. aquatica backcross population bred for acid soil tolerance were compared for establishment, persistence, and yield with phalaris (P. aquatica L.) controls and cocksfoot (Dactylis glomerata L. cv. Porto) at 4 sites in south-eastern Australia with the aim of selecting the parents of a new cultivar. The sites had strongly acid soils but differed in parent material, pH profile, soil fertility, and suitability for phalaris. Establishment by AT98 was clearly superior to all phalaris controls and similar to cocksfoot in an acid soil high in Al to depth at Chiltern, north-eastern Victoria, after sowing in early spring 2000. It was considered likely that better establishment by AT98 was due to its higher Al tolerance. In contrast, little variation in establishment was observed at 3 other sites sown in late autumn 1999, possibly due to a longer period free of moisture stress compared with the later sown Chiltern site. Once established, the control cultivars of phalaris at the autumn-sown sites in general persisted and yielded similarly to the mean of the AT98 families. Significant family variation was observed and predicted heritability on a family mean basis was high for persistence measured as basal frequency and moderately high for yield in the third year. Family by site interaction was relatively low for both attributes. A cultivar based on the best families should give more reliable establishment on acid soils high in Al under conditions where rapid root growth to depth is needed for survival, and give more flexibility of sowing date on these soils. Its best performance relative to cv. Landmaster in terms of third-year yield was predicted to occur on granite-derived soils in north-eastern Victoria.
31
Sammut, J., I. White e MD Melville. "Acidification of an estuarine tributary in eastern Australia due to drainage of acid sulfate soils". Marine and Freshwater Research 47, n. 5 (1996): 669. http://dx.doi.org/10.1071/mf9960669.
Testo completoAbstract (sommario):
Episodic acidification (pH <5) of estuarine tributaries caused by the oxidation of sulfidic floodplain sediments is widespread in eastern Australia. Drainage and flood mitigation works promote oxidation and the export of sulfuric acid and dissolved aluminium and iron into streams. This paper examines the acidification of a tidal reach on the Richmond River, New South Wales. Acid discharge is controlled by the floodplain water balance, drainage of shallow acid groundwater, and tidal floodgate operation. Floodgates store acid waters for more than six months. Acid discharges ranged from short pulses during light rains to ~950 t of sulfuric acid in a major flood that acidified the reach for over seven weeks. Extensive iron flocs accompanied acidification and coated the benthos. The chemistry of the reach reflected mixing of acid groundwater with upland waters and showed pH-dependent enhancement or depletion of species relative to chloride. Concentrations of monomeric aluminium were over 300 times larger than local (ANZECC) guidelines and 90 km of the river were acidified after floods. The estimated rate of sulfuric acid production from the floodplain is ~300 kg ha-1 year-1 and discharge may occur for over 1000 years. Management options are considered; however, the long-term consequences of acidification of tidal reaches are unknown.
32
Brennan, R. F., M. D. A. Bolland e R. W. Bell. "Increased risk of zinc deficiency in wheat on soils limed to correct soil acidity". Soil Research 43, n. 5 (2005): 647. http://dx.doi.org/10.1071/sr04162.
Testo completoAbstract (sommario):
Addition of lime to ameliorate soil acidity has been observed to induce zinc (Zn) deficiency for wheat in sandy soils of south-western Australia, reducing grain yields. The implications of widespread use of lime to treat acid soils for the residual value of Zn in these soils are not known. In a glasshouse experiment, using a Zn-deficient sand from south-western Australia, 3 levels of finely powdered calcium carbonate were added and incubated in moist soil for 6 weeks at 22°C to produce three different pH values (1 : 5 soil : 0.01 m CaCl2): 4.9 (original soil not treated with calcium carbonate), 5.8, and 7.4. Five amounts of Zn, as solutions of Zn sulfate, were then incubated in moist soil for 0, 30, 60, 120, and 180 days before sowing spring wheat (Triticum aestivum L.). The residual value of the applied Zn was determined using yield of dried shoots, Zn content in dried shoots, and soil test Zn (DTPA extraction). This was done by calculating the effectiveness of the incubated Zn for all 3 soils relative to the effectiveness of Zn applied just before sowing wheat (0 day incubation, freshly applied Zn) for the soil not treated with calcium carbonate. As measured using yield of dried shoots, Zn content of dried shoots, or soil test Zn, the residual value of the incubated Zn decreased with increasing soil pH and with increasing period of incubation of Zn with moist soil before sowing wheat. The critical Zn concentration, associated with 90% of the total yield of dried wheat shoots, was (mg Zn/kg) 13 in the youngest mature growth (apex and youngest emerged leaf), and 20 for rest of dried shoots. These values were similar to current critical values for unlimed soils. The relationship between yield of dried shoots and DTPA soil test Zn was similar for unlimed and limed soils, so similar critical soil test Zn was applicable on the sandy soil regardless of soil pH. Critical DTPA soil test Zn, the soil test Zn that was related to 90% of the maximum yield of dried shoots, was 0.14 mg Zn/mg soil. To combat the increased risk of Zn deficiency on soils limed to ameliorate soil acidity, fertiliser Zn needs to be re-applied to the soil when soil and plant tests indicate a high likelihood of deficiency.
33
Brennan, R. F., e M. D. A. Bolland. "Zinc sulfate is more effective at producing wheat shoots than zinc oxide in an alkaline soil but both sources are equally effective in an acid soil". Australian Journal of Experimental Agriculture 46, n. 12 (2006): 1615. http://dx.doi.org/10.1071/ea05071.
Testo completoAbstract (sommario):
The effectiveness of zinc, as either zinc sulfate (ZnSO4.7H2O, 22.4% Zn) or zinc oxide (ZnO; 80% Zn) applied to an acid sand or an alkaline sandy clay, at producing wheat shoots was compared in a glasshouse experiment using yield of 50-day-old wheat (Triticum aestivum L.) plants. The fertilisers were applied as fine powders and mixed through the soil. Both fertilisers were equally effective in the acid soil, but the oxide was about half as effective as the sulfate in the alkaline soil; about twice the amount of zinc as the oxide was required to produce the same yield as zinc added as the sulfate. The amount of zinc required to produce 90% of the maximum yield was 38 µg Zn/pot for both sources of zinc in the acid soil, and 100 µg Zn/pot for the sulfate source and 250 µg Zn/pot for the oxide source for the alkaline soil. Critical zinc, which is the zinc concentration in the youngest emerged leaf that was related to 90% of the maximum yield of shoots, was about 13 mg/kg for both sources of zinc and both soils. Zinc oxide may be less effective at producing wheat shoots than zinc sulfate in alkaline soils of south-western Australia.
34
Cooper, J. L. "The effect of biosolids on cereals in central New South Wales, Australia. 1. Crop growth and yield". Australian Journal of Experimental Agriculture 45, n. 4 (2005): 435. http://dx.doi.org/10.1071/ea03099.
Testo completoAbstract (sommario):
Two forms of biosolids, with and without lime, were applied to acid soils at 2 sites in central New South Wales. Wheat and triticale were then grown on these sites to determine the effect of biosolids on crop growth and yield. The forms of biosolids used were dewatered sewage sludge cake, and N-Viro Soil which is a lime amended sewage sludge. Dewatered sewage sludge cake was applied at rates of 0, 6, 12 and 24 dry Mg/ha, and N-Viro soil at 0, 1.5, 3.0 and 4.5 dry Mg/ha. Biosolids produced grain yield increases of over 50% at both sites, with the largest yield increases at the highest rate of dewatered sewage sludge. Continued cropping at 1 of the sites showed that significant yield increases were still obtained 3 years after the initial application. The addition of lime and N-Viro Soil raised soil pH, and produced small but long lasting yield increases. However, the main benefit of biosolids seems to have come from the nutrients they supplied rather than changes in soil pH.
35
Diatloff, E., CJ Asher e FW Smith. "Concentrations of rare earth elements in some Australian soils". Soil Research 34, n. 5 (1996): 735. http://dx.doi.org/10.1071/sr9960735.
Testo completoAbstract (sommario):
Total, exchangeable, and soil solution concentrations were measured for 15 rare earth elements (REEs) in 9 soils from Queensland and New South Wales. In a further 10 acid soils, effects of amendment with CaCO3 or CaSO4 . 2H2O were measured on the concentrations of REEs in soil solution. The total concentration of the REEs in soil solutions from unamended soils ranged from below the detection limit (0.007 µM) to 0.64 µM. Lanthanum (La) and cerium (Ce) were the REEs present in the greatest concentrations, the highest concentrations measured in the diverse suite of soils being 0.13 µM La and 0.51 µM Ce. Rare earth elements with higher atomic numbers were present in very low concentrations. Exchangeable REEs accounted for 0.07 to 12.6% of the total REEs measured in the soils. Addition of CaCO3 increased soil solution pH and decreased REE concentrations in soil solution, whilst CaSO4 . 2H2O decreased soil solution pH and increased the concentrations of REEs in soil solution. Solubility calculations suggest that CePO4 may be the phase controlling the concentration of Ce in soil solution.
36
Gilkes, RJ, e JC Hughes. "Sodium-fluoride pH of South-Western Australian soils as an indicator of P-sorption". Soil Research 32, n. 4 (1994): 755. http://dx.doi.org/10.1071/sr9940755.
Testo completoAbstract (sommario):
Phosphate sorption by the surface horizon of 228 acid to neutral Western Australian (W.A.) soils is more closely related (r(2) = 0.76) to the content of oxalate-extractable aluminium than to any other soil constituent. This fraction corresponds to poorly ordered inorganic and organic Al compounds that release considerable amounts of OH- to NaF solution. Thus the abundance of these compounds in soil may be estimated by measurement of the pH of a NaF extract (pH((NaF)) This association enables the rapid and moderately accurate prediction in the field of the P-sorption capacity of soils (r(2) = 0.72) by measuring pH(NaF) With a. simple, portable pH meter. For many W.A. soils, it is probable that well crystalline aluminium and iron oxides, clay minerals and other soil constituents are of secondary importance in determining P-sorption and that most P-sorption is due to poorly ordered and organically complexed forms of Al.
37
Cotching, W. E., S. Lynch e D. B. Kidd. "Dominant soil orders in Tasmania: distribution and selected properties". Soil Research 47, n. 5 (2009): 537. http://dx.doi.org/10.1071/sr08239.
Testo completoAbstract (sommario):
Dermosols (24%) and Organosols (14.8%) are the dominant soil orders in Tasmania, with the mapped occurrence of >985 000 ha of Organosols in Tasmania being the greatest in any Australian State. Tenosols and Rudosols are well represented in all 3 natural resource management (NRM) regions and Kurosols are more prevalent in the NRM North and South Regions. Tasmania has a greater proportion of Ferrosols (8.4%) than the whole of Australia (0.8%) and these soils are some of the most productive in Tasmania with >25 000 ha used for cropping. Hydrosols (3.7%) are probably underestimated. Chromosols (5.3%) and Sodosols (1.6%) are relatively minor soils in Tasmania, occurring predominantly in lower rainfall areas with <800 mm average annual rainfall. Parent material is a strong determinant of soil distribution in Tasmania but many Soil Orders occur on a wide range of parent materials. Brown suborders are predominant in several Soil Orders. A large part of Tasmania (2 658 000 ha) is mapped as being used for conservation, with one-third of this area being mapped as Organosols. The mean surface horizon soil carbon content (4.3%) is relatively high, likely due to Tasmania’s relatively high annual rainfall and cool temperatures. Most Soil Orders have moderately acid surface horizons but soils on calcareous parent materials are neutral to strongly alkaline (Tenosols and Calcarosols). The dataset covers the mainland extent of Tasmania, as well as all large islands around Tasmania’s coastline including King, Flinders, Hunter, Three Hummock, Robbins, Cape Barren, Clarke, and Maria Islands.
38
Barnes, Phoebe, Brian R. Wilson, Chris Nadolny e Ivor Growns. "The influence of individual native trees and grazing regime on soil properties and groundcover patterns in a temperate landscape of New South Wales, Australia". Rangeland Journal 31, n. 4 (2009): 405. http://dx.doi.org/10.1071/rj09017.
Testo completoAbstract (sommario):
Scattered native trees are a significant ecological resource across the agricultural landscape, yet their numbers are declining due to factors such as dieback, senescence and agricultural activity. This study examined the interactions among Eucalyptus melliodora (Cunn. ex Schauer) trees, vegetation composition and selected surface soil chemical properties in grazed and ungrazed paddocks on the Northern Tablelands of New South Wales, Australia. Four farms on granite soils were examined in grazed and ungrazed treatments. Vegetation composition was assessed, and soil samples were collected in plots beneath the canopy and in adjacent open areas in both north and south directions of the tree canopy. Native grasses dominated the vegetation in both beneath the canopy and open areas, at both grazed and ungrazed sites. However, their composition varied between farms. Several C3 and C4 grasses contributed to the groundcover of the canopy and open sites, but C3 grasses were generally more common under the canopy. Significant differences occurred in soil C, N, P and pH, and vegetation composition between canopy and open areas, and between grazed and ungrazed treatments. Soil P, C and N contents in grazed sites were typically similar to or higher than those in ungrazed sites, and soils were less acid in the ungrazed compared with grazed sites. All soil parameters measured were significantly higher under tree canopies, except P. The tree, soil and vegetation factors were strongly related. This study confirms that individual scattered trees create a distinct mosaic of localised soil improvement, and influence vegetation composition so that paddocks with trees are floristically more diverse than paddocks without trees. The results illustrate the potential benefits of retaining trees for both biodiversity values and livestock production in Australia.
39
Graham, S., B. R. Wilson, N. Reid e H. Jones. "Scattered paddock trees, litter chemistry, and surface soil properties in pastures of the New England Tablelands, New South Wales". Soil Research 42, n. 8 (2004): 905. http://dx.doi.org/10.1071/sr03065.
Testo completoAbstract (sommario):
Scattered paddock trees are widespread throughout rural Australia but their effect on soil conditions has received only limited research attention. This study investigated the influence of 3 Eucalyptus species on surface soil properties on different parent materials at both stocked and unstocked sites on the Northern Tablelands of New South Wales. Mineral soil samples to a depth of 5 cm were collected at intervals up to twice the canopy radius away from tree trunks and litter samples were collected at corresponding points. Mineral soils were analysed for pH (CaCl2), organic carbon (C), and extractable phosphorus (P) concentration, while for the litter samples, P, sulfur, cations, and ash alkalinity were determined. Stocking with sheep and cattle increased surface soil acidity and C and P concentrations at each location. However, soils under E. melliodora and E. viminalis showed higher pH and increased C and P concentrations close to the tree stem irrespective of grazing. Soils under E. caliginosa, while having similar patterns of C and P, showed variable acidity patterns with instances of lower pH close to the tree stem. Spatial patterns in soil acidity were associated with the ash alkalinity of litter, indicating litter as a source of alkalinity addition to the soil surface, although different patterns of soil pH could not be fully explained by litter ash alkalinity alone. The close correlation of litter Ca content with ash alkalinity suggests that this element might be a suitable indicator of the acid amelioration capacity of different tree species.
40
Pate, J. S., W. H. Verboom e P. D. Galloway. "Co-occurrence of Proteaceae, laterite and related oligotrophic soils: coincidental associations or causative inter-relationships?" Australian Journal of Botany 49, n. 5 (2001): 529. http://dx.doi.org/10.1071/bt00086.
Testo completoAbstract (sommario):
This communication presents the hypothesis that certain Australian lateritic and related oligotrophic soils may have been partly derived biotically from soluble iron-rich complexes generated following secretion of low-molecular weight organic acids by phosphate-absorbing specialised proteoid (cluster) roots of proteaceous plants. Subsequent precipitation of the iron is then pictured as occurring onto the oxide rinds of developing laterite after consumption of the organic components of the complexes by soil bacteria. The hypothesis is f irst examined in relation to current theories of origins of laterites and the extent of the coincidences worldwide in past and present times between Proteaceae and oligotrophic soil types of lateritic character. The paper then provides more definitive lines of evidence supporting the hypothesis, based largely on recent studies by the authors in south-western Western Australia. This relates to (a) cases of definitive association in habitats rich in Proteaceae between zones of root proliferation and ferricrete layers in lateritic soils, (b) proximity in soil profiles between ferric deposits and current and ancestral root channels, (c) the recovery of citrate-consuming bacteria from soil profiles and specifically from ferricrete rinds and horizons accumulating sesquioxide organic matter and (d) distribution of iron and phosphorus within plant and soil profile components consistent with ferricrete rinds being generated by rhizosphere-mediated interactions of plants and microbes under conditions of severely limited availability of phosphorus. The mode of functioning of proteoid root clusters is then discussed, especially in relation to exudation of organic acid anions, uptake of phosphorus and the subsequent fate of organic anions and their metal ion complexes in the system. An empirically based scheme is presented indicating flow profiles for phosphorus and iron between soil, ferricrete rinds and bacterial and plant components. We then discuss possible carbon costs to proteaceous plant partners when accessing phosphorus under the nutrient-impoverished conditions typical of heathlands and open woodlands of Mediterranean-type ecosystems of Western Australia. The paper concludes with a critical overview of the hypothesis, particularly its implications regarding possible higher plant: microbial influences shaping soil and landscape evolution in the regions involved.
41
Ross, Ian L., Younes Alami, Paul R. Harvey, Wafa Achouak e Maarten H. Ryder. "Genetic Diversity and Biological Control Activity of Novel Species of Closely Related Pseudomonads Isolated from Wheat Field Soils in South Australia". Applied and Environmental Microbiology 66, n. 4 (1 aprile 2000): 1609–16. http://dx.doi.org/10.1128/aem.66.4.1609-1616.2000.
Testo completoAbstract (sommario):
ABSTRACT Rhizobacteria closely related to two recently described species of pseudomonads, Pseudomonas brassicacearum andPseudomonas thivervalensis, were isolated from two geographically distinct wheat field soils in South Australia. Isolation was undertaken by either selective plating or immunotrapping utilizing a polyclonal antibody raised against P. brassicacearum. A subset of 42 isolates were characterized by amplified 16S ribosomal DNA restriction analysis (ARDRA), BIOLOG analysis, and gas chromatography-fatty acid methyl ester (GC-FAME) analysis and separated into closely related phenetic groups. More than 75% of isolates tested by ARDRA were found to have >95% similarity to either Pseudomonas corrugata or P. brassicacearum-P. thivervalensis type strains, and all isolates had >90% similarity to either type strain. BIOLOG and GC-FAME clustering showed a >70% match to ARDRA profiles. Strains representing different ARDRA groups were tested in two soil types for biological control activity against the soilborne plant pathogen Gaeumannomyces graminis var. tritici, the causative agent of take-all of wheat and barley. Three isolates out of 11 significantly reduced take-all-induced root lesions on wheat plants grown in a red-brown earth soil. Only one strain, K208, was consistent in reducing disease symptoms in both the acidic red-brown earth and a calcareous sandy loam. Results from this study indicate that P. brassicacearum and P. thivervalensis are present in Australian soils and that a level of genetic diversity exists within these two novel species but that this diversity does not appear to be related to geographic distribution. The result of the glasshouse pot trial suggests that some isolates of these species may have potential as biological control agents for plant disease.
42
Franco, CMM, ME Tate e JM Oades. "Studies on non-wetting sands .1. The role of intrinsic particulate organic-matter in the development of water-repellency in non-wetting sands". Soil Research 33, n. 2 (1995): 253. http://dx.doi.org/10.1071/sr9950253.
Testo completoAbstract (sommario):
The bulk of the organic matter in sands from the south-east of South Australia is present as discrete particles which constitute 4-6% of the mass of the sand. Hydrophobic particulate organic matter was separated from non-wetting sand obtained from two sites in the south-east of South Australia and characterized with respect to size and ability to induce water-repellency. When heated with both a wettable acid washed sand and a natural sand (non-wetting sand washed free of particulate organic matter), the intrinsic particulate organic matter induced strong water-repellence. The degree of hydrophobicity created was higher with the natural-washed sand than the acid-washed sand which indicated that a precoated surface, even one with a low initial hydrophobicity, has a strong enhancing effect. Particulate organic matter, especially the larger size fractions, acted as a reservoir of waxes or hydrophobic materials which diffused onto the surfaces of sand grains during heating, and particularly during wetting/heating/drying cycles. Thus, intrinsic particulate organic matter plays a substantial role in the development of water-repellency in sandy soils. In addition to hydrophobic waxes which diffuse out under environmental conditions prevalent in the field, water-repellency increases significantly when these hydrophobic particles interact with the natural precoated hydrophobic surface of the sand.
43
Culvenor, Richard A., Stuart Kemp e Kevin F. M. Reed. "Characterisation of Sardinian germplasm of the perennial pasture grass Phalaris aquatica". Crop and Pasture Science 71, n. 9 (2020): 850. http://dx.doi.org/10.1071/cp20216.
Testo completoAbstract (sommario):
Germplasm of the perennial pasture grass Phalaris aquatica L., from Sardinia, Italy, is a potentially valuable source for grass breeders owing to climatic similarities to regions where P. aquatica is used, a relatively high incidence of acidic soils, and exposure to prolonged grazing pressure. At field sites in south-eastern Australia, Sardinian accessions were compared as spaced plants and drill-rows with accessions from southern Europe and north-western Africa and with commercial cultivars. They were also evaluated in grazed swards at three sites over 4 years under conditions that challenge persistence, including heavy grazing pressure, acid soils and drought. Morphologically, the accessions were comparatively dense, fine and short, with similarities to southern European accessions and cultivars of the cv. Australian type. However, they were earlier heading and more summer-dormant, particularly those from southern Sardinia. In drill-rows, Sardinian accessions were later heading and less productive in winter than accessions from Morocco. In swards, Sardinian accessions had lower seedling vigour and winter growth potential than modern winter-active cultivars. However, they were dense and persistent under high grazing pressure, and some accessions survived better than all cultivars on an acid, low-fertility soil. Developing cultivars that are superior to the cv. Australian type with acceptable seed production and alkaloid levels presents a challenge to breeders. However Sardinian germplasm offers a range of maturity times combined with higher levels of summer dormancy and a grazing-tolerant morphology, attributes that may expand the area of adaptation of the species into the hotter and more drought-prone margin.
44
Rosicky, Mark A., Leigh A. Sullivan, Peter G. Slavich e Mike Hughes. "Soil properties in and around acid sulfate soil scalds in the coastal floodplains of New South Wales, Australia". Soil Research 42, n. 6 (2004): 595. http://dx.doi.org/10.1071/sr03078.
Testo completoAbstract (sommario):
Soil profiles in 10 persistently bare areas (i.e. scalds), mainly located in coastal backswamps of New South Wales, Australia, were examined for chromium-reducible sulfur content and selected chemical properties. At 5 of the sites, the adjacent paddocks with vegetation cover were also examined. All of the tested sites had been affected by the extensive drainage of the surrounding acid sulfate soil (ASS) landscapes and the consequent oxidation of pyrite. All sites had low pH values in the surface soil layers and these low pH values extended for up to 150 cm into the underlying unoxidised blue/grey pyritic estuarine gels. This can be attributed to the downward diffusion of acidity, either produced in the overlying oxidised zones of these soils or transported laterally across the landscape to these low-lying areas. Acidified unoxidised pyritic zones 120 cm thick can evidently form within several decades after drainage disturbance. At the scalded sites the depth from the soil surface to the main pyritic zone varied from the surface to >200 cm depth, indicating that this variable is not critical to ASS scald formation. For most of the sites examined, the chromium-reducible sulfur contents in the surface soil layers were appreciably higher than those in the immediately underlying soil layers. In most of the vegetated sites the chromium-reducible sulfur content in the surface layers was considerably higher than for the adjacent scalded site. The conditions necessary for pyrite formation (i.e. adequate supplies of organic matter, soluble iron, sulfate, and waterlogging) were found to exist at all sites, and the pyrite accumulations in these surface soil layers are considered to be neo-formed. The vegetated soil-profile pyrite and pH results were very similar to their scalded counterparts except that they had an extra 20–40 cm layer of vegetation and mulch that was missing from the scalded profiles. This indicates that there is considerable potential for more extensive scalding in these ASS areas.
45
CHEN, G., G. D. LI, M. K. CONYERS e B. R. CULLIS. "LONG-TERM LIMING REGIME INCREASES PRIME LAMB PRODUCTION ON ACID SOILS". Experimental Agriculture 45, n. 2 (aprile 2009): 221–34. http://dx.doi.org/10.1017/s0014479708007497.
Testo completoAbstract (sommario):
SUMMARYPrime lamb live weight response to lime application on pasture was measured in a grazing experiment in the high rainfall zone of the southwestern slopes of New South Wales, Australia. The pastures were limed every 6 years over 15 years. First cross South African Meat Merino lambs were used as test animals. Pre- and post-grazing pasture dry matter (DM) yield, botanical composition, feed quality and lamb live weight were monitored over 12 weeks in 2007. Results showed that liming significantly increased pasture DM yield of high quality species and improved overall pasture quality due to increased digestibility and metabolic energy content. As a result, the limed perennial and annual pastures carried 24.0% (3.6 lambs ha−1) and 29.0% (4.4 lambs ha−1) more stock than the unlimed perennial and annual pastures, respectively. Averaged across pasture types, the limed pastures produced 30.6% (131 kg ha−1) more lamb live weight gain than the unlimed pastures over 12 weeks. The live weight gain varied between grazing cycles depending on the availability of feed-on-offer and feed quality, which were closely related to the rainfall pattern. The perennial pastures did not show any advantage in animal production over annual pastures during the experimental period due to lack of moisture in the deep soil profile because of severe drought in the previous year. More seasons with normal or above average rainfall are needed to compare animal production on perennial pastures and annual pastures to investigate the advantage of perennial pastures in animal production.
46
Le, Thi Minh Hue, An Ninh Pham, Richard N. Collins e T. David Waite. "Impact of soil consolidation and solution composition on the hydraulic properties of coastal acid sulfate soils". Soil Research 46, n. 2 (2008): 112. http://dx.doi.org/10.1071/sr07119.
Testo completoAbstract (sommario):
Acid sulfate soils (ASS) are distributed worldwide on coastal floodplains, presenting a great challenge to coastal development and urbanisation. Upon oxidation, these soils become stratified with visibly distinguishable soil strata that are progressively less oxidised with depth. In this study, the geotechnical properties, quantified by hydraulic conductivity and consolidation coefficient, of an ASS profile from the Tweed River floodplain, north-eastern New South Wales, Australia, were investigated at a laboratory scale and compared with results obtained from the field. Measurements were conducted with a Rowe cell (or hydraulic consolidometer) by controlled compressive and pore water pressures. The results indicated that hydraulic conductivity and consolidation coefficient values gradually decreased with increasing consolidation pressure or decreasing void ratio, but were significantly higher for the more oxidised ASS horizons. These results suggest that controlled soil consolidation along ASS drainage banks may prove to be effective at reducing acid discharge. Passing low pH (pH 3) or high cation concentration (50 mm CaCl2) solutions through intact consolidated potential ASS samples did not induce changes in the hydraulic conductivity or consolidation coefficient of this material indicating that ASS soil ripening involves more than acidification reactions, and the practice of flushing drains with high ionic strength estuarine tidal waters is unlikely to induce soil subsidence as a result of ASS structural change and clay flocculation.
47
Baker, G. H., P. J. Carter e V. J. Barrett. "Survival and biomass of exotic earthworms, Aporrectodea spp. (Lumbricidae), when introduced to pastures in south-eastern Australia". Australian Journal of Agricultural Research 50, n. 7 (1999): 1233. http://dx.doi.org/10.1071/ar98181.
Testo completoAbstract (sommario):
The earthworm fauna of pastures in south-eastern Australia is dominated by exotic lumbricid earthworms, in particular the endogeic species, Aporrectodea caliginosa and A. trapezoides. Anecic species such as A. longa are very rare. All 3 species were introduced within cages in 10 pastures on a range of soil types within the region. Five months later, A. longa had generally survived the best and A. trapezoides the worst. The survivals and weights of individual worms varied between sites for all 3 species. The survivals of A. caliginosa and A. longa, and to a lesser extent A. trapezoides, were positively correlated with soil clay content. The weights of A. caliginosa and A. longa, but not A. trapezoides, were positively correlated with soil P content. The survivals and weights of A. longa and A. trapezoides and the weights only of A. caliginosa decreased with increasing inoculation density, suggesting increased intraspecific competition for resources, particularly in the first two species. A. longa reduced the abundance and biomass of the exotic acanthodrilid earthworm, Microscolex dubius, at one site, and the total biomass of 3 native megascolecid species at another, when these latter species occurred as contaminants in A. longa cages. The addition of lime had no effect on the survivals and weights of A. caliginosa, A. longa, and A. trapezoides, although the soils were acid at the sites tested. The addition of sheep dung increased the survival and weights of some species at some sites. Mechanical disturbance of the soil within cages reduced the survivals of A. longa and A. trapezoides. A. longa was released without being caged at 25 sites within one pasture in South Australia. Four years later, it was recovered at all release points. A. longa has the potential to colonise pastures widely throughout the higher rainfall regions of south-eastern Australia.
48
Amaral, Valter, Henrique N. Cabral e Melanie J. Bishop. "Effect of runoff from acid-sulfate soils on pneumatophores of the grey mangrove, Avicennia marina". Marine and Freshwater Research 62, n. 8 (2011): 974. http://dx.doi.org/10.1071/mf11003.
Testo completoAbstract (sommario):
Runoff from acid-sulfate soils (ASS) is increasingly threatening the structure and function of estuarine ecosystems worldwide. Along the eastern coast of Australia, sulfuric acid is known to affect the growth and survival of mangrove saplings; however, impacts of ASS runoff on the structure and function of established mangrove trees are unclear. Pneumatophores, the aerial roots produced by some species of mangrove, are critical sites of gas exchange, allowing these species to persist in waterlogged soils. They also provide physical structure in estuarine sediments, facilitating communities of algae, invertebrates and, at high tide, fish. We tested the hypotheses that Avicennia marina (Forsk.) Vierh. pneumatophores would be less abundant, shorter, thinner and weaker close to major ASS outflow drains. Sampling at sites close to and away from drains within each of two estuaries of New South Wales, Australia, showed no effect of exposure to runoff on pneumatophore density or thickness. Pneumatophores were, however, shorter (~2 cm) and weaker (up to two-fold) at ASS-affected than reference sites. Although the reduced length and strength of pneumatophores at acidified sites may limit the number of epifaunal molluscs they can support, the persistence of dense pneumatophores indicates that the capacity to benefit invertebrates and fish remains.
49
Ward, P. R. "Predicting the impact of perennial phases on average leakage from farming systems in south-western Australia". Australian Journal of Agricultural Research 57, n. 3 (2006): 269. http://dx.doi.org/10.1071/ar04137.
Testo completoAbstract (sommario):
Rising watertables and dryland salinity in southern Australia are due to excess groundwater recharge after the replacement of native vegetation by annual crops and pastures. The inclusion of perennial plants into agricultural systems has been proposed as a possible method of recharge reduction, through the creation of a buffer (extra water storage capacity generated by the perennial in comparison with an annual crop or pasture). However, the role of perennial phases under conditions of highly episodic leakage is not well understood. In this paper, a simple Leakage/Buffer Model (LeBuM) was developed to determine the effect of perennial phases on long-term average annual leakage, incorporating episodic events. Mechanistic modelling studies on contrasting soil types were used to demonstrate that leakage for any given May–December period was directly related to soil water storage at 1 May. From this finding, it follows that leakage from a phase rotation can be calculated if the size of the buffer, and the leakage quantity in the absence of a buffer, are known for each stage of the rotation. LeBuM uses a long-term sequence of leakage values in the absence of a buffer as input, and the maximum buffer size, its rate of development, and the length of perennial and annual phases are specified as parameters. LeBuM was applied to leakage data modelled for 5 contrasting soil types over 100 years at 24 sites in the Western Australian wheatbelt. Phase rotations on duplex, waterlogging duplex, or loamy sand soils reduced leakage by >90% for regions with <380 mm annual rainfall, but were less effective in wetter regions and on deep sands or acid loamy sands. Nevertheless, phase rotations if adopted widely could delay the onset of salinity by as much as several decades.
50
Rosicky, Mark A., Peter Slavich, Leigh A. Sullivan e Mike Hughes. "Surface and sub-surface salinity in and around acid sulfate soil scalds in the coastal floodplains of New South Wales, Australia". Soil Research 44, n. 1 (2006): 17. http://dx.doi.org/10.1071/sr05027.
Testo completoAbstract (sommario):
Two-metre-deep soil profiles at 10 acid sulfate soil (ASS) scalds along the coast of New South Wales (NSW), Australia, were examined for salinity indicators. At 5 of the sites, permanently vegetated areas adjacent to the ASS-scalded land were also tested. Throughout the profiles, most sites had high soluble chloride (Cl−) concentrations (≤17 mg/g soil) and high soluble sulfate (SO42−) concentrations (≤17 mg/g soil). Very low Cl− : SO42− ratios (≤3) indicated active pyrite oxidation. Soil salinity (measured as electrical conductivity, EC) was extremely high in the top 2 m of most of the ASS scalds when related to the growth requirements of the typical introduced pasture species that were planted in these areas following drainage. This allows salinity, in addition to the extremely low pH of the surface soils, to contribute to land denudation, which can instigate or perpetuate pyrite oxidation and ASS-related land scalding. Although the sites had shallow watertables and soil-moisture content was high, the surface soil (top 0.10 m) of the scalds had consistently higher soluble Cl− and SO42− concentrations and EC than adjacent vegetated areas. All coastal ASS areas investigated, typically freshwater backswamps used for cattle grazing, were underlain by estuarine-derived sediments containing saline ground water. The results demonstrate that revegetation of ASS scalds must include investigation and management of salinity, in addition to acidity, within the soil profile and at the soil surface.