Journal articles on the topic 'Soils and climate Australia'
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1
O'Sullivan, Cathryn A., Steven A. Wakelin, Ian R. P. Fillery, and Margaret M. Roper. "Factors affecting ammonia-oxidising microorganisms and potential nitrification rates in southern Australian agricultural soils." Soil Research 51, no. 3 (2013): 240. http://dx.doi.org/10.1071/sr13039.
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Ammonia-oxidising archaea (AOA) have recently been described as having an important role in soil nitrification. However, published data on factors which influence their distribution and their impact on a soil’s potential nitrification rates (PNR) are sparse, particularly compared with the amount of information available regarding ammonia-oxidising bacteria (AOB). This study had two aims. First, to investigate which environmental factors affect the AOA : AOB ratio in soils from two agricultural regions, and second, to explore whether the abundance of either AOA or AOB correlated with PNR. Samples were collected from 45 sites within the cropping regions of Western Australia and South Australia. Soils were tested for pH, NH4+/NO3–, organic carbon (C), total nitrogen (N), C : N ratio, PNR, and electrical conductivity. Climate data were obtained from the Queensland Climate Change Centre for Excellence SILO website. Abundances of AOA and AOB were measured using real-time PCR quantification of the gene encoding the ammonia monooxygenase enzyme (amoA). Multivariate statistical analysis was applied to assess correlations between PNR, soil properties, and abundance of AOA or AOB. In the majority samples AOA were present, but their abundance, and the AOA : AOB ratio, varied considerably between sites. Multivariate analysis showed that the distribution of AOA and AOB and the AOA : AOB ratio were strongly correlated with climatic and seasonal factors. Sites where samples were collected during dry, hot periods tended to be AOA-dominated, whereas samples collected during cool, wet periods tended to be AOB-dominated or have equal abundances of AOA and AOB. The PNRs were correlated with total N content, organic C content, and soil pH. There was no clear correlation between AOA or AOB and PNR. This study shows that both AOA and AOB are widespread in Western Australian and South Australian soils and their abundance and ratio are affected by climate and season. It also shows that PNR is more strongly influenced by soil fertility factors than by the AOA : AOB ratio.
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Simpson, Stuart L., Rob W. Fitzpatrick, Paul Shand, Brad M. Angel, David A. Spadaro, and Luke Mosley. "Climate-driven mobilisation of acid and metals from acid sulfate soils." Marine and Freshwater Research 61, no. 1 (2010): 129. http://dx.doi.org/10.1071/mf09066.
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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.
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Turner, NC. "Crop production on duplex soils: an introduction." Australian Journal of Experimental Agriculture 32, no. 7 (1992): 797. http://dx.doi.org/10.1071/ea9920797.
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Duplex or texture-contrast soils occur over about 60% of the agricultural areas of south-west Western Australia. Annual crops of wheat, barley, oats, and lupins predominate on these soils, grown in rotation with annual pastures. The climate is characterised by cool, wet winters and hot, dry summers. Crop production is restricted to the winter and spring and is limited by waterlogging in the wet winter months and by water shortage during grain filling in spring. Research on crop production on duplex soils has been undertaken for the past 8 years by a collaborative team from the CSIRO Dryland Crops andyoils Program and the Western Australian Department of Agriculture. This research has been focussed on 3 sites at which processes limiting crop production on duplex soils have been highlighted. This special issue was initiated to summarise that research and to put it in its regional and national perspective. Additionally, opportunity was taken to compare and contrast experiences both within Western Australia and throughout Australia, and to draw out management options for crop production on duplex soils.
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Barron, O. V., R. S. Crosbie, D. Pollock, W. R. Dawes, S. P. Charles, T. Pickett, and M. Donn. "Climatic controls on diffuse groundwater recharge across Australia." Hydrology and Earth System Sciences Discussions 9, no. 5 (May 9, 2012): 6023–62. http://dx.doi.org/10.5194/hessd-9-6023-2012.
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Abstract. Reviews of field studies of groundwater recharge have attempted to investigate how climate characteristics control recharge, but due to a lack of data have not been able to draw any strong conclusions beyond that rainfall is the major determinant. This study has used numerical modeling for a range of Köppen-Geiger climate types (tropical, arid and temperate) to investigate the effect of climate variables on recharge for different soil and vegetation types. For the majority of climate types the total annual rainfall had a weaker correlation with recharge than the rainfall parameters reflecting rainfall intensity. In regions with winter-dominated rainfall, annual recharge under the same annual rainfall, soils and vegetation conditions is greater than in regions with summer-dominated rainfall. The relative importance of climate parameters other than rainfall is higher for recharge under annual vegetation, but overall is highest in the tropical climate type. Solar radiation and vapour pressure deficit show a greater relative importance than mean annual daily mean temperature. Climate parameters have lowest relative importance in the arid climate type (with cold winters) and the temperate climate type. For 75% of all considered cases of soil, vegetation and climate types recharge elasticity varies between 2 and 4, indicating a 20% to 40% change in recharge for a 10% change in annual rainfall Understanding how climate controls recharge under the observed historical climate allows more informed choices of analogue sites if they are to be used for climate change impact assessments.
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Doolette, Ashlea L., Ronald J. Smernik, and Timothy I. McLaren. "The composition of organic phosphorus in soils of the Snowy Mountains region of south-eastern Australia." Soil Research 55, no. 1 (2017): 10. http://dx.doi.org/10.1071/sr16058.
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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.
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Naidu, R., and P. Rengasamy. "Ion interactions and constraints to plant nutrition in Australian sodic soils." Soil Research 31, no. 6 (1993): 801. http://dx.doi.org/10.1071/sr9930801.
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Many of the arable soils in Australia are affected by salinity and/or sodicity. Nutrient deficiency and ion toxicity may occur in both saline and sodic soils. Ho-ever, the mechanism for these constraints on plant growth in sodic soils differs from that of saline soils. Fertility of sodic soils with low nutrient reserves is compounded by the low supply of water and oxygen to roots in profiles with dispersive clays. Nutrient constraints in sodic soils are created by the electron and proton activities (pE and pH) in an environment of degraded soil structure. Australian sodic soils accumulate relatively low levels of organic matter. High sodium, high pH and low biological activity, commonly found in these soils, are not conducive for both the accumulation of organic matter and its mineralization. As a result, these soils are deficient in N and S. Australian soils are highly weathered and have moderate to low reserves of many plant nutrients such as Cu, Mn, Mo, Zn and P. Solubility of phosphorus is generally increased in sodic soils. Poor leaching conditions accumulate boron in soil layers. Higher concentrations of sodium than of calcium in these soils are the major cause of both physical and nutritional problems. Therefore, amelioration of sodicity is the logical first step in improving the chemical fertility of sodic soils. However, fertilizer application and improvement of soil organic matter are essential to increase yields to match the potential yield predictable from climate.
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Morris, Peter H., J. Graham, and David J. Williams. "Cracking in drying soils." Canadian Geotechnical Journal 29, no. 2 (April 1, 1992): 263–77. http://dx.doi.org/10.1139/t92-030.
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Cracking in soils that are undergoing drying is controlled by soil suctions and by soil properties such as compression modulus, Poisson's ratio, shear strength, tensile strength, and specific surface energy. The paper reviews the occurrence and morphology of cracks in dry-climate regions of Australia and Canada. After reviewing the behaviour of unsaturated soils and the mechanics of cracking, solutions are developed based on (i) elasticity theory, (ii) the transition between tensile and shear failure, and (iii) linear elastic fracture mechanics. The solutions are compared and related to crack depths observed in the field. Key words : clay, cracks, crust, shear strength, soil suction, tensile strength, unsaturated soil, weathering.
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Karim, Md Rajibul, Md Mizanur Rahman, Khoi Nguyen, Donald Cameron, Asif Iqbal, and Isaac Ahenkorah. "Changes in Thornthwaite Moisture Index and Reactive Soil Movements under Current and Future Climate Scenarios—A Case Study." Energies 14, no. 20 (October 17, 2021): 6760. http://dx.doi.org/10.3390/en14206760.
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Expansive soils go through significant volume changes due to seasonal moisture variations resulting in ground movements. The ground movement related problems are likely to worsen in the future due to climate change. It is important to understand and incorporate likely future changes in design to ensure the resilience of structures built on such soils. However, there has been a limited amount of work quantifying the effect of climate change on expansive soils movement and related behaviour of structures. The Thornthwaite Moisture Index (TMI) is one of the commonly used climate classifiers in quantifying the effect of atmospheric boundary on soil behaviour. Using the long-term weather data and predicted future changes under different emission scenarios, a series of TMI maps are developed for South Australia. Potential changes in ground movement are then estimated for a selected area using a simplified methodology where the effect of future climate is captured through changes in TMI. Results indicate that South Australia is likely to face a significant reduction in TMI under all emission scenarios considered in this study. The changes in TMI will lead to a considerable increase in potential ground movement which will influence the behaviour of structures built on them and in some areas may lead to premature failure if not considered in the design.
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Pound, M. J., J. Tindall, S. J. Pickering, A. M. Haywood, H. J. Dowsett, and U. Salzmann. "Late Pliocene lakes and soils: a global data set for the analysis of climate feedbacks in a warmer world." Climate of the Past 10, no. 1 (January 23, 2014): 167–80. http://dx.doi.org/10.5194/cp-10-167-2014.
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Abstract. The global distribution of late Pliocene soils and lakes has been reconstructed using a synthesis of geological data. These reconstructions are then used as boundary conditions for the Hadley Centre General Circulation Model (HadCM3) and the BIOME4 mechanistic vegetation model. By combining our novel soil and lake reconstructions with a fully coupled climate model we are able to explore the feedbacks of soils and lakes on the climate of the late Pliocene. Our experiments reveal regionally confined changes of local climate and vegetation in response to the new boundary conditions. The addition of late Pliocene soils has the largest influence on surface air temperatures, with notable increases in Australia, the southern part of northern Africa and in Asia. The inclusion of late Pliocene lakes increases precipitation in central Africa and at the locations of lakes in the Northern Hemisphere. When combined, the feedbacks on climate from late Pliocene lakes and soils improve the data to model fit in western North America and the southern part of northern Africa.
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Pound, M. J., J. Tindall, S. J. Pickering, A. M. Haywood, H. J. Dowsett, and U. Salzmann. "Late Pliocene lakes and soils: a data – model comparison for the analysis of climate feedbacks in a warmer world." Climate of the Past Discussions 9, no. 3 (June 17, 2013): 3175–207. http://dx.doi.org/10.5194/cpd-9-3175-2013.
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Abstract. Based on a synthesis of geological data we have reconstructed the global distribution of Late Pliocene soils and lakes which are then used as boundary conditions in a series of model experiments using the Hadley Centre General Circulation Model (HadCM3) and the BIOME4 mechanistic vegetation model. By combining our novel soil and lake reconstructions with a fully coupled climate model we are able to explore the feedbacks of soils and lakes on the climate of the Late Pliocene. Our experiments reveal regionally confined changes of local climate and vegetation in response to the new boundary conditions. The addition of Late Pliocene soils has the largest influence on surface air temperatures, with notable increases in Australia, southern North Africa and Asia. The inclusion of Late Pliocene lakes generates a significant increase in precipitation in central Africa, as well as seasonal increases in the Northern Hemisphere. When combined, the feedbacks on climate from Late Pliocene lakes and soils improve the data to model fit in western North America and southern North Africa.
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Rengasamy, P., and KA Olsson. "Irrigation and sodicity." Soil Research 31, no. 6 (1993): 821. http://dx.doi.org/10.1071/sr9930821.
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The productivity of irrigated agriculture in Australia is low for most crops and one important factor is the physical and chemical constraints caused by sodicity in the rootzone. Over 80% of the irrigated soils are sodic and have degraded structure limiting water and gas transport and root growth. Irrigation, without appropriate drainage, leads to the buildup of salts in soil solutions with increased sodium adsorption ratio (SAR) and can develop perched watertables due to a very low leaching fraction of the soil layers exacerbated by sodicity. Therefore, irrigation management in Australia is closely linked with the management of soil sodicity.The inevitable consequence of continued irrigation of crops and pastures with saline-sodic water without careful management is the further sodification of soil layers and concentration of salt in the rootzone. This will increase the possibility of dissolving toxic elements from soil minerals. The yields of crops can be far below the potential yields determined by climate. The cost of continued use of amendments and fertilizers to maintain normal yields will increase under saline-sodic irrigation. Most of the irrigated soils in Australia need reclamation of sodicity of soil layers at least in the rootzone. The management of these sodic soils involves the application of gypsum, suitable tillage and the maintenance of structure by the buildup of organic matter and biological activity aver time. Then artificial drainage, an essential component of the management of irrigated sodic soils, is possible. By following these soil management practices, irrigated agriculture in Australia will become sustainable with increased yields and high economic returns.
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Baldock, J. A., I. Wheeler, N. McKenzie, and A. McBrateny. "Soils and climate change: potential impacts on carbon stocks and greenhouse gas emissions, and future research for Australian agriculture." Crop and Pasture Science 63, no. 3 (2012): 269. http://dx.doi.org/10.1071/cp11170.
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Organic carbon and nitrogen found in soils are subject to a range of biological processes capable of generating or consuming greenhouse gases (CO2, N2O and CH4). In response to the strong impact that agricultural management can have on the amount of organic carbon and nitrogen stored in soil and their rates of biological cycling, soils have the potential to reduce or enhance concentrations of greenhouse gases in the atmosphere. Concern also exists over the potential positive feedback that a changing climate may have on rates of greenhouse gas emission from soil. Climate projections for most of the agricultural regions of Australia suggest a warmer and drier future with greater extremes relative to current climate. Since emissions of greenhouse gases from soil derive from biological processes that are sensitive to soil temperature and water content, climate change may impact significantly on future emissions. In this paper, the potential effects of climate change and options for adaptation and mitigations will be considered, followed by an assessment of future research requirements. The paper concludes by suggesting that the diversity of climate, soil types, and agricultural practices in place across Australia will make it difficult to define generic scenarios for greenhouse gas emissions. Development of a robust modelling capability will be required to construct regional and national emission assessments and to define the potential outcomes of on-farm management decisions and policy decisions. This model development will require comprehensive field datasets to calibrate the models and validate model outputs. Additionally, improved spatial layers of model input variables collected on a regular basis will be required to optimise accounting at regional to national scales.
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Finn, Damien, Ram Dalal, and Athol Klieve. "Methane in Australian agriculture: current emissions, sources and sinks, and potential mitigation strategies." Crop and Pasture Science 66, no. 1 (2015): 1. http://dx.doi.org/10.1071/cp14116.
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Methane is a potent greenhouse gas with a global warming potential ~28 times that of carbon dioxide. Consequently, sources and sinks that influence the concentration of methane in the atmosphere are of great interest. In Australia, agriculture is the primary source of anthropogenic methane emissions (60.4% of national emissions, or 3 260 kt–1 methane year–1, between 1990 and 2011), and cropping and grazing soils represent Australia’s largest potential terrestrial methane sink. As of 2011, the expansion of agricultural soils, which are ~70% less efficient at consuming methane than undisturbed soils, to 59% of Australia’s land mass (456 Mha) and increasing livestock densities in northern Australia suggest negative implications for national methane flux. Plant biomass burning does not appear to have long-term negative effects on methane flux unless soils are converted for agricultural purposes. Rice cultivation contributes marginally to national methane emissions and this fluctuates depending on water availability. Significant available research into biological, geochemical and agronomic factors has been pertinent for developing effective methane mitigation strategies. We discuss methane-flux feedback mechanisms in relation to climate change drivers such as temperature, atmospheric carbon dioxide and methane concentrations, precipitation and extreme weather events. Future research should focus on quantifying the role of Australian cropping and grazing soils as methane sinks in the national methane budget, linking biodiversity and activity of methane-cycling microbes to environmental factors, and quantifying how a combination of climate change drivers will affect total methane flux in these systems.
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Tiller, KG. "Urban soil contamination in Australia." Soil Research 30, no. 6 (1992): 937. http://dx.doi.org/10.1071/sr9920937.
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The current knowledge of the pollution of Australian urban soils was reviewed with special reference to heavy metals. Increased community concern in recent years has resulted m a major upsurge in the investigation and rehabilitation of contaminated soils. This has led to a concomitant reassessment and development of regulatory procedures, and the establishment of some new environmental agencies. This review considers sources and extent of contamination, and approaches to the establishment of reference background levels in urban and rural areas. Assessment of contaminated sites has been largely based on overseas experience but site specific approaches relevant to Australian soils and climates are needed and are being developed by State authorities in collaboration with the Australian and New Zealand Environmental and Conservation Council and the National Health and Medical Research Council. The need for soil-based research and for standardized soil sampling procedures for site evaluation and action is stressed. Many opportunities exist for soil scientists in solving problems of soil contamination and rehabilitation.
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Halliday, James. "Climate and soil in Australia." Journal of Wine Research 4, no. 1 (January 1993): 19–34. http://dx.doi.org/10.1080/09571269308717945.
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Culvenor, R. A., and R. J. Simpson. "Persistence traits in perennial pasture grasses: the case of phalaris (Phalaris aquatica L.)." Crop and Pasture Science 65, no. 11 (2014): 1165. http://dx.doi.org/10.1071/cp13333.
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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.
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Baker, G. H., P. J. Carter, and V. J. Barrett. "Influence of earthworms, Aporrectodea spp. (Lumbricidae), on lime burial in pasture soils in south-eastern Australia." Soil Research 37, no. 5 (1999): 831. http://dx.doi.org/10.1071/sr98106.
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The relative abilities of 3 exotic lumbricid earthworms, the endogeic Aporrectodea caliginosa and A. trapezoides and the anecic A. longa, to bury surface-applied lime and help ameliorate soil acidity were measured in cages in 7 pasture soils in south-eastern Australia. All 3 species buried lime, mostly within the top 5 cm of the soil profile, but A. longa buried it deeper than A. caliginosa and A. trapezoides. A. longa significantly increased soil pH at 15–20 cm depth at some sites within 5 months (winter–spring, the earthworm ‘season’ in the Mediterranean climate of south-eastern Australia). Lime burial varied markedly between sites. These site differences were explained, at least in part, by variations in rainfall. Lime burial increased with earthworm density. A minimum density of 214 A. longa/m 2 was needed to significantly enhance lime burial within one season. Higher densities were required for the other two species. However, per unit of biomass, A. caliginosa and A. trapezoides were generally more able to bury lime in the upper soil layers (2 . 5–10 cm depth) than A. longa. Agricultural soils in south-eastern Australia are dominated by shallow burrowing species such as A. caliginosa and A. trapezoides. Deeper burrowers such as A. longa are rare. Introduction of A. longa to soils in high-rainfall regions of south-eastern Australia, where it does not presently occur, should enhance lime burial and help reduce soil acidity.
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Lee, Juhwan, Raphael A. Viscarra Rossel, Mingxi Zhang, Zhongkui Luo, and Ying-Ping Wang. "Assessing the response of soil carbon in Australia to changing inputs and climate using a consistent modelling framework." Biogeosciences 18, no. 18 (September 22, 2021): 5185–202. http://dx.doi.org/10.5194/bg-18-5185-2021.
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Abstract. Land use and management practices affect the response of soil organic carbon (C) to global change. Process-based models of soil C are useful tools to simulate C dynamics, but it is important to bridge any disconnect that exists between the data used to inform the models and the processes that they depict. To minimise that disconnect, we developed a consistent modelling framework that integrates new spatially explicit soil measurements and data with the Rothamsted carbon model (Roth C) and simulates the response of soil organic C to future climate change across Australia. We compiled publicly available continental-scale datasets and pre-processed, standardised and configured them to the required spatial and temporal resolutions. We then calibrated Roth C and ran simulations to estimate the baseline soil organic C stocks and composition in the 0–0.3 m layer at 4043 sites in cropping, modified grazing, native grazing and natural environments across Australia. We used data on the C fractions, the particulate, mineral-associated and resistant organic C (POC, MAOC and ROC, respectively) to represent the three main C pools in the Roth C model's structure. The model explained 97 %–98 % of the variation in measured total organic C in soils under cropping and grazing and 65 % in soils under natural environments. We optimised the model at each site and experimented with different amounts of C inputs to simulate the potential for C accumulation under constant climate in a 100-year simulation. With an annual increase of 1 Mg C ha−1 in C inputs, the model simulated a potential soil C increase of 13.58 (interquartile range 12.19–15.80), 14.21 (12.38–16.03) and 15.57 (12.07–17.82) Mg C ha−1 under cropping, modified grazing and native grazing and 3.52 (3.15–4.09) Mg C ha−1 under natural environments. With projected future changes in climate (+1.5, 2 and 5.0 ∘C) over 100 years, the simulations showed that soils under natural environments lost the most C, between 3.1 and 4.5 Mg C ha−1, while soils under native grazing lost the least, between 0.4 and 0.7 Mg C ha−1. Soil under cropping lost between 1 and 2.7 Mg C ha−1, while those under modified grazing showed a slight increase with temperature increases of 1.5 ∘C, but with further increases of 2 and 5 ∘C the median loss of TOC was 0.28 and 3.4 Mg C ha−1, respectively. For the different land uses, the changes in the C fractions varied with changes in climate. An empirical assessment of the controls on the C change showed that climate, pH, total N, the C : N ratio and cropping were the most important controls on POC change. Clay content and climate were dominant controls on MAOC change. Consistent and explicit soil organic C simulations improve confidence in the model's estimations, facilitating the development of sustainable soil management under global change.
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Rengasamy, P. "Transient salinity and subsoil constraints to dryland farming in Australian sodic soils: an overview." Australian Journal of Experimental Agriculture 42, no. 3 (2002): 351. http://dx.doi.org/10.1071/ea01111.
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More than 60% of the 20 million ha of cropping soils in Australia are sodic and farming practices on these soils are mainly performed under dryland conditions. More than 80% of sodic soils in Australia have dense clay subsoils with high sodicity and alkaline pH (>8.5). The actual yield of grains in sodic soils is often less than half of the potential yield expected on the basis of climate, because of subsoil limitations such as salinity, sodicity, alkalinity, nutrient deficiencies and toxicities due to boron, carbonate and aluminate. Sodic subsoils also have very low organic matter and biological activity. Poor water transmission properties of sodic subsoils, low rainfall in dryland areas, transpiration by vegetation and high evaporation during summer have caused accumulation of salts in the root zone layers. This transient salinity, not influenced by groundwater, is extensive in many sodic soil landscapes in Australia where the watertable is deep. ‘Dryland salinity’ is currently given wide attention in the public debate and in government policies, but only focusing on salinity induced by shallow watertables. While 16% of the dryland cropping area is likely to be affected by watertable-induced salinity, 67% of the area has a potential for transient salinity not associated with groundwater and other subsoil constraints and costing the Australian farming economy in the vicinity of A$1330 million per year. A different strategy for different types of dryland salinity is essential for the sustainable management and improved productivity of dryland farming. This paper discusses the sodic subsoil constraints, different types of salinity in the dryland regions, the issues related to the management of sodic subsoils and the future priorities needed in addressing these problems. It also emphasises that transient salinity in the root zone of dryland agricultural soils is an important issue with potential for worse problems than watertable-induced seepage salinity.
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Moata, Melinda R. S., Ashlea L. Doolette, Ronald J. Smernik, Ann M. McNeill, and Lynne M. Macdonald. "Organic phosphorus speciation in Australian Red Chromosols: stoichiometric control." Soil Research 54, no. 1 (2016): 11. http://dx.doi.org/10.1071/sr15085.
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Organic phosphorus (P) plays an important role in the soil P cycle. It is present in various chemical forms, the relative amounts of which vary among soils, due to factors including climate, land use, and soil type. Few studies have investigated co-variation between P types or stoichiometric correlation with the key elemental components of organic matter– carbon (C) and nitrogen (N), both of which may influence P pool structure and dynamics in agricultural soils. In this study we determined the organic P speciation of twenty Australian Red Chromosols soils, a soil type widely used for cropping in Australia. Eight different chemical forms of P were quantified by 31P NMR spectroscopy, with a large majority (>90%) in all soils identified as orthophosphate and humic P. The strongest correlations (r2 = 0.77–0.85, P < 0.001) between P types were found among minor components: (i) between two inositol hexakisphosphate isomers (myo and scyllo) and (ii) between phospholipids and RNA (both detected as their alkaline hydrolysis products). Total soil C and N were correlated with phospholipid and RNA P, but not the most abundant P forms of orthophosphate and humic P. This suggests an influence of organic matter content on the organic P pool consisting of phospholipid and RNA, but not on inositol P or the largest organic P pool in these soils – humic P.
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Oliver, Y. M., and M. J. Robertson. "Quantifying the benefits of accounting for yield potential in spatially and seasonally responsive nutrient management in a Mediterranean climate." Soil Research 47, no. 1 (2009): 114. http://dx.doi.org/10.1071/sr08099.
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Crop yield potential is a chief determinant of nutrient requirements, but there is little objective information available on the gains in profitability that can be made by accounting for the influences of soil type and season on yield potential when making fertiliser decisions. We conducted such an assessment using crop growth simulation coupled to nutrient response curves for wheat-growing at 4 locations in the low-medium rainfall zone of Western Australia. At each location, the yield potential was simulated on 10 soil types with plant-available water capacity (PAWC) ranging from 34 to 134 mm, which represent the major soils types in Western Australia. Soil survey maps were available to quantify soil type variability and the historical climate record (1974–2005) for seasonal variability. The benefits possible for fertiliser (NPK) management that takes account of variation in crop yield potential due to season and soil type by having ‘perfect knowledge’ ranged from $2 to 40/ha. Seasonal variation was more important than soil type for the better soils (high PAWC), providing two-thirds of the benefit of perfect knowledge. On low PAWC soils, knowledge of soils and seasonal influences on yield potential were similar contributors to profit gains. An assessment of one yield forecasting system showed that about 50% of the maximum gains could be captured if seasons could be categorised as below, at, or above average at the time the fertiliser decision is made. In each catchment, 30–40% of fields showed scope for benefits in accounting for within-field variation in soil type due to large variation in PAWC, and therefore yield. Maximum profit gains and reductions in nutrient excess were greater in the low rainfall locations and also on the low PAWC soil types.
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Huth, Neil I., Michael J. Robertson, and Perry L. Poulton. "Regional differences in tree - crop competition due to soil, climate and management." Crop and Pasture Science 61, no. 9 (2010): 763. http://dx.doi.org/10.1071/cp09254.
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Large areas of trees are being planted in Australian agricultural lands for a range of environmental, ecological and economic reasons. In the medium to low rainfall zones, these plantings can negatively impact upon adjacent agricultural production through competition for soil moisture. The nature of the tree–crop competition zone and the means of managing it have been studied in the main southern cropping zones. However, the differences in soil, climate and agronomic systems in Australia’s northern dryland cropping zones could lead to differences in the competition processes and the management options needed to minimise them. In this study, the competition for soil moisture and resultant impacts on crop production were studied for a Eucalyptus argophloia windbreak on a farm near Warra, Queensland (26.93°S, 150.93°E). The results indicate well defined inner and outer competition zones, the extents of which agree with those found elsewhere in Australia and overseas. However, while the extent of the competition is comparable with other regions, local agronomic practices developed for variable climatic conditions and deep clay soils allow trees to extract soil water stored during fallow periods resulting in relatively higher production losses.
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Lewis, D. C., M. D. A. Bolland, R. J. Gilkes, and L. J. Hamilton. "Review of Australian phosphate rock research." Australian Journal of Experimental Agriculture 37, no. 8 (1997): 845. http://dx.doi.org/10.1071/ea96103.
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Summary. Most of the research on the effectiveness of phosphorus (P) fertilisers in Australia has involved comparing phosphate rock (PR) or partially acidulated PR (PAPR) with superphosphate (SP) or other water-soluble P fertilisers. There are many estimates of effectiveness (current relative effectiveness or CRE) which compared freshly-applied (current) PR and freshly-applied (current) SP. The CRE values for PR range from <0.1 to 2.5, with a mean value for apatite PR of 0.26 and 0.43 for calcined calcium iron aluminium PR (Calciphos). As measured in field experiments in the years after application, and using current SP as a basis for comparison, the residual effectiveness of PR (residual value or RV) is low and constant for up to 11 years after application. Phosphate rock is 5–30% as effective as current SP. The average value of RV for SP declines by about 40% in the first year after application, followed by a further 15% in the second year, and a further 30% over the remaining 6 years. Values of relative effectiveness and RV, and the rate of decline in RV differ substantially between sites and sometimes between plant species. Laboratory studies of reactions between PR and soil have shown that the poor effectiveness of PR is primarily due to the limited extent and rate of dissolution of these fertilisers compared with the almost complete and rapid dissolution of water-soluble P fertilisers. Many Australian soils are only moderately acid (pH in water >5.5) with low pH buffering capacities and they cannot quickly contribute a large supply of hydrogen ions to promote rapid dissolution of PR. Soils are commonly sandy and have low water-holding capacities; in the strongly seasonal Mediterranean climate of south-western and southern Australia, the fertilised surface soil rapidly dries between rains thereby restricting PR dissolution. This restricted dissolution contributes to the poor agronomic effectiveness of PR fertilisers. Studies in Western Australia have shown that the effectiveness of current and residual PR relative to current SP generally decreases with increasing level of application. Therefore, relative to current SP, PR fertilisers become less effective per unit of PR as more is applied to the soil. Consequently, PR fertilisers frequently cannot support the same maximum yield as current SP. Published work indicates that PR fertilisers cannot be regarded as economic substitutes for SP for most agricultural applications in Australia. However, much Australian research has used low reactive PRs in conditions that are not likely to favour even highly reactive PRs. The soils dry out between rains during the growing season and have insufficient hydrogen ions to cause rapid, extensive dissolution of even reactive PR. Research elsewhere has suggested that reactive apatite PRs can be as effective as SP for suitable soils and environments. These are soils that remain wet for the whole growing season and which contain sufficient hydrogen ions to cause rapid dissolution of reactive PR. Laboratory studies, in which there is no P leaching, on 254 different soils collected from throughout south-western Australia showed that 29 soils, all collected from >800 mm average annual rainfall areas, dissolved >40% highly reactive North Carolina PR, suggesting that in the field these soils could be suitable for highly reactive PRs. Insufficient research has been conducted in the high rainfall areas of Australia, where the environment is more likely to favour highly reactive PR, and PAPR made from highly reactive PR. Therefore, a national program was undertaken in 6 Australian states to identify circumstances under which PRs, including reactive PR and PAPR made from reactive PR, may be economic fertilisers for acidic soils in the high rainfall areas of Australia where agricultural production is largely based on pasture production.
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Shaygan, Mandana, and Thomas Baumgartl. "Simulation of the Effect of Climate Variability on Reclamation Success of Brine-Affected Soil in Semi-Arid Environments." Sustainability 12, no. 1 (January 2, 2020): 371. http://dx.doi.org/10.3390/su12010371.
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Soils in arid and semi-arid environments are threatened by salinization. A cost-effective and efficient way to reclaim saline land is through leaching. This will be most effective in situations where direct human impact is the cause for salinity, e.g., in environments affected by industrial use or land rehabilitation following mining. Irrigation, which is the most common means of achieving salt leaching, is not feasible for the reclamation of mine sites’ salt-affected soils located in remote areas, and thus, land reclamation largely relies on natural climatic conditions. This study was conducted to assess the effect of different climatic conditions of semi-arid environments on spatio-temporal salt leaching from brine-affected soil, and investigate the efficacy of the reduction of soil bulk density as a reclamation technique for saline land experiencing water scarcity. Three regions (represented by the Australian cities of Roma, Mount Isa, and Quilpie) representing semi-arid environments of Australia were selected, and their climatic scenarios (23 years) were applied to a validated HYDRUS-1D model. A brine-affected soil typical to Queensland, Australia, was chosen for this study. The investigations established that a greater number of individual high rainfall events resulted in a greater reduction of salinity in Roma (96%) and Mount Isa (93.31%) compared with Quilpie (58.75%), in which the soil salinity approached a level (<2 dS m−1) that was suitable for sustaining plant growth. Soil salinity reduced to 8 dS m−1 under the climatic conditions of the Quilpie region. This study also demonstrated that the success of salt leaching from a brine-affected soil is a consequence of a sensitive response to the depth of individual rainfall events rather than rainfall distribution and the total amount of rainfall, and is controlled by the physical properties of the soil. Where climatic conditions cannot solely assist with salt leaching, reclamation may be successful by reducing soil bulk density.
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Farré, Imma, Michael Robertson, and Senthold Asseng. "Reliability of canola production in different rainfall zones of Western Australia." Australian Journal of Agricultural Research 58, no. 4 (2007): 326. http://dx.doi.org/10.1071/ar06176.
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The area of canola in the wheat-based farming systems of the wheatbelt of Western Australia (WA) expanded rapidly during the 1990s and has subsequently decreased. Due to the short history of canola production in WA, there is little information on yield and oil content expectations in relation to rainfall, location, and soil type. In this paper we: (1) present the recent history of canola production in the context of the long-term climate record; (2) assess the effect of location, rainfall, soil type, and soil water at sowing on yield and oil content; and (3) determine cut-off sowing dates for profitable canola production. Simulations were run using the APSIM-Canola model with long-term climate records for 3 selected locations from the low-, medium-, and high-rainfall zones and different soil types. Analysis of recent trends in canola area showed that poor seasons and price volatility in the last few years have contributed to farmers’ perception of risk and hence the decline in area sown. Long-term simulations showed the importance of location, sowing date, soil type, and stored soil water at sowing on grain yield. Yield was negatively related to sowing date. Light-textured soils had lower yields and larger yield penalties with delayed sowing than heavy-textured soils. Soil water at sowing gave a yield advantage in most years in all locations studied, but especially in low- and medium-rainfall locations. Variation in oil content was most strongly affected by sowing date and location, while soil type and soil water at sowing had a minor effect. Long-term simulation analysis can be used as a tool to establish the latest possible sowing date to achieve profitable canola for different locations and soil types, given different canola prices and growing costs. Given the vulnerability of profitability to seasonal conditions, in the low- and medium-rainfall zone, the decision to grow canola should be tactical depending on stored soil water, sowing opportunities, seasonal climate outlook, prices, and costs. In contrast, in the high-rainfall zone, canola production is relatively low risk, and could become a reliable component of rotations.
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Asseng, S., F. X. Dunin, I. R. P. Fillery, D. Tennant, and B. A. Keating. "Potential deep drainage under wheat crops in a Mediterranean climate. II. Management opportunities to control drainage." Australian Journal of Agricultural Research 52, no. 1 (2001): 57. http://dx.doi.org/10.1071/ar99187.
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High rates of deep drainage in Western Australia are contributing to groundwater recharge and secondary salinity. Strategies are being sought to increase water use in cropping systems and to reduce deep drainage. Quantifying potential drainage through measurements is hampered by the high degree of complexity of these systems as a result of diverse soil types, a range of crops, and in particular the inherent seasonal variability. Simulation models can provide the appropriate means to extrapolate across time and space. The Agricultural Production Systems Simulator (APSIM) was used to explore the effect of alternative agronomic practices on wheat production and deep drainage for representative soils and rainfall regions of the central wheatbelt of Western Australia. Soil water profiles were reset each year to the lower limit of plant-available water, assuming maximum water use in the previous crop. The long-term simulation studies showed that management practices with N fertiliser directed at yield increase were most effective in achieving these aims in the medium to high rainfall regions. The corresponding effect for drainage reduction was marginal. The small effect on drainage control associated with production increase can be traced to the effect of rainfall distribution with major occurrences of both rainfall and drainage during winter (June–August) coinciding with the lowest potential atmospheric demand for evapotranspiration, in combination with low water-holding capacity soils. Nitrogen-induced increases in crop transpiration were in conjunction with reduced soil evaporation, which increased water use efficiency and occurred mostly after the main drainage period, but had little effect on deep drainage within the season. Similar outcomes of enhanced productivity with minor impact on deep drainage were noted with crops sown at different times and with a hypothetical wheat crop having a deeper rooting system. Simulations without resetting soil water each year enabled the quantification of potential carryover effects on long-term average deep drainage. The carry-over of soil water left behind at crop harvest reduced the water storage capacity of the soil in a subsequent year and could increase long-term deep drainage substantially, depending on soil type. Improved management increased late water use in the high rainfall region, in particular on better water-holding soils, and could largely reduce this carry-over effect. The current wheat-based cropping systems, even with alternative management practices, continue to be a major threat to sustainability on the low water-holding soils in the wheatbelt of Western Australia, as a main cause of secondary salinity.
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Page, K. L., R. C. Dalal, M. J. Pringle, M. Bell, Y. P. Dang, B. Radford, and K. Bailey. "Organic carbon stocks in cropping soils of Queensland, Australia, as affected by tillage management, climate, and soil characteristics." Soil Research 51, no. 8 (2013): 596. http://dx.doi.org/10.1071/sr12225.
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Research both nationally and internationally has indicated that no-till (NT) management used in combination with stubble retention has the potential to increase soil organic carbon (SOC) stocks in cropping soils relative to conventional tillage (CT). However, rates of SOC increase can vary depending on cropping system, climate, and soil type, making the quantification of carbon change difficult on a regional level. Various long-term trials and commercial sites throughout Queensland were used to compare rates of SOC change under CT and NT management in cropping soils, and to determine how climate and soil type interact to influence rates of change. It was observed that NT management was not capable of increasing SOC stocks under the crop–fallow rotation systems practised throughout Queensland, and was unlikely even to hold SOC stocks steady under current management practices. However, SOC losses under NT systems did appear to be slower than under CT, indicating that NT may slow SOC loss following a period of organic carbon input, for example, from a pasture ley. On a regional scale, biomass production (estimated through remote sensing), climate (specifically the vapour pressure deficit), and soil sand content could be used to adequately predict SOC stocks on commercial sites, indicating the importance of considering these factors when assessing SOC stocks following management change across the region.
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Ahmad, Waqar, Balwant Singh, Ram C. Dalal, and Feike A. Dijkstra. "Carbon dynamics from carbonate dissolution in Australian agricultural soils." Soil Research 53, no. 2 (2015): 144. http://dx.doi.org/10.1071/sr14060.
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Land-use and management practices on limed acidic and carbonate-bearing soils can fundamentally alter carbon (C) dynamics, creating an important feedback to atmospheric carbon dioxide (CO2) concentrations. Transformation of carbonates in such soils and its implication for C sequestration with climate change are largely unknown and there is much speculation about inorganic C sequestration via bicarbonates. Soil carbonate equilibrium is complicated, and all reactants and reaction products need to be accounted for fully to assess whether specific processes lead to a net removal of atmospheric CO2. Data are scarce on the estimates of CaCO3 stocks and the effect of land-use management practices on these stocks, and there is a lack of understanding on the fate of CO2 released from carbonates. We estimated carbonate stocks from four major soil types in Australia (Calcarosols, Vertosols, Kandosols and Chromosols). In >200-mm rainfall zone, which is important for Australian agriculture, the CaCO3-C stocks ranged from 60.7 to 2542 Mt at 0–0.3 m depth (dissolution zone), and from 260 to 15 660 Mt at 0–1.0 m depth. The combined CaCO3-C stocks in Vertosols, Kandosols and Chromosols were about 30% of those in Calcarosols. Total average CaCO3-C stocks in the dissolution zone represented 11–23% of the stocks present at 0–1.0 m depth, across the four soil types. These estimates provide a realistic picture of the current variation of CaCO3-C stocks in Australia while offering a baseline to estimate potential CO2 emission–sequestration through land-use changes for these soil types. In addition, we provide an overview of the uncertainties in accounting for CO2 emission from soil carbonate dissolution and major inorganic C transformations in soils as affected by land-use change and management practices, including liming of acidic soils and its secondary effects on the mobility of dissolved organic C. We also consider impacts of liming on mineralisation of the native soil C, and when these transformations should be considered a net atmospheric CO2 source or sink.
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Schoknecht, Noel. "Report card on sustainable natural-resource use in the agricultural regions of Western Australia." Soil Research 53, no. 6 (2015): 695. http://dx.doi.org/10.1071/sr14267.
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A ‘Report Card’, which summarises the current knowledge of the status and trend in land condition in the agricultural areas of the south-west of Western Australia, was published in 2013 by the Department of Agriculture and Food, Western Australia. The Report Card draws on best available evidence from government and industry on the current condition and trend of 10 soil- and water-related natural resource themes relevant to agriculture, and discusses the implications of these results for the agricultural industries. The report also discusses the three main factors driving the performance of the land, namely climate, land characteristics and land management. The first two factors are largely out of the control of land managers, but in a drying and warming climate of the agricultural areas of Western Australia, land-management practices need to be able to respond to these changing conditions. The paper briefly explains the methodologies used to assess the seven soil-related themes in the Report Card and summarises the major findings. The results indicate that, for soils, the situation and outlook for our natural resources is mixed. Although there has been progress in some areas, such as managing wind and water erosion, the status and trend in many indicators of resource condition, such as soil acidity, soil compaction and water repellence, are adverse. The predicted growth in global demand for food and fibre brings many opportunities to the Western Australian agri-food sector but also challenges, especially in light of the Report Card findings. One of these challenges is our need to achieve agricultural productivity growth while ensuring our natural resources are healthy and resilient.
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Robertson, Fiona, Doug Crawford, Debra Partington, Ivanah Oliver, David Rees, Colin Aumann, Roger Armstrong, et al. "Soil organic carbon in cropping and pasture systems of Victoria, Australia." Soil Research 54, no. 1 (2016): 64. http://dx.doi.org/10.1071/sr15008.
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Increasing soil organic carbon (SOC) storage in agricultural soils through changes to management may help to mitigate rising greenhouse gas emissions and sustain agricultural productivity and environmental conditions. However, in order to improve assessment of the potential for increasing SOC storage in the agricultural lands of Victoria, Australia, further information is required on current SOC levels and how they are related to environmental conditions, soil properties and agricultural management. Therefore, we measured stocks of SOC at 615 sites in pasture and cropping systems in Victoria, encompassing eight regions, five soil orders and four management classes (continuous cropping, crop–pasture rotation, sheep or beef pasture, and dairy pasture), and explored relationships between the C stocks and environment, soil and management. The results showed an extremely wide range in SOC, from 2 to 239 t C/ha (0–30 cm). Most of this variation was attributable to climate; almost 80% of the variation in SOC stock was related to annual rainfall or vapour pressure deficit (i.e. humidity). Texture-related soil properties accounted for a small, additional amount of variation in SOC. After accounting for climate, differences in SOC between management classes were small and often not significant. Management practices such as stubble retention, minimum cultivation, perennial pasture species, rotational grazing and fertiliser inputs were not significantly related to SOC stock. The relationships between SOC and environment, soil and management were scale-dependent. Within individual regions, the apparent influence of climate and soil properties on SOC stock varied, and in some regions, much of the variation in SOC stock remained unexplained. The results suggest that, across Victoria, there is a general hierarchy of influence on SOC stock: climate > soil properties > management class > management practices.
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Poch, R. M., B. P. Thomas, R. W. Fitzpatrick, and 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, no. 4 (2009): 403. http://dx.doi.org/10.1071/sr07015.
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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.
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Curran, Timothy J., Peter J. Clarke, and Nigel W. M. Warwick. "Drought survival of Australian rainforest seedlings is influenced by species evolutionary history and soil type." Australian Journal of Botany 61, no. 1 (2013): 22. http://dx.doi.org/10.1071/bt12081.
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Water availability influences regional tree distributions in rainforests, often by affecting survival of seedlings. The occurrence of ‘dry rainforest’ species in subhumid climates has been attributed to the evolution of drought-resistant species from their mesic rainforest congeners. Many genera are found in both dry and mesic rainforest of Australia but the extent to which this is due to differential drought resistance has not been confirmed experimentally. We compared drought survival within three congeneric pairs of dry and mesic rainforest taxa in a glasshouse dry-down experiment. Soil type could also play a role, with dry rainforests mostly occurring on fine-textured soils such as loams, which have a high available water-holding capacity, compensating for lower rainfall. Hence, we grew plants in loam or sand soil. In all pairs, the dry rainforest taxon was better able to survive drought, providing support for the climate-induced evolution of a dry rainforest flora and further confirming that drought resistance of seedlings can shape tree species distributions at regional scales. Two of three pairs had higher seedling survival on basalt-derived loam soil, suggesting that such soils may aid seedling persistence during drought. Over evolutionary time, this may have resulted in the high fidelity of dry rainforest for these soils.
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Unkovich, Murray, Jeff Baldock, and Steve Marvanek. "Which crops should be included in a carbon accounting system for Australian agriculture?" Crop and Pasture Science 60, no. 7 (2009): 617. http://dx.doi.org/10.1071/cp08428.
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Dryland agriculture is both a potential source and potential sink for CO2 and other greenhouse gases. Many carbon accounting systems apply simple emissions factors to production units to estimate greenhouse gas (GHG) fluxes. However, in Australia, substantial variation in climate, soils, and management across >20 Mha of field crop sowings and >30 Mha of sown pastures in the intensive land use zone, provides substantial challenges for a national carbon accounting system, and simple emission factors are unlikely to apply across the region. In Australia a model framework has been developed that requires estimates of crop dry matter production and harvested yield as the first step to obtain carbon (residue) inputs. We use Australian Bureau of Statistics data to identify which crops would need to be included in such a carbon accounting system. Wheat, barley, lupin, and canola accounted for >80% of field crop sowings in Australia in 2006, and a total of 22 crops account for >99% of the sowing area in all States. In some States, only four or six crops can account for 99% of the cropping area. We provide a ranking of these crops for Australia and for each Australian State as a focus for the establishment of a comprehensive carbon accounting framework. Horticultural crops, although diverse, are less important in terms of total area and thus C balances for generic viticulture, vegetables, and orchard fruit crops should suffice. The dataset of crop areas presented here is the most comprehensive account of crop sowings presented in the literature and provides a useful resource for those interested in Australian agriculture. The field crop rankings presented represent only the area of crop sowings and should not be taken as rankings of importance in terms of the magnitude of all GHG fluxes. This awaits a more detailed analysis of climate, soils, and management practices across each of the regions where the crops are grown and their relationships to CO2, nitrous oxide and methane fluxes. For pastures, there is a need for more detailed, up to date, spatially explicit information on the predominant sown pasture types across the Australian cropping belt before C balances for these can be more reliably modelled at the desired spatial scale.
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Ahern, CR, MMG Weinand, and RF Isbell. "Surface soil-pH map of Queensland." Soil Research 32, no. 2 (1994): 212. http://dx.doi.org/10.1071/sr9940213.
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Surface soil pH can influence biological activity, nutrition and various chemical processes in the soil. Low pH or acidity is causing major concern in southern Australia, prompting requests for details on the extent, severity and distribution of acidic soils in Queensland. By creating a soil pH database, using an appropriate base map, rainfall isohyets and GIS technology, a coloured pH map of surface soils was produced at a 1:5000000 scale for the entire State. As most samples were from virgin or little disturbed sites, the map generally reflects naturally occurring soil pH. Developed horticultural, agricultural and fertilized pastoral areas are likely to have lower pH than that mapped. About two thirds (63.1%) of Queensland's soils have acidic surfaces, 9.5% neutral and the remaining 26.9% are alkaline. The major proportion (74%) of the > 1200 mm rainfall zone is strongly acid, and the remainder is medium acid or acid. Much of the sugar growing areas occur in this zone. Surface soil pH generally decreases as rainfall increases and to a lesser extent from subtropical to tropical climate. In addition to climate, identification of the soil type assists with predicting pH, as the organic, coarse and medium textured soils and massive earths are more likely to be acid and have low buffering capacity. Depending on the land use, such soils may require regular liming or minimizing of net acidifying practices for long term sustainability.
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Smith, Phil, Grahame Collier, and Hazel Storey. "As Aussie as Vegemite: Building the Capacity of Sustainability Educators in Australia." Australian Journal of Environmental Education 27, no. 1 (2011): 175–85. http://dx.doi.org/10.1017/s0814062600000161.
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AbstractVegemite, a thick, rich and salty product made from yeast extract, is a paste commonly spread on bread or toast in Australian households. This iconic product mirrors some of the unique aspects of this country. For example, Vegemite thinly spread is best. The population of this country is sparse across the wide lands, and the Australian environment with its thin soils, water shortages and intense climates, might also be described as spread thin. These aspects of context present challenges because Australia needs quality sustainability educators thick on the ground to deal with the many and diverse environmental issues.This paper describes the development of the Australian National Professional Development Initiative for Sustainability Educators (NPDISE) and how it was infuenced by the Australian context. Multiple challenges existed: the size of the country, its environmental conditions and rich biodiversity, distance and space between major centres, distribution of people and resources, understanding of and support for education, and three tiers of government – each with its own policies, programs and priorities. On top of this, the practice of sustainability education crosses multiple professional sectors and disciplines. All these challenges had to be taken into account.Research conducted by the Waste Management Association Australia in 2009 revealed that the needs of Australia's sustainability educators in overcoming many of these challenges were broadly consistent around Australia. This gave encouragement to the establishment of a national professional development approach for those working in the environmental education feld. This paper shows how four professional associations – Australian Association for Environmental Education, Waste Management Association Australia, Australian Water Association, and the Marine Education Society of Australasia – worked together for the frst time and approached these challenges whilst developing the NPDISE. A 1954 jingle said Vegemite would help children “grow stronger every single week”. The NPDISE represents a similar ethos with an emphasis on building the sector.
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French, Robert J., and 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, no. 11 (2005): 1169. http://dx.doi.org/10.1071/ar05088.
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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.
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Asseng, S., I. R. P. Fillery, F. X. Dunin, B. A. Keating, and H. Meinke. "Potential deep drainage under wheat crops in a Mediterranean climate. I. Temporal and spatial variability." Australian Journal of Agricultural Research 52, no. 1 (2001): 45. http://dx.doi.org/10.1071/ar99186.
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High rates of deep drainage (water loss below the root-zone) in Western Australia are contributing to groundwater recharge and secondary salinity. However, quantifying potential drainage through measurements is hampered by the high degree of complexity of these systems as a result of diverse soil types, a range of crops, different rainfall regions, and in particular the inherent season-to-season variability. Simulation models can provide the appropriate means to extrapolate across time and space. The Agricultural Production Systems Simulator (APSIM) was used to analyse deep drainage under wheat crops in the Mediterranean climate of the central Western Australian wheatbelt. In addition to rigorous model testing elsewhere, comparisons between simulated and observed soil water loss, evapotranspiration, and deep drainage for different soil types and seasons confirmed the reasonable performance of the APSIM model. The APSIM model was run with historical weather records (70–90 years) across 2 transects from the coast (high rainfall zone) to the eastern edge of the wheatbelt (low rainfall zone). Soils were classified as 5 major types: deep sand, deep loamy sand, acid loamy sand, shallow duplex (waterlogging), and clay soil (non-waterlogging). Simulations were carried out on these soil types with historical weather records, assuming current crop management and cultivars. Soil water profiles were reset each year to the lower limit of plant-available water, assuming maximum water use in the previous crop. Results stressed the high degree of seasonal variability of deep drainage ranging from 0 to 386 mm at Moora in the high rainfall region (461 mm/year average rainfall), from 0 to 296 mm at Wongan Hills in the medium rainfall region (386 mm/year average rainfall), and from 0 to 234 mm at Merredin in the low rainfall region (310 mm/year average rainfall). The largest amounts of drainage occurred in soils with lowest extractable water-holding capacities. Estimates of annual drainage varied with soil type and location. For example, average (s.d.) annual drainage at Moora, Wongan Hills, and Merredin was 134 (73), 90 (61), and 36 (43) mm on a sand, and 57 (64), 26 (43), and 4 (18) mm on a clay soil, respectively. These values are an order of magnitude higher than drainage reported elsewhere under native vegetation. When not resetting the soil each year, carry-over of water left behind in the soil reduced the water storage capacity in the subsequent year, increasing long-term average deep drainage, depending on soil type and rainfall region. The analyses revealed the extent of the excess water problem that currently threatens the sustainability of the wheat-based farming systems in Western Australia.
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Tyndale-Biscoe, C. H. "Australasian marsupials - to cherish and to hold." Reproduction, Fertility and Development 13, no. 8 (2001): 477. http://dx.doi.org/10.1071/rd01079.
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Considerable interchange of mammals between South America and Australasia occurred during the first half of the Tertiary, including the presence of placental mammals in Australia. This challenges the old assumption that the marsupial radiation in Australia was made possible by the absence of placental competition, and suggests that two properties of marsupial organization may have favoured their survival in the increasingly arid climates that developed after the separation of Australasia from Antarctica. The basal metabolic rates of marsupials are about 70% of equivalent placentals, so their maintenance requirements for energy, nitrogen and water are lower, whereas their field metabolic rates are about the same, which means that they have a greater metabolic scope to call on when active. This may have given marsupials an advantage in semi-arid environments. The lengthy and complex lactation of marsupials enables the female to exploit limited resources over an extended period without compromising the survival of the young. Both these properties of marsupials enabled them to survive the double constraints of low fertility soils and the uncertain climate of Australia throughout the Tertiary. The arrival of people was followed first by the extinction of the large marsupials and, much later, by the wholesale decline or extinction of the small-to-medium sized species. The common factor in both extinctions may have been the constraints of marsupial reproduction.
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Richter, H., A. W. Western, and F. H. S. Chiew. "The Effect of Soil and Vegetation Parameters in the ECMWF Land Surface Scheme." Journal of Hydrometeorology 5, no. 6 (December 1, 2004): 1131–46. http://dx.doi.org/10.1175/jhm-362.1.
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Abstract Numerical Weather Prediction (NWP) and climate models are sensitive to evapotranspiration at the land surface. This sensitivity requires the prediction of realistic surface moisture and heat fluxes by land surface models that provide the lower boundary condition for the atmospheric models. This paper compares simulations of a stand-alone version of the European Centre for Medium-Range Weather Forecasts (ECMWF) land surface scheme, or the Viterbo and Beljaars scheme (VB95), with various soil and vegetation parameter sets against soil moisture observations across the Murrumbidgee River catchment in southeast Australia. The study is, in part, motivated by the adoption of VB95 as the operational land surface scheme by the Australian Bureau of Meteorology in 1999. VB95 can model the temporal fluctuations in soil moisture, and therefore the moisture fluxes, fairly realistically. The monthly model latent heat flux is also fairly insensitive to soil or vegetation parameters. The VB95 soil moisture is sensitive to the soil and, to a lesser degree, the vegetation parameters. The model exhibits a significant (generally wet) bias in the absolute soil moisture that varies spatially. The use of the best Australia-wide available soils and vegetation information did not improve VB95 simulations consistently, compared with the original model parameters. Comparisons of model and observed soil moistures revealed that more realistic soil parameters are needed to reduce the model soil moisture bias. Given currently available continent-wide soils parameters, any initialization of soil moisture with observed values would likely result in significant flux errors. The soil moisture bias could be largely eliminated by using soil parameters that were derived directly from the actual soil moisture observations. Such parameters, however, are only available at very few point locations.
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Keating, B. A., and P. S. Carberry. "Emerging opportunities and challenges for Australian broadacre agriculture." Crop and Pasture Science 61, no. 4 (2010): 269. http://dx.doi.org/10.1071/cp09282.
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Agriculture globally and in Australia is at a critical juncture in its history with the current changes to input costs, commodity prices, consumption patterns and food stocks. Constraints are emerging in terms of land and water resources as well as imperatives to reduce greenhouse gas emissions. There is evidence that rates of increase in agricultural productivity are reducing, both in Australia and overseas. On top of all these drivers of change, agriculture is the sector probably most exposed to climate change, and Australian agriculture is as exposed as any in the world. Against this turbulent background, this paper explores some of the emerging opportunities and challenges in Australian agriculture. These include new products or services from agriculture such as biofuels, forest-based carbon storage in agricultural landscapes, bio-sequestration of carbon in agricultural soils, and environmental stewardship schemes that would reward farmers for nature conservation and related non-production services from farming land. Although there are situations where all these emerging opportunities may deliver benefits to both farmers and the wider community, an overall conclusion is that none of these, on their own, will transform the nature of Australian agriculture. Instead, the greatest emerging opportunity for Australian agriculture must be sought from productivity breakthroughs in the face of current and emerging constraints. This view is formed by looking through the lens of the global food production challenge which sees a demand for close to a doubling of food production by 2050 in the face of increasingly constrained land and water resources, soil degradation, increasing energy scarcity and limits on greenhouse gas release to the atmosphere. These same land, water, soil, energy and atmospheric constraints to agriculture apply in Australia and will shape both farming and the agricultural research agenda over coming decades. In the face of such national and global agronomic challenges, a significant threat looms with the skills challenge facing agricultural science in Australia. The demand for the integrative skills of agronomy appears strong but the sector has suffered from disinvestment in recent decades.
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Dawes, W., R. Ali, S. Varma, I. Emelyanova, G. Hodgson, and D. McFarlane. "Modelling the effects of climate and land cover change on groundwater recharge in south-west Western Australia." Hydrology and Earth System Sciences 16, no. 8 (August 14, 2012): 2709–22. http://dx.doi.org/10.5194/hess-16-2709-2012.
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Abstract. The groundwater resource contained within the sandy aquifers of the Swan Coastal Plain, south-west Western Australia, provides approximately 60 percent of the drinking water for the metropolitan population of Perth. Rainfall decline over the past three decades coupled with increasing water demand from a growing population has resulted in falling dam storage and groundwater levels. Projected future changes in climate across south-west Western Australia consistently show a decline in annual rainfall of between 5 and 15 percent. There is expected to be a reduction of diffuse recharge across the Swan Coastal Plain. This study aims to quantify the change in groundwater recharge in response to a range of future climate and land cover patterns across south-west Western Australia. Modelling the impact on the groundwater resource of potential climate change was achieved with a dynamically linked unsaturated/saturated groundwater model. A vertical flux manager was used in the unsaturated zone to estimate groundwater recharge using a variety of simple and complex models based on climate, land cover type (e.g. native trees, plantation, cropping, urban, wetland), soil type, and taking into account the groundwater depth. In the area centred on the city of Perth, Western Australia, the patterns of recharge change and groundwater level change are not consistent spatially, or consistently downward. In areas with land-use change, recharge rates have increased. Where rainfall has declined sufficiently, recharge rates are decreasing, and where compensating factors combine, there is little change to recharge. In the southwestern part of the study area, the patterns of groundwater recharge are dictated primarily by soil, geology and land cover. In the sand-dominated areas, there is little response to future climate change, because groundwater levels are shallow and much rainfall is rejected recharge. Where the combination of native vegetation and clayey surface soils restricts possible infiltration, recharge rates are very sensitive to reductions in rainfall. In the northern part of the study area, both climate and land cover strongly influence recharge rates. Recharge under native vegetation is minimal and is relatively higher where grazing and pasture systems have been introduced after clearing of native vegetation. In some areas, the recharge values can be reduced to almost zero, even under dryland agriculture, if the future climate becomes very dry.
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Devkota, Bikash, Md Rajibul Karim, Md Mizanur Rahman, and Hoang Bao Khoi Nguyen. "Accounting for Expansive Soil Movement in Geotechnical Design—A State-of-the-Art Review." Sustainability 14, no. 23 (November 24, 2022): 15662. http://dx.doi.org/10.3390/su142315662.
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Lightweight structures built on expansive soils are susceptible to damage caused by soil movement. Financial losses resulting from the improper design of structures on expansive soils can be significant. The interactions and failure mechanisms of different geotechnical structures constructed on such soils differ depending on the structure type, site characteristics, and climatic conditions, as the behaviour of expansive soils is influenced by moisture variations. Therefore, the performance of different geotechnical structures (e.g., lightweight footings for residential buildings) is expected to be adversely affected by climate change (especially rainfall and temperature change), as geotechnical structures are often designed to have a service life of 50–100 years. Some structures may even fail if the effect of climate change is not considered in the present design. This review aims to provide insights into problems associated with expansive soils that trigger the failure of lightweight structures, including current investigations and industry practices. This review recognises that although the soil moisture conditions govern expansive soil behaviour, limited studies have incorporated the effect of future climate changes. In addition, this review identifies the need to improve the current Australian design practice for residential footings through the inclusion of more site-specific investigations and expected climate changes.
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Hill, MJ. "Potential adaptation zones for temperate pasture species as constrained by climate: a knowledge-based logical modelling approach." Australian Journal of Agricultural Research 47, no. 7 (1996): 1095. http://dx.doi.org/10.1071/ar9961095.
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Potential adaptation zones were modelled for major temperate pasture species using climate data and knowledge-based logical rules. A GIs database was constructed using a 0.025 degree digital elevation model and the Australian Climate Surfaces to create layers of monthly mean climate data for Australia. Soil pH maps for New South Wales, Victoria, and south-eastern South Australia were digitised and added to the database. Simple models using logical operators were constructed using estimates of temperature and aridity thresholds for the main temperate pasture species. The logical models were executed using primary and derived climate layers to create raster maps of potential adaptation zones for pasture species in eastern and south-western Australia. Areas of adaptation on freehold/leasehold land were expressed relative to a potential temperate pasture adaptation zone described by the lower (arid) limit of annual legume adaptation in temperate Australia and the northern limit of lucerne adaptation. Potential adaptation within this area ranged from 66% for lucerne down to <20% for perennial ryegrass in eastern Australia, and 93% for subterranean clover down to zero for perennial ryegrass in south-western Australia. Utility of the species adaptation zones could be enhanced using soil pH maps: a zone for serradella in NSW was refined by restricting adaptation to areas of climatic suitability with low soil pH. Maps for lucerne and Mount Barker subterranean clover showed good agreement with validation data for NSW. The zones may be readily adjusted by simple changes to parameter values in the algorithms. This knowledge-based approach has potential as an aid to targeting resources for plant improvement or to provide advice for more efficient utilisation of existing commercial pasture plants.
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L. Specht, Raymond, Gloria Montenegro, and Mary E. Dettmann. "Structure and Alpha Biodiversity of Major Plant Communities in Chile, a Distant Gondwanan Relation." Journal of Environment and Ecology 6, no. 1 (June 8, 2015): 21. http://dx.doi.org/10.5296/jee.v6i1.7780.
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<p class="1"><span lang="EN-GB">The structure, growth and biodiversity of Chilean vegetation are explored from the arid north, through the Mediterranean-climate zone of Central Chile to the evergreen and semi-deciduous <em>Nothofagus</em> vegetation in the south and into the treeless wet-heath vegetation of the Magellanic islands. The northern Desert Zone has four to six genera of plants that have been recorded in Australia, while the southern vegetation reveals many relationships with the cool temperate vegetation of Australia with which Chile was conjoined in the Gondwanan assembly during the Late Mesozoic. As the physico-chemical processes that determine the structure, growth and biodiversity of plant communities on median-nutrient soils are similar in the temperate climates of Chile and Australia, similar values of Foliage Projective Cover, Leaf Area, Leaf Specific Weight and Alpha Biodiversity result.</span></p>
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Bui, Elisabeth N., Carlos E. González-Orozco, and Joseph T. Miller. "Acacia, climate, and geochemistry in Australia." Plant and Soil 381, no. 1-2 (April 26, 2014): 161–75. http://dx.doi.org/10.1007/s11104-014-2113-x.
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Mielenz, Henrike, Peter J. Thorburn, Robert H. Harris, Sally J. Officer, Guangdi Li, Graeme D. Schwenke, and Peter R. Grace. "Nitrous oxide emissions from grain production systems across a wide range of environmental conditions in eastern Australia." Soil Research 54, no. 5 (2016): 659. http://dx.doi.org/10.1071/sr15376.
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Nitrous oxide (N2O) emissions from Australian grain cropping systems are highly variable due to the large variations in soil and climate conditions and management practices under which crops are grown. Agricultural soils contribute 55% of national N2O emissions, and therefore mitigation of these emissions is important. In the present study, we explored N2O emissions, yield and emissions intensity in a range of management practices in grain crops across eastern Australia with the Agricultural Production Systems sIMulator (APSIM). The model was initially evaluated against experiments conducted at six field sites across major grain-growing regions in eastern Australia. Measured yields for all crops used in the experiments (wheat, barley, sorghum, maize, cotton, canola and chickpea) and seasonal N2O emissions were satisfactorily predicted with R2=0.93 and R2=0.91 respectively. As expected, N2O emissions and emissions intensity increased with increasing nitrogen (N) fertiliser input, whereas crop yields increased until a yield plateau was reached at a site- and crop-specific N rate. The mitigation potential of splitting N fertiliser application depended on the climate conditions and was found to be relevant only in the southern grain-growing region, where most rainfall occurs during the cropping season. Growing grain legumes in rotation with cereal crops has great potential to reduce mineral N fertiliser requirements and so N2O emissions. In general, N management strategies that maximise yields and increase N use efficiency showed the greatest promise for N2O mitigation.
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Cooke, Julia, R. H. Groves, and Julian Ash. "The distribution of Carrichtera annua in Australia: introduction, spread and probable limits." Rangeland Journal 33, no. 1 (2011): 23. http://dx.doi.org/10.1071/rj10001.
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Carrichtera annua (L.) DC. (Brassicaceae) or Ward’s Weed, a major weed of semi-arid rangelands of southern Australia, has been collected widely since its introduction early in the 20th century. Collated records were used to suggest a single site of accidental introduction in South Australia, evidence of a lag phase of ~30 years (probably due to edaphic restrictions) before rapid spread, involving infrequent long-distance human-aided dispersal across southern Australia and a relatively stable range since the 1960s. Climate and soil analyses suggest that abiotic factors limit the distribution of C. annua, with the species being restricted to areas with winter-dominated rainfall and calcareous soils. Documentation of the history of a successful invasion, including the spread and probable limits of the current distribution of a species, is important for managing invasions. This study also highlights that a single, accidental introduction can result in a long-lasting, widespread problematic weed.
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Paustian, K., ET Elliott, HP Collins, CV Cole, and EA Paul. "Use of a network of long-term experiments for analysis of soil carbon dynamics and global change: the North American model." Australian Journal of Experimental Agriculture 35, no. 7 (1995): 929. http://dx.doi.org/10.1071/ea9950929.
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Soils contain a large proportion of the carbon (C) in the terrestrial biosphere, yet the role of soils as a sink or a source of net atmospheric C flux is uncertain. In agricultural systems, soil C is highly influenced by management practices and there is considerable interest in adapting management systems to promote soil C sequestration, thereby helping to mitigate atmospheric CO2 increases. Long-term field experimental sites represent a unique source of information on soil C dynamics, and networks of such sites provide a key ingredient for making large-scale assessments of soil C change across ranges in climate and soil conditions and management regimes. Currently, there are collaborative efforts to develop such site networks in Australia, Europe, and North America. A network of long-term experiments in North America was established to provide baseline information on the effects of management (i.e. tillage, crop rotations, fertilisation, organic amendments) on soil organic matter. Historical data on soils, primary productivity, climate, and management were synthesised by scientists from the individual field sites, representing a total of 35 long-term field experiments. An additional cross-site soil sampling campaign was carried out to provide uniform comparisons of soil C and nitrogen (N), both within and across sites. Long-term field experiments are a principle component necessary for regional assessments of soil C dynamics. We describe a general methodology for combining long-term data with process-oriented simulation models and regional-level, spatially resolved databases. Such analyses are needed to assess past and present changes in soil C at regional to global scales and to make projections of the potential impacts of changes in climate, CO2, and landuse patterns on soil C in agroecosystems.
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Foreman, Paul W. "A framework for testing the influence of Aboriginal burning on grassy ecosystems in lowland, mesic south–eastern Australia." Australian Journal of Botany 64, no. 8 (2016): 626. http://dx.doi.org/10.1071/bt16081.
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The complex interactions among climate, soils, fire and humans in the biogeography of natural grasslands has long been debated in Australia. On the one hand, ecological models assume the primacy of climate and soils. On the other, Aboriginal burning is hypothesised to have altered the entire continent since before the last glacial maximum. The present paper develops a framework to test for the ‘fingerprint’ of Aboriginal burning in lowland, mesic grassy ecosystems of south-eastern Australia, using ecological theory, and the ethno-historical record. It is clear that fire-stick farming was used to promote staple roots in south-eastern Australia and, in some instances, it has been shown to influence grassland–woodland boundaries. The framework comprises the following three evidence lines: (1) archival benchmarking and palaeoecology; (2) phytoecology; and (3) ethnology and archaeology. That fire-stick farming was likely instrumental in grassland formation and maintenance must be supported by evidence that shows that ‘natural’ grasslands exist in climatically–edaphically unexpected places, that fine-scale patterns and dynamics are at least partly due to fire and that the fire regime has been influenced by Aboriginal burning. Application of the framework indicated that widespread Aboriginal burning for staple foods likely extended the area of temperate grasslands and influenced their structure and function.
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Narisma, G. T., and A. J. Pitman. "Exploring the Sensitivity of the Australian Climate to Regional Land-Cover-Change Scenarios under Increasing CO2 Concentrations and Warmer Temperatures." Earth Interactions 10, no. 7 (February 1, 2006): 1–27. http://dx.doi.org/10.1175/ei154.1.
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Abstract The potential role of the impacts of land-cover changes (LCCs) in the Australian climate is investigated within the context of increasing CO2 concentrations and temperature. Specifically, it is explored if possible scenarios for LCC can moderate or amplify CO2-induced changes in climate over Australia. The January climate of Australia is simulated under three different land-cover-change scenarios using a high-resolution regional climate model. The land-cover-change scenarios include a steady-state land cover that is equivalent to current land cover, a low-reforestation scenario that recovers approximately 25% of the trees replaced by grasslands within the last 200 yr, and a high-reforestation scenario that recovers at least 75% of the deforested regions. The model was driven by boundary conditions taken from transitory climate simulations from a general circulation model that included two climate scenarios based on two projected scenarios of CO2 concentration increase. The results show that reforestation has the potential to reduce the projected increase in Australian temperatures in 2050 and 2100 by as much as 40% and 20%, respectively. This cooling effect, however, is highly localized and occurs only in regions of reforestation. The results therefore hint that the potential of reforestation to moderate the impact of global warming may be significantly limited by the spatial scale of reforestation. In terms of deforestation, results show that any future land clearing can exacerbate the projected warming in certain regions of Australia. Carbon-related variables are also analyzed and results show that changes in net CO2 flux may be influenced more by soil respiration than by photosynthesis. The results herein encourage studies on the inclusion of land-cover-change scenarios in future climate change projection simulations of the Australian climate.