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Humphries, A. W., X. G. Zhang, K. S. McDonald, R. A. Latta e G. C. Auricht. "Persistence of diverse lucerne (Medicago sativa sspp.) germplasm under farmer management across a range of soil types in southern Australia". Australian Journal of Agricultural Research 59, n.º 2 (2008): 139. http://dx.doi.org/10.1071/ar07037.
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The persistence of a diverse group of lucerne (Medicago sativa sspp.) germplasm was evaluated under farmer management across a range of acidic and neutral-alkaline soils at 8 sites in South and Western Australia. Dryland field trials were sown in parallel with commercial lucerne paddocks being grown in rotation with cereal crops, remaining unfenced and under management by the farmer for the life of the stand. The combined differences in soil type, grazing management, and low rainfall contributed to large differences in average lucerne persistence between sites in South Australia and Western Australia. After 3 years, plant frequency (a measure of plant density used to monitor persistence) averaged 17% (at least 17 plants/m2) on the strongly acidic soils in Western Australia and 30% on the neutral-alkaline soils in South Australia (at least 30 plants/m2). Differences in persistence were attributed to the combined stresses of soil pH, drought conditions, and grazing management. Genetic correlation analyses between sites failed to show any clear patterns in the performance of entries at each site, except for a high correlation between 2 South Australian sites in close proximity. Highly winter-active germplasm was less persistent than other winter activity groups, but was higher yielding when assessed in an additional trial at Katanning, WA. Highly winter-active lucerne (class 9–10) should continue to be recommended for short (2–4 year) phases in rotation with cereals, and winter-active groups (6–8) should be recommend for longer (4–7 year) phases in rotations. The results of this evaluation are also being used to identify broadly adapted, elite genotypes in the breeding of new lucerne cultivars for the southern Australian cropping districts.
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Naidu, R., RH Merry, GJ Churchman, MJ Wright, RS Murray, RW Fitzpatrick e BA Zarcinas. "Sodicity in South Australia - a review". Soil Research 31, n.º 6 (1993): 911. http://dx.doi.org/10.1071/sr9930911.
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The current knowledge of the nature and distribution of sodic soils in South Australia is reviewed. The agriculturally developed area of South Australia lies south of latitude 32-degrees-S. and is mainly used for low intensity grazing and dry land cereal/sheep production. A high proportion of the State, including much of the high rainfall area, has soils which are sodic (>6% ESP) through a significant proportion of the profile but information on the precise nature of sodicity in these soils is limited. Where exchangeable cation data axe available, the analytical techniques used often did not precisely delineate between soluble salts in the soil and ions on exchange sites. Therefore, many of the datasets have major weaknesses and may be unreliable. Since many soils with ESP <6 also show dispersive characteristics typical of sodic soils, there is an urgent need for new sodicity studies relating to distribution and the criteria (ESP) used to identify dispersive soils. Information on the effect of sodicity on nutrient requirements of plants, especially the modern varieties, is scarce both locally and internationally, making development of management strategies for economically sustainable crop production difficult. Further, many different grades of gypsum are available in South Australia. Preliminary studies show the presence of impurities drastically influences gypsum dissolution characteristics. More effort is needed to assess the quality and reactivity of South Australian gypsum. Some effort has been directed by land managers towards reclamation and management of sodic soils by using both gypsum and lime either separately or as mixtures. However, there is neither a scientific basis for the application of gypsum-lime mixtures nor crop production data to support such management strategies.
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Webb, Ashley A., Georgina L. Kelly e Warwick J. Dougherty. "Soil governance in the agricultural landscapes of New South Wales, Australia". International Journal of Rural Law and Policy, n.º 1 (29 de março de 2015): 1–16. http://dx.doi.org/10.5130/ijrlp.i1.2015.4169.
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Soil is a valuable natural resource. In the state of New South Wales, Australia, the governance of soil has evolved since Federation in 1901. Following rapid agricultural development, and in the face of widespread soil degradation, the establishment of the Soil Conservation Service marked a turning point in the management of soil. Throughout the 20th century, advances in knowledge were translated into evolving governance frameworks that were largely reactionary but saw progressive reforms such as water pollution legislation and case studies of catchment-scale land and vegetation management. In the 21st century, significant reforms have embedded sustainable use of agricultural soils within catchment- and landscape-scale legislative and institutional frameworks. What is clear, however, is that a multitude of governance strategies and models are utilised in NSW. No single governance model is applicable to all situations because it is necessary to combine elements of several different mechanisms or instruments to achieve the most desired outcomes. Where an industry, such as the sugar industry, has taken ownership of an issue such as acid sulfate soil management, self-regulation has proven to be extremely effective. In the case of co-managing agricultural soils with other landuses, such as mining, petroleum exploration and urban development, regulation, compliance and enforcement mechanisms have been preferred. Institutional arrangements in the form of independent commissioners have also played a role. At the landscape or total catchment level, it is clear that a mix of mechanisms is required. Fundamental, however, to the successful evolution of soil governance is strategic investment in soil research and development that informs the ongoing productive use of agricultural landscapes while preventing land degradation or adverse environmental effects.
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Unkovich, Murray, Therese McBeath, Rick Llewellyn, James Hall, Vadakattu VSR Gupta e Lynne M. Macdonald. "Challenges and opportunities for grain farming on sandy soils of semi-arid south and south-eastern Australia". Soil Research 58, n.º 4 (2020): 323. http://dx.doi.org/10.1071/sr19161.
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Sandy soils make up a substantial fraction of cropping land in low rainfall (<450 mm p.a.) south and south-eastern Australia. In this paper we review the possible soil constraints to increased production on these soils in this region. Many of these soils have a very low (<3%) clay content and suffer from severe water repellency, making crop establishment and weed control problematic. Crops which do emerge are faced with uneven soil wetting and poor access to nutrients, with crop nutrition constraints exacerbated by low fertility (soil organic matter < 1%) and low cation exchange capacity. Zones of high penetration resistance appear common and have multiple causes (natural settling, cementation and traffic induced) which restrict root growth to <40 cm. Crop water use and grain yield are therefore likely to be well below the water-limited potential. Water repellency is readily diagnosed and where apparent should be the primary management target. Repellency can be mitigated through the use of furrow and other sowing technologies, along with soil wetting agents. These techniques appear to be affected by site and soil nuances and need to be refined for local soils and conditions. Once crop establishment on water repellent soils has been optimised, attention could be turned to opportunities for improving crop rooting depth through the use of deep tillage or deep ripping techniques. The required ripping depth, and how long the effects may last, are unclear and need further research, as do the most effective and efficient machinery requirements to achieve sustained deeper root growth. Crop nutrition matched to the water-limited crop yield potential is the third pillar of crop production that needs to be addressed. Low soil organic matter, low cation exchange capacity, low biological activity and limited nutrient cycling perhaps make this a greater challenge than in higher rainfall regions with finer textured soils. Interactions between nutrients in soils and fertilisers are likely to occur and make nutrient management more difficult. While amelioration (elimination) of water repellency is possible through the addition of clay to the soil surface, the opportunities for this may be restricted to the ~30% of the sandy soils of the region where clay is readily at hand. The amounts of clay required to eliminate repellency (~5%) are insufficient to significantly improve soil fertility or soil water holding capacity. More revolutionary soil amelioration treatments, involving additions and incorporation of clay and organic matter to soils offer the possibility of a more elevated crop yield plateau. Considerable research would be required to provide predictive capacity with respect to where and when these practices are effective.
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Doran-Browne, Natalie A., John Ive, Phillip Graham e Richard J. Eckard. "Carbon-neutral wool farming in south-eastern Australia". Animal Production Science 56, n.º 3 (2016): 417. http://dx.doi.org/10.1071/an15541.
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Ruminant livestock production generates higher levels of greenhouse gas emissions (GHGE) compared with other types of farming. Therefore, it is desirable to reduce or offset those emissions where possible. Although mitigation options exist that reduce ruminant GHGE through the use of feed management, flock structure or breeding management, these options only reduce the existing emissions by up to 30% whereas planting trees and subsequent carbon sequestration in trees and soil has the potential for livestock emissions to be offset in their entirety. Trees can introduce additional co-benefits that may increase production such as reduced salinity and therefore increased pasture production, shelter for animals or reduced erosion. Trees will also use more water and compete with pastures for water and light. Therefore, careful planning is required to locate trees where the co-benefits can be maximised instead of any negative trade-offs. This study analysed the carbon balance of a wool case study farm, Talaheni, in south-eastern Australia to determine if the farm was carbon neutral. The Australian National Greenhouse Gas Inventory was used to calculate GHGE and carbon stocks, with national emissions factors used where available, and otherwise figures from the IPCC methodology being used. Sources of GHGE were from livestock, energy and fuel, and carbon stocks were present in the trees and soil. The results showed that from when the farm was purchased in 1980–2012 the farm had sequestered 11 times more carbon dioxide equivalents (CO2e) in trees and soil than was produced by livestock and energy. Between 1980 and 2012 a total of 31 100 t CO2e were sequestered with 19 300 and 11 800 t CO2e in trees and soil, respectively, whereas farm emissions totalled 2800 t CO2e. There was a sufficient increase in soil carbon stocks alone to offset all GHGE at the study site. This study demonstrated that there are substantial gains to be made in soil carbon stocks where initial soils are eroded and degraded and there is the opportunity to increase soil carbon either through planting trees or introducing perennial pastures to store more carbon under pastures. Further research would be beneficial on the carbon-neutral potential of farms in more fertile, high-rainfall areas. These areas typically have higher stocking rates than the present study and would require higher levels of carbon stocks for the farm to be carbon neutral.
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Bolan, NS, RE White e MJ Hedley. "A review of the use of phosphate rocks as fertilizers for direct application in Australia and New Zealand." Australian Journal of Experimental Agriculture 30, n.º 2 (1990): 297. http://dx.doi.org/10.1071/ea9900297.
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Field trials in New Zealand have shown that reactive phosphate rocks (RPRs) can be as effective as soluble P fertilisers, per kg of P applied, on permanent pastures that have a soil pH<6.0 (in water) and a mean annual rainfall >800 mm. Whereas RPRs such as North Carolina, Sechura, Gafsa and Chatham Rise have been evaluated on permanent pastures in New Zealand, most Australian field trials have examined unreactive PRs such as Christmas Island A and C grade, Nauru and Duchess, using annual plant species. Only in recent experiments has an RPR, North Carolina, been examined. Except on the highly leached sands in southern and south-western Australia, both reactive and unreactive PRs have shown a low effectiveness relative to superphosphate. In addition to chemical reactivity, other factors may contribute to the difference in the observed agronomic effectiveness of PRs in Australia and New Zealand. Generally, PRs have been evaluated on soils of lower pH, higher pH buffering capacity (as measured by titratable acidity) and higher P status in New Zealand than in Australia. Rainfall is more evenly distributed throughout the year on New Zealand pastures than in Australia where the soil surface dries out between rainfall events. Dry conditions reduce the rate at which soil acid diffuses to a PR granule and dissolution products diffuse away. Even when pH and soil moisture are favourable, the release of P from PR is slow and more suited to permanent pasture (i.e. the conditions usually used to evaluate PRs in New Zealand) than to the annual pastures or crops used in most Australian trials. Based on the criteria of soil pH<6.0 and mean annual rainfall >800 mm, it is estimated that the potentially suitable area for RPRs on pasture in New Zealand is about 8 million ha. Extending this analysis to Australia, but excluding the seasonal rainfall areas of northern and south-western Australia, the potentially suitable area is about 13 million ha. In New Zealand, many of the soils in the North and South Islands satisfy both the pH and rainfall criteria. However, suitable areas in Australia are confined mainly to the coastal and tableland areas of New South Wales and eastern Victoria, and within these areas the actual effectiveness of RPR will depend markedly on soil management and the distribution of annual rainfall. Further research on RPR use should be focused on these areas.
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Scott, B. J., A. M. Ridley e M. K. Conyers. "Management of soil acidity in long-term pastures of south-eastern Australia: a review". Australian Journal of Experimental Agriculture 40, n.º 8 (2000): 1173. http://dx.doi.org/10.1071/ea00014.
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Acidification of non arable soils under long-term pasture presents a major agricultural problem in the high rainfall areas (≥600 mm/year) of central and southern New South Wales and north-eastern Victoria. Some of these soils were already strongly acid to depth before agriculture. Evidence suggests that persistence of pasture species tolerant of acidic soils is being affected adversely on a number of severely acidic soils. Acidification processes are well understood but the capacity for grazing enterprises to pay for amendment by lime application is a major constraint in long-term pasture areas. In addition, soil acidification is likely to have substantial off-site effects on water quantity and quality and as a result, on dryland salinity. However, there is a paucity of scientific evidence to link soil acidity and dryland salinity in this way. Production from a grazing enterprise can be maintained by selecting plants for tolerance of acidity, surface application of lime or a combination of both. Responses by subterranean clover, lucerne and perennial grass (mainly phalaris and cocksfoot)-based pastures to incorporated lime are reported, but there is limited evidence of responses to surface applied lime. The movement of the lime effect into the soil from surface application is suggested as a major factor in controlling lime responses by plants. There is a need for more confidence in the benefits of topdressed lime in non arable soils before producers are likely to adopt the practice. High subsurface acidity in many soils is a major limitation to the range of species that can be grown. In the longer term, the use of lime may remove constraints on the use of productive species such as lucerne. Other options for acidic soils where slope is less than 10% are for the grazing system to be modified or intensified, or for crop or horticultural production. Costs of lime could be justified through more profitable enterprises than traditional grazing operations. Low input systems based on native grasses are intrinsically appealing, however, this is only possible where a premium is paid for such produce (such as super fine wool). Forestry is an option where suitable land and infrastructure are present and should slow soil acidification and minimise off-site impacts. Land retirement may be a useful option for some parts of the landscape that contribute disproportionately to environmental problems. Private and government funded land retirement may have a role to play.
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Adcock, D., A. M. McNeill, G. K. McDonald e R. D. Armstrong. "Subsoil constraints to crop production on neutral and alkaline soils in south-eastern Australia: a review of current knowledge and management strategies". Australian Journal of Experimental Agriculture 47, n.º 11 (2007): 1245. http://dx.doi.org/10.1071/ea06250.
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Crop yield variability and productivity below potential yield on neutral and alkaline soils in the semiarid Mediterranean-type environments of south-eastern Australia have been attributed, in part, to variable rooting depth and incomplete soil water extraction caused by physical and chemical characteristics of soil horizons below the surface. In this review these characteristics are referred to as subsoil constraints. This document reviews current information concerning subsoil constraints typical of neutral and alkaline soils in south-eastern Australia, principally salinity, sodicity, dense soils with high penetration resistance, waterlogging, nutrient deficiencies and ion toxicities. The review focuses on information from Australia (published and unpublished), using overseas data only where no suitable Australian data is available. An assessment of the effectiveness of current management options to address subsoil constraints is provided. These options are broadly grouped into three categories: (i) amelioration strategies, such as deep ripping, gypsum application or the use of polyacrylamides to reduce sodicity and/or bulk density, deep placement of nutrients or organic matter to overcome subsoil nutrient deficiencies or the growing of ‘primer’ crops to naturally ameliorate the soil; (ii) breeding initiatives for increased crop tolerance to toxicities such as salt and boron; and (iii) avoidance through appropriate agronomic or agro-engineering solutions. The review highlights difficulties associated with identifying the impact of any single subsoil constraint to crop production on neutral and alkaline soils in south-eastern Australia, given that multiple constraints may be present. Difficulty in clearly ranking the relative effect of particular subsoil constraints on crop production (either between constraints or in relation to other edaphic and biological factors) limits current ability to develop targeted solutions designed to overcome these constraints. Furthermore, it is recognised that the task is complicated by spatial and temporal variability of soil physicochemical properties and nutrient availability, as well as other factors such as disease and drought stress. Nevertheless, knowledge of the relative importance of particular subsoil constraints to crop production, and an assessment of impact on crop productivity, are deemed critical to the development of potential management solutions for these neutral to alkaline soils.
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Eyles, Alieta, Garth Coghlan, Marcus Hardie, Mark Hovenden e Kerry Bridle. "Soil carbon sequestration in cool-temperate dryland pastures: mechanisms and management options". Soil Research 53, n.º 4 (2015): 349. http://dx.doi.org/10.1071/sr14062.
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Permanent pastures, which include sown, native and naturalised pastures, account for 4.3 Mha (56%) of the national land use in Australia. Given their extent, pastures are of great interest with respect to their potential to influence national carbon (C) budgets and CO2 mitigation. Increasing soil organic C (SOC) mitigates greenhouse gases while providing other benefits such as pasture productivity, soil health and ecosystem services. Several management approaches have been recommended to increase C sequestration in pasture-based systems; however, results have proved variable and often contradictory between sites and years. Here, we present an overview of the processes and mechanisms responsible for C sequestration in permanent pastures. In addition, we discuss the merits of traditional and emerging pasture-management practices for increasing SOC in pastures, with a focus on dryland pasture systems of south-eastern Australia. We conclude by summarising the knowledge gaps and research priorities for soil C-sequestration research in dryland pastures. Our review confirms that soils under a range of pasture types have considerable potential for sequestration of atmospheric CO2 in Australia, and that the magnitude of this potential can be greatly modified by pasture-management practices. Although the shortage of long-term studies under Australian conditions limits our ability to predict the potential of various management approaches to sequester soil C, our review indicates that prevention of erosion through maintenance of groundcover and adoption of options that promote deep C sequestration are likely to confer broad-scale maintenance or increases in SOC in pasture soils over a decade or longer. We acknowledge that the evidence is limited; therefore, confidence in the recommended practices in different locations and climates is largely unknown.
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Kelly, B., C. Allan e B. P. Wilson. "Corrigendum to: Soil indicators and their use by farmers in the Billabong Catchment, southern New South Wales". Soil Research 47, n.º 3 (2009): 340. http://dx.doi.org/10.1071/sr08033_co.
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'Soil health' programs and projects in Australia's agricultural districts are designed to influence farmers' management behaviours, usually to produce better outcomes for production, conservation, and sustainability. These programs usually examine soil management practices from a soil science perspective, but how soils are understood by farmers, and how that understanding informs their farm management decisions, is poorly documented. The research presented in this paper sought to better understand how dryland farmers in the Billabong catchment of southern New South Wales use soil indicators to inform their management decisions. Thematic content analysis of transcripts of semi-structured, face-to-face interviews with farmers suggest several themes that have implications for soil scientists and other professionals wishing to promote soil health in the dryland farming regions of south-eastern Australia. In particular, all soil indicators, including those related to soil 'health', need to relate to some clear, practical use to farmers if they are to be used in farm decision making. This research highlights a reliance of the participants of this research on agronomists. Reliance on agronomists for soil management decisions may result in increasing loss of connectivity between farmers and their land. If this reflects a wider trend, soil health projects may need to consider where best to direct their capacity-building activities, and/or how to re-empower individual farmers.
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Tiller, KG, LH Smith e RH Merry. "Accessions of atmospheric dust east of Adelaide, South Australia, and the implications for pedogenesis". Soil Research 25, n.º 1 (1987): 43. http://dx.doi.org/10.1071/sr9870043.
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Atmospheric dust and rainfall were collected at 19 locations within a 90 x 10 km study area extending eastwards from the coast near Adelaide, South Australia. Monthly collections for up to 3 years established seasonal and regional trends in fallout of particulate matter. Fallout was highest in the area of highest rainfall, but correlation of monthly rainfall with fallout was generally not statistically significant. The amount of dust collected was higher under tree foliage than in adjacent open space. Annual accession of atmospheric dust within this urban-rural transect was in the range of 5-10 t km-2 but the occasional severe dust storm could contribute about half the annual rate. These accretions of dust to the landscape, 2.5-5 mm per 1000 years, were about one hundredth of the recommended soil loss tolerance adopted in many studies of soil erosion, and thus unlikely to contribute significantly to models developed for soil loss on that basis. Dust accessions were, however, similar to estimates of rates of soil formation or profile deepening on resistant rocks of 1-5 mm per 1000 years which may be appropriate to conditions in southern Australia. Incorporation of such accessions into existing soils would be difficult to identify yet may provide a significant factor in pedogenesis in the higher rainfall areas. The low rates of soil development in many Australian landscapes, with contribution from both weathering and eolian dust inputs, would encourage the adoption of soil loss tolerances in soil erosion management that are orders of magnitude lower than those commonly accepted.
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Mitchell, M. L., M. R. McCaskill e R. D. Armstrong. "Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia". Crop and Pasture Science 70, n.º 12 (2019): 1044. http://dx.doi.org/10.1071/cp19217.
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Approximately 3.1 Mha (22%) of the agricultural area of south-eastern Australia can be classified as native pasture. There is the assumption that, owing to the widespread occurrence of low-fertility soils in Australia, native grass species do not respond to increased phosphorus (P) fertility. Currently, there are no industry recommendations of target soil-test P values for native-grass-based pastures. This paper reviews the responses of perennial native pasture species endemic to south-eastern Australia to P application in controlled environments, surveys, replicated experiments and paired-paddock trials. Eighty-seven site-years of trial data where different levels of P were applied, conducted over the last two decades, on native-based pastures in south-eastern Australia are reviewed. Data indicate that application of P fertilisers to native grass pastures can increase dry matter (DM) production and maintain pasture stability. However, minimum targets for herbage mass (800 kg DM/ha) and groundcover (80%) are required to ensure persistence of perennial native grasses. Stocking rates also need to match carrying capacity of the pasture. Based on previous research, we recommend target soil-test (Olsen; 0–10 cm) P levels for fertility-tolerant native grass pastures, based on Microlaena stipoides, Rytidosperma caespitosum, R. fulvum, R. richardsonii, R. duttonianum and R. racemosum, of 10–13 mg/kg, whereas for pastures based on fertility-intolerant species such as Themeda triandra, lower levels of <6 mg/kg are required to ensure botanical stability.
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Cock, GJ. "Soil structural conditions of vineyards under two soil management systems". Australian Journal of Experimental Agriculture 25, n.º 2 (1985): 450. http://dx.doi.org/10.1071/ea9850450.
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The soil structural conditions of two management systems of vineyard soil on Barmera Sandy Loam in the Riverland of South Australia were compared. Three years of zero cultivation and weed mulching were compared with long term winter cropping and cultivation between vines. Significant increases in 1 mm dry aggregates, aggregate stability and percentage of large pores were measured under zero tillage. Significant reductions also occurred for bulk density and penetration resistance of the 6-12 cm layer of the zero-tilled soil. The results suggest that infiltration, aeration and root growth of vines would improve under a long-term program of zero tillage and weed mulching.
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McDonald, G. K., E. Tavakkoli, D. Cozzolino, K. Banas, M. Derrien e P. Rengasamy. "A survey of total and dissolved organic carbon in alkaline soils of southern Australia". Soil Research 55, n.º 7 (2017): 617. http://dx.doi.org/10.1071/sr16237.
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Dissolved organic carbon (DOC) is important to microbial activity and nutrient cycling, and its concentration is sensitive to pH. Despite the importance of alkaline soils to agricultural production in southern Australia, few studies have documented the concentrations of soil organic carbon (C) and DOC or described the effects of soil properties and management practices on DOC in these soils. A survey of 33 paddocks from the Eyre Peninsula and mid-North regions of South Australia and north-western Victoria demonstrated significant variation in pH, soil organic C and DOC. Carbon stocks in the surface 30cm were 40–55tC/ha and were lowest in paddocks from Victoria. Soils from South Australia had higher DOC concentrations in the top 20cm than soils from Victoria. Principal component analysis suggested variation in DOC was increased by high pH, electric conductivity and the concentration of exchangeable Na, and was reduced by the concentration of exchangeable Ca and clay content. Mid-infrared Fourier transform infrared spectroscopy identified regional differences in the composition of soil organic C, with high amounts of charcoal in Eyre Peninsula soils. Farm management practices had little effect on soil organic C but influenced DOC. Grain yield and DOC concentration were inversely related across and within regions which appeared to be related to the intensity of cropping having opposite influences on yield and DOC. Compared with international data, DOC concentrations were high relative to the amount of soil organic C and, in contrast to many previous studies, DOC in all regions increased with depth.
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Farquharson, R. J., G. D. Schwenke e J. D. Mullen. "Should we manage soil organic carbon in Vertosols in the northern grains region of Australia?" Australian Journal of Experimental Agriculture 43, n.º 3 (2003): 261. http://dx.doi.org/10.1071/ea00163.
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Two issues prompted this paper. The first was the measured soil organic carbon decline in fertile northern Australian soils under continual cropping using traditional management practices. We wanted to see whether it was theoretically possible to maintain or improve soil organic carbon concentrations with modern management recommendations. The second was the debate about use of sustainability indicators for on-farm management, so we looked at soil organic carbon as a potential indicator of soil health and investigated whether it was useful in making on-farm crop decisions. The analytical results indicated first that theoretically the observed decline in soil organic carbon concentrations in some northern cracking clay soils can be halted and reversed under continuous cropping sequences by using best practice management. Second, the results and associated discussion give some support to the use of soil organic carbon as a sustainability indicator for soil health. There was a consistent correlation between crop input decisions (fertilisation, stubble management, tillage), outputs (yield and profits) and outcomes (change in soil organic carbon content) in the short and longer term. And this relationship depended to some extent on whether the existing soil organic carbon status was low, medium or high. A stock dynamics relationship is one where the change in a stock (such as soil organic carbon) through time is related not only to the management decisions made and other random influences (such as climatic effects), but also to the concentration or level of the stock itself in a previous time period. Against such a requirement, soil organic carbon was found to be a reasonable measure. However, the inaccuracy in measuring soil organic carbon in the paddock mitigates the potential benefit shown in this analysis of using soil organic carbon as a sustainability indicator.These results are based on a simulation model (APSIM) calibrated for a cracking clay (Vertosol) soil typical of much of the intensively-cropped slopes and plains region of northern New South Wales and southern Queensland, and need to be interpreted in this light. There are large areas of such soils in north-western New South Wales; however, many of these experience lower rainfalls and plant-available soil water capacities than in this case, and the importance of these characteristics must also be considered.
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Palmer, Jeda, Peter J. Thorburn, Elizabeth A. Meier, Jody S. Biggs, Brett Whelan, Kanika Singh e David N. Eyre. "Can management practices provide greenhouse gas abatement in grain farms in New South Wales, Australia?" Crop and Pasture Science 68, n.º 4 (2017): 390. http://dx.doi.org/10.1071/cp17026.
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Greenhouse gas abatement in the agricultural cropping industry can be achieved by employing management practices that sequester soil carbon (C) or minimise nitrous oxide (N2O) emissions from soils. However, C sequestration stimulates N2O emissions, making the net greenhouse-gas abatement potential of management practices difficult to predict. We studied land-management practices that have potential to mitigate greenhouse gas emissions by increasing soil C storage and/or decreasing soil N2O emissions for a diverse range of broadacre grain cropping sites in New South Wales. Carbon sequestration and N2O emissions were simulated with the Agricultural Production Systems Simulator (APSIM) for a baseline crop-management scenario and alternative scenarios representing management practices for greenhouse gas abatement, for 15 rainfed or irrigated sites. The global warming potential of the scenarios was quantified at 25 and 100 years after commencement of the alternative practices. Soil C and N2O emissions were predicted to increase with the use of practices that increased organic matter additions to the soil (e.g. adding a summer crop to the rotation). However, in only a few cases did the increase in soil C storage counter the N2O emissions sufficiently to provide net greenhouse gas abatement. For rainfed sites, inclusion of a summer crop and/or a pasture in the rotation was predicted to provide greenhouse gas abatement after 25 years, whereas after 100 years, only practices that included a summer crop provided abatement for some sites. For irrigated sites after 25 years, practices that reduced N fertiliser rate while retaining stubble were predicted to provide small abatement, and practices that included a summer crop provided abatement for some sites. After 100 years, practices likely to provide abatement included those that reduced N2O emissions, such as reducing N fertiliser rate. These findings suggest that a few management practices are likely to abate greenhouse gas emissions across New South Wales grain production sites and that these practices differ for irrigated and rainfed sites.
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Harries, Martin, Ken C. Flower e Craig A. Scanlan. "Sustainability of nutrient management in grain production systems of south-west Australia". Crop and Pasture Science 72, n.º 3 (2021): 197. http://dx.doi.org/10.1071/cp20403.
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Balancing nutrient inputs and exports is essential to maintaining soil fertility in rainfed crop and pasture farming systems. Soil nutrient balances of land used for crop and pasture production in the south-west of Western Australia were assessed through survey data comprising biophysical measurements and farm management records (2010–15) across 184 fields spanning 14 Mha. Key findings were that nitrogen (N) inputs via fertiliser or biological N2 fixation in 60% of fields, and potassium (K) inputs in 90% of fields, were inadequate to balance exports despite increases in fertiliser usage and adjustments to fertiliser inputs based on rotations. Phosphorus (P) and sulfur (S) balances were positive in most fields, with only 5% returning losses >5 kg P or 7 kg S/ha. Within each of the three agroecological zones of the survey, fields that had two legume crops (or pastures) in 5 years (i.e. 40% legumes) maintained a positive N balance. At the mean legume inclusion rate observed of 20% a positive partial N budget was still observed for the Northern Agricultural Region (NAR) of 2.8 kg N/ha.year, whereas balances were negative within the Central Agricultural Region (CAR) by 7.0 kg N/ha.year, and the Southern Agricultural Region (SAR) by 15.5 kg N/ha.year. Hence, N budgets in the CAR and SAR were negative by the amount of N removed in ~0.5 t wheat grain, and continuation of current practices in CAR and SAR fields will lead to declining soil fertility. Maintenance of N in the NAR was achieved by using amounts of fertiliser N similar to other regions while harvesting less grain. The ratio of fertiliser N to legume-fixed N added to the soil in the NAR was twice that of the other regions. Across all regions, the ratio of fertiliser N to legume-fixed N added to the soil averaged ~4.0:1, a major change from earlier estimates in this region of 1:20 under ley farming systems. The low contribution of legume N was due to the decline in legume inclusion rate (now 20%), the low legume content in pastures, particularly in the NAR, and improved harvest index of lupin (Lupinus angustifolius), the most frequently grown grain legume species. Further quantifications of the effects of changing farming systems on nutrient balances are required to assess the balances more accurately, thereby ensuring that soil fertility is maintained, especially because systems have altered towards more intensive cropping with reduced legume production.
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Cochrane, HR, G. Scholz e AME Vanvreswyk. "Sodic soils in Western Australia". Soil Research 32, n.º 3 (1994): 359. http://dx.doi.org/10.1071/sr9940359.
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Sodic soils are common throughout Western Australia, particularly in the south-west agricultural area where they occur mainly as duplex or gradational profiles. Soils with sodic properties are dominant in 26% of the state; saline-sodic sediments and soils in intermittent streams, lakes and estuarine plains occupy a further 5%. Sodic soils are moderately common throughout the south and western portion of the rangeland areas (38% of the state). The south-west coastal sands and the desert and rangeland soils to the north and east of the state are rarely sodic. Although sodicity has been recognized as a discrete problem in W.A. soils since the 1920s, the extent and severity of sodicity has been satisfactorily described only for small areas of the state and most land managers are unaware of the role sodicity plays in limiting the productivity of their soils. Sodicity is implicated in a diversity of problems for both agricultural and non-agricultural uses of Western Australian soils. Subsoil impermeability is probably the most widespread of these, but no comprehensive, quantitative assessment of the influence of exchangeable sodium on subsoil properties has been undertaken. Topsoil sodicity is much less extensive but can severely restrict land productivity, particularly on sandy loam and finer textured soils which set hard when dry. The physical behaviour of Western Australian topsoils cannot usefully be predicted from measurements of exchangeable sodium alone because soils differ so greatly in their response to changing exchangeable sodium. Some remain structurally stable at ESP values >15 while others are so 'sodium-sensitive' that they exhibit highly dispersive behaviour at ESP values as low as 2%. Land values over much of the dryland farming and pastoral areas of W.A. do not justify sustained use of amendments which would reduce soil exchangeable sodium contents. Efficient management of sodic soils in these areas must rely on the prevention of degradation and the use of biological and physical means to maintain adequate soil physical properties. Effective restoration of degraded sodic soils, however, often does require application of inorganic amendments in combination with tillage to initiate structural recovery. Sodicity is currently not considered to be a problem at any of the three main irrigation areas in W.A., but all have sodic soil within their potentially irrigable lands, which may limit their future expansion.
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Wilson, Brian R., Ivor Growns e John Lemon. "Scattered native trees and soil patterns in grazing land on the Northern Tablelands of New South Wales, Australia". Soil Research 45, n.º 3 (2007): 199. http://dx.doi.org/10.1071/sr07019.
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Over large areas of south-eastern Australia, the original cover of native woodland has been extensively cleared or modified, and what remains is often characterised by scattered trees beneath which the ground-storey vegetation is largely grazed or otherwise managed. This study investigated the influence of scattered Blakely’s red gum (Eucalyptus blakelyi) trees on both near-surface and deeper soil layers in temperate grazed pastures on the Northern Tablelands of New South Wales, Australia. A significant canopy effect was observed with elevated soil pH, carbon, and nutrient status inside the tree canopy indicating soil enrichment in a zone around the tree. This effect, however, was largely restricted to the surface (0–0.20 m) soil layers. Chloride concentrations were elevated near to trees but only in the deeper soil layers, suggesting that a modified water use and deep drainage mechanism occurred near the trees. Close to the tree, however, a significant acidification was observed between 0.40–0.60 m depth in the soil, without any obvious depletion in other soil element concentrations. It is concluded that this acidification provides strong evidence in support of a ‘biological pumping’ mechanism that has been proposed elsewhere. Key questions remain as to the management implications of these results, whether the subsurface acidification that was observed is common among native Australian trees, if it might be persistent through time, and if this might be a soil issue that requires management.
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Xu, R. K., D. R. Coventry, A. Farhoodi e J. E. Schultz. "Soil acidification as influenced by crop rotations, stubble management, and application of nitrogenous fertiliser, Tarlee, South Australia". Soil Research 40, n.º 3 (2002): 483. http://dx.doi.org/10.1071/sr00104.
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Soil acidification, as influenced by N fertiliser, stubble management, and crop rotations, was investigated using soil samples from a long-term rotation trial at Tarlee, South Australia. With the effects of combination of treatment inputs (wheat–lupin, stubble retention and N-fertiliser application), the pHCa (0–10 cm depth) declined from the starting value of 6.12 to 4.50 after a 14-year period. All of the treatments caused the soil pH to decrease. The mean acidification rates for the period 1978–1992 varied from 0.5 to 2.22 kmol H+/ha.year for different treatments. Although the rainfall at Tarlee (483 mm) is not sufficient to cause regular drainage events, it is likely that downward movement of NO3– in the soil profile has caused acidification in the surface soil. Also the retention of stubble caused more acidification than where there was regular stubble burning or removal. The acidification resulted in an increase in soil exchangeable Al and Mn and extractable Al and Mn, and the decrease in soil exchangeable base cations. The values for soluble Al (extracted in CaCl2) in 1992 were 1.58 and 2.45 mg/kg (0–10 cm depth) for the wheat–bean and wheat–lupin rotations, but the percentage of Al in the ECEC was low. It is not known whether this acidity has any impact on yields of field crops at this stage. But with soluble Al and the percentage of Al in ECEC increasing, it is possible that Al toxicity may occur in the high input-output cropping soils in South Australia. acidity, pH, aluminium, manganese.
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Trolio, R., A. Bath, C. Gordon, R. Walker e A. Wyber. "Operational management of Naegleria spp. in drinking water supplies in Western Australia". Water Supply 8, n.º 2 (1 de julho de 2008): 207–15. http://dx.doi.org/10.2166/ws.2008.063.
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Naegleria fowleri is a free-living amoeboflagellate inhabiting soil and water that can cause Primary Amoebic Meningoencephalitis (PAM), a rare and sometimes fatal disease. In Australia, the amoeba typically inhabits drinking water supplies that have consistent water temperatures above 20°C. The incidence of PAM is widespread in Australia, with reports from South Australia, Western Australia, New South Wales and Queensland. One of the key issues for water utilities is the potential widespread distribution of N. fowleri and its ability to infect and re-infect drinking water supplies. In Western Australia, the majority of drinking water supplies are operated by the Water Corporation. This paper describes the conditions under which Naegleria spp. have been detected and describes the operational methods employed by the Water Corporation to control and mitigate Naegleria in public drinking water supplies.
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Rabbi, S. M. Fazle, Matthew Tighe, Annette Cowie, Brian R. Wilson, Graeme Schwenke, Malem Mcleod, Warwick Badgery e Jeff Baldock. "The relationships between land uses, soil management practices, and soil carbon fractions in South Eastern Australia". Agriculture, Ecosystems & Environment 197 (dezembro de 2014): 41–52. http://dx.doi.org/10.1016/j.agee.2014.06.020.
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Macdonald, Lynne M., Tim Herrmann e Jeffrey A. Baldock. "Combining management based indices with environmental parameters to explain regional variation in soil carbon under dryland cropping in South Australia". Soil Research 51, n.º 8 (2013): 738. http://dx.doi.org/10.1071/sr13156.
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Identifying drivers of variation in soil organic carbon (OC) at a regional scale is often hampered by a lack of historical management information. Focusing on red-brown-earth soils (Chromosol) under dryland agriculture in the Mid-North and Eyre Peninsula of South Australia, our aims were 2-fold: (i) to provide a baseline of soil OC stocks (0.3 m) and OC fractions (mid-infrared predictions of particulate, humus, and resistant OC in 0.1 m samples) in cropping and crop-pasture systems; and (ii) to evaluate whether the inclusion of management-based indices could assist in explaining regional-level variation in OC stocks and fractions. Soil OC stocks in both regions varied ~20 Mg ha–1, with higher OC stocks in the Mid-North (38 Mg ha–1) than the Eyre Peninsula (29.1 Mg ha–1). The humus OC fraction was the dominant fraction, while the particulate OC was the most variable. Environmental variables only partially explained soil OC variability, with vapour pressure deficit (VPD) offering the greatest potential and likely acting as an integrator of temperature and moisture on plant growth and decomposition processes. Differences between broad-scale cropping and crop–pasture systems were limited. In the Mid-North, variability in soil OC stocks and fractions was high, and could not be explained by environmental or management variables. Higher soil OC concentrations (0.1 m) in the Eyre Peninsula cropping than crop–pasture soils were largely accounted for in the particulate OC fraction and are therefore unlikely to represent a long-term stable OC pool. Use of the management data in index format added some explanatory power to the variability in OC stocks over the main environmental variables (VPD, slope) within the Eyre Peninsula cropping soils only. In the wider context, the management data were useful in interpreting differences between regional findings and highlighted difficulties in using uninformed, broad-scale management categories.
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Cox, J. W., C. A. Kirkby, D. J. Chittleborough, L. J. Smythe e N. K. Fleming. "Mobility of phosphorus through intact soil cores collected from the Adelaide Hills, South Australia". Soil Research 38, n.º 5 (2000): 973. http://dx.doi.org/10.1071/sr99125.
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Intact cores were collected from a variety of soils in the Adelaide Hills, South Australia, and tested for phosphorus retention and mobility (P in drainage) under various rainfall intensities (5, 25, and 50 mm/h). Phosphorus mobility was high in soils with significant macropore structure. However, all soils exhibited some degree of preferential flow of P, including the heavy-textured soils with high P adsorption that were not P saturated. A phosphorus adsorption index based only on the chemical properties of the soil did not accurately predict the mobility of P through soils with macroporosity. A phosphorus mobility index was developed encompassing both soil chemical and physical parameters. Results showed the sandy soils, and the loams over clays with high macroporosity that are located in the more elevated parts of the Adelaide hills, are most susceptible to P leaching. Management to reduce P loss to groundwater, streams, or surface water storages must aim to increase the residence time of P within soils and thereby allow mineral and organic fractions time to sorb P. Phosphorus loss through wet soils was significantly less than P loss through dry soils with high macroporosity. Application of P fertiliser to soils with high macroporosity may need to be delayed until later in the growing season than is currently practised.
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Johnston, W. H., Meredith L. Mitchell, T. B. Koen, W. E. Mulham e D. B. Waterhouse. "LIGULE: An evaluation of indigenous perennial grasses for dryland salinity management in south-eastern Australia. 1. A base germplasm collection". Australian Journal of Agricultural Research 52, n.º 3 (2001): 343. http://dx.doi.org/10.1071/ar99140.
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This paper reports on the collection phase of a research program which aimed to identify Australian native grasses that may be useful for pastoral purposes and for controlling land degradation on hill-lands in the high (>500 mm) rainfall zone of south-eastern Australia. Live plants of 37 target species were collected along a number of transects, and at specific locations, in New South Wales and Victoria. The collection sites were generally along public roads, and were chosen for their vegetation diversity. Each collection site was marked on a 1: 250000 topographic map, and detailed notes were taken of the native vegetation, geology, soil types, land use, and other features. Surface (00—10 cm) soil samples were collected at most sites and analysed for phosphorus, pH CaCl 2 , electrical conductivity, and particle size distribution. A total of 807 accessions were collected from 210 locations. At most collection sites, soils were acidic (median pH 5.6); soil phosphorus (Olsen) was in the low range (<8.5 mg/kg); and the target genera occurred with a low frequency (half of the sites yielded 3 accessions or less). Although genera collected in the study could be ranked on the basis of the mean pH of their collection sites, they all tolerated a considerable soil pH range (of about 2mp;mdash;5 pH units). Allowing root and shoot growth to recommence by growing collected plants for a short period in coarse sand considerably improved establishment success. Accessions collected in this study will be further evaluated.
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Mackenzie, D. E., e A. G. Christy. "The role of soil chemistry in wine grape quality and sustainable soil management in vineyards". Water Science and Technology 51, n.º 1 (1 de janeiro de 2005): 27–37. http://dx.doi.org/10.2166/wst.2005.0004.
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This study aimed to establish if there is any evidence that soil mineralogical and/or chemical composition influence the composition and quality of wine grapes. In the initial phase of the study, soils and grapes were sampled in two riesling vineyards in South Australia. Soils were analysed for a wide range of total major and trace elements; soil cation extracts and grape juices were analysed for 27 trace elements by ICP-MS and ICP-AES. The results show that grape juice properties such as Baumé and titratable acidity (TA) are clearly correlated with several plant-available trace elements in the soil. Most notable of these are Ca, Sr, Ba, Pb and Si. Soil clay content also plays a (lesser) role. The cations Ca, Sr, Ba and Pb are closely similar to one another in their relationships to Baumé and TA, strongly indicating that the correlations are real. It is evident from our results that soil cation chemistry does indeed have an influence on wine grape composition. Such knowledge has the potential to be used in better tailoring grape varieties to soils, and in managing – or modifying – soils for optimum viticultural results and better wines in a more sustainable way.
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Kelly, B., C. Allan e B. P. Wilson. "Soil indicators and their use by farmers in the Billabong Catchment, southern New South Wales". Soil Research 47, n.º 2 (2009): 234. http://dx.doi.org/10.1071/sr08033.
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‘Soil health’ programs and projects in Australia’s agricultural districts are designed to influence farmers’ management behaviours, usually to produce better outcomes for production, conservation, and sustainability. These programs usually examine soil management practices from a soil science perspective, but how soils are understood by farmers, and how that understanding informs their farm management decisions, is poorly documented. The research presented in this paper sought to better understand how dryland farmers in the Billabong catchment of southern New South Wales use soil indicators to inform their management decisions. Thematic content analysis of transcripts of semi-structured, face-to-face interviews with farmers suggest several themes that have implications for soil scientists and other professionals wishing to promote soil health in the dryland farming regions of south-eastern Australia. In particular, all soil indicators, including those related to soil ‘health’, need to relate to some clear, practical use to farmers if they are to be used in farm decision making. This research highlights a reliance of the participants of this research on agronomists. Reliance on agronomists for soil management decisions may result in increasing loss of connectivity between farmers and their land. If this reflects a wider trend, soil health projects may need to consider where best to direct their capacity-building activities, and/or how to re-empower individual farmers.
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Wills, Timothy J., e Jennifer Read. "Effects of heat and smoke on germination of soil-stored seed in a south-eastern Australian sand heathland". Australian Journal of Botany 50, n.º 2 (2002): 197. http://dx.doi.org/10.1071/bt01017.
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Various fire-related agents, including heat, smoke, ash and charred wood, have been shown to break dormancy and promote germination of soil-stored seed in a broad range of species in mediterranean-type systems. However, relatively little work has been conducted in south-eastern Australian heathlands. This study examined the effects of heat and smoked water on germination of the soil seed bank in a mature sand heathland within the Gippsland Lakes Coastal Park, in south-eastern Australia. Heat was clearly the most successful treatment for promoting seed germination, followed by smoked water, then controls, with 55% of species present in the germinable soil seed bank requiring a heat or smoke stimulus to promote seed germination. Mean species richness of the germinable soil seed bank was found to be significantly higher in heat-treated soil than in smoke and control treatments. Seedling density of heat-treated soil was almost 10 times that of controls, while smoke-treated soil was almost five times that of controls. Seedling emergence was fastest in heat-treated soil, followed by smoke and control soils. Of the species found in the soil seed bank, 25% were absent from the extant vegetation, suggesting the existence of post-fire colonisers in the soil seed bank. The results have implications for the design of soil seed bank experiments and the use of fire as a tool in vegetation management.
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Gray, Jonathan M., Greg A. Chapman e Brian W. Murphy. "Land management within capability: a new scheme to guide sustainable land management in New South Wales, Australia". Soil Research 53, n.º 6 (2015): 683. http://dx.doi.org/10.1071/sr14196.
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A new evaluation scheme, land management within capability (LMwC), used to guide sustainable land management in New South Wales (NSW), is presented. The scheme semi-quantitatively categorises the potential impacts of specific land-management actions and compares these with the inherent physical capability of the land in relation to a range of land-degradation hazards. This leads to the derivation of LMwC indices, which signify the sustainability of land-management practices at the scale of individual sites up to broader regions. The LMwC scheme can be used to identify lands at greatest risk from various land-degradation hazards. It can help to guide natural resource agencies at local, regional and state levels to target priorities and promote sustainable land management across their lands. Few other schemes that assess the sustainability of a given land-management regime in a semi-quantitative yet pragmatic manner are found in the literature. The scheme has particular application for regional soil-monitoring programs and it was applied in such a program over NSW in 2008–09. The results suggested that the hazards most poorly managed across the state are wind erosion, soil acidification and soil organic carbon decline. The LMwC scheme, or at least its underlying concepts, could be readily applied to other jurisdictions.
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Moxham, Claire, Josh Dorrough, Mick Bramwell e Brad J. Farmilo. "Fire exclusion and soil texture interact to influence temperate grassland flora in south-eastern Australia". Australian Journal of Botany 64, n.º 5 (2016): 417. http://dx.doi.org/10.1071/bt16056.
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Fire has a major influence on the structure and composition of temperate grasslands and woodlands. We investigated whether the impacts of fire exclusion on a temperate grassland plant community varied according to the scale of investigation and soil texture. Ten sites with known fire histories were selected along a soil texture gradient in south-eastern Australia. Floristics and ground layer attributes were investigated at small (0.25 m2) and large (100 m2) spatial scales in regularly burnt and unburnt grasslands. Fire exclusion over a 10 year period led to declines in native species diversity, richness and cover at both spatial scales and in most cases effects were consistent regardless of soil texture. However, the richness of native plant species at small scales and the cover of native plants at large scales were most negatively influenced by fire exclusion on fine textured soils. Conversely, at large scales, exotic plant richness and cover were only weakly increased by fire exclusion. Responses of eight common species were modelled and in seven of these, fire exclusion was a strong predictor of occurrence, although both positive and negative responses were observed. These results reiterate the importance of frequent fire as a management tool in temperate grasslands, but also shed light on how sites may require specific fire management regimes depending on the underlying soil texture.
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Walden, L. L., R. J. Harper, D. S. Mendham, D. J. Henry e J. B. Fontaine. "Eucalyptus reforestation induces soil water repellency". Soil Research 53, n.º 2 (2015): 168. http://dx.doi.org/10.1071/sr13339.
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There is an increasing interest in eucalypt reforestation for a range of purposes in Australia, including pulp-wood production, carbon mitigation and catchment water management. The impacts of this reforestation on soil water repellency have not been examined despite eucalypts often being associated with water repellency and water repellency having impacts on water movement across and within soils. To investigate the role of eucalypt reforestation on water repellency, and interactions with soil properties, we examined 31 sites across the south-west of Western Australia with paired plots differing only in present land use (pasture v. plantation). The incidence and severity of water repellency increased in the 5–8 years following reforestation with Eucalyptus globulus. Despite this difference in water repellency, there were no differences in soil characteristics, including soil organic carbon content or composition, between pasture and plantation soils, suggesting induction by small amounts of hydrophobic compounds from the trees. The incidence of soil water repellency was generally greater on sandy-surfaced (<10% clay content) soils; however, for these soils 72% of the pasture sites and 31% of the plantation were not water repellent, and this was independent of measured soil properties. Computer modelling revealed marked differences in the layering and packing of waxes on kaolinite and quartz surfaces, indicating the importance of interfacial interactions in the development of soil water repellency. The implications of increased water repellency for the management of eucalyptus plantations are considered.
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Sadras, Victor O., e John F. Angus. "Benchmarking water-use efficiency of rainfed wheat in dry environments". Australian Journal of Agricultural Research 57, n.º 8 (2006): 847. http://dx.doi.org/10.1071/ar05359.
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Attainable water-use efficiency relates attainable yield, i.e. the best yield achieved through skilful use of available technology, and seasonal evapotranspiration (ET). For wheat crops in south-eastern Australia, there is a common, often large gap between actual and attainable water-use efficiency. To evaluate whether this gap is only an Australian problem or a general feature of dry environments, we compared water-use efficiency of rainfed wheat in south-eastern Australia, the North American Great Plains, China Loess Plateau, and the Mediterranean Basin. A dataset of published data was compiled (n = 691); water-use efficiency (WUEY/ET) was calculated as the ratio between actual grain yield and seasonal ET. Maximum WUEY/ET was 22 kg grain/ha.mm. Average WUEY/ET (kg grain/ha.mm) was 9.9 for south-eastern Australia, 9.8 for the China Loess Plateau, 8.9 for the northern Great Plains of North America, 7.6 for the Mediterranean Basin, and 5.3 for the southern-central Great Plains; the variation in average WUEY/ET was largely accounted for by reference evapotranspiration around flowering. Despite substantial differences in important factors including soils, precipitation patterns, and management practices, crops in all these environments had similarly low average WUEY/ET, between 32 and 44% of attainable efficiency. We conclude that low water-use efficiency of Australian crops is not a local problem, but a widespread feature of dry environments. Yield gap analysis for crops in the Mallee region of Australia revealed low availability of phosphorus, late sowing, and subsoil chemical constraints as key factors reducing water-use efficiency, largely through their effects on soil evaporation.
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Condon, Jason, Helen Burns e Guangdi Li. "The extent, significance and amelioration of subsurface acidity in southern New South Wales, Australia". Soil Research 59, n.º 1 (2021): 1. http://dx.doi.org/10.1071/sr20079.
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Soil pH is seldom uniform with depth, rather it is stratified in layers. The soil surface (0–0.02 m) commonly exhibits relatively high pH and overlies a layer of acidic soil of 0.05–0.15 m deep, termed an acidic subsurface layer. Commercial and research sampling methods that rely on depth increments of 0.1 m either fail to detect or under report the presence or magnitude of pH stratification. The occurrence of pH stratification and the presence of acidic subsurface layers may cause the extent of acidity in NSW agricultural land to be underestimated. Though the cause of pH stratification in agricultural systems is well understood, the effect on agricultural production is poorly quantified due in part to inadequate sampling depth intervals resulting in poor identification of acidic subsurface layers. Although liming remains the best method to manage acidic soil, current practices of low pH targets (pHCa 5), inadequate application rates and no or ineffective incorporation have resulted in the continued formation of acidic subsurface layers. Regular monitoring in smaller depth increments (0.05 m), higher pH targets (pHCa > 5.5) and calculation of lime rate requirements that account for application method are required to slow or halt soil degradation by subsurface acidification. If higher pH is not maintained in the topsoil, the acidification of subsurface soils will extend further into the profile and require more expensive operations that mechanically place amendments deep in the soil. Although the use of organic amendments has shown promise to enhance soil acidity amelioration with depth, the longevity of their effect is questionable. Consequently, proactive, preventative management of topsoil pH with lime addition remains the most cost-effective solution for growers.
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Lattimore, MAE. "Pastures in temperate rice rotations of south-eastern Australia". Australian Journal of Experimental Agriculture 34, n.º 7 (1994): 959. http://dx.doi.org/10.1071/ea9940959.
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Legume-based pastures have long been an integral part of rice growing in the southern New South Wales irrigation areas and still offer potential to improve the productivity, profitability, and sustainability of the temperate rice-cropping system.This paper reviews both historical and current aspects of pastures in temperate rice rotations in southern New South Wales and highlights the importance of pastures in sustaining this cropping system as environmental pressures increase. Topics discussed include pasture species and rotations, their role in improving soil fertility and sustainability, the value of pastures in weed control, and their management for maximum profitability.
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Lamb, D. W. "The use of qualitative airborne multispectral imaging for managing agricultural crops - a case study in south-eastern Australia". Australian Journal of Experimental Agriculture 40, n.º 5 (2000): 725. http://dx.doi.org/10.1071/ea99086.
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Charles Sturt University has operated an airborne multispectral imaging system as a research support and management tool over south-eastern Australian crops since 1994. Our experiences have demonstrated the utility, timeliness and cost-effectiveness of qualitative multispectral imagery for monitoring and managing spatial variability in a range of agricultural crops, yet to date the technology remains underutilised in Australia. Images showing variations in the texture of soils in paddocks are a useful indicator of the location of different soil zones for soil sampling, and can assist in siting of treatment plots within paddocks. Multispectral imagery can be used for a synoptic assessment of early weed pressure in fallow paddocks or seedling crops. Locating variability in crop emergence and, later, canopy vigour and biomass, are all potentially means of undertaking precision farming without the capital investment associated with yield mapping. However, like any remote monitoring tool, follow-up ground-truthing must always be used to establish or confirm the causes of observed variability. The use of the technology as part of a greater data acquisition strategy is recommended.
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White, D. A., M. Battaglia, C. Macfarlane, D. Mummery, J. F. McGrath e C. L. Beadle. "Selecting species for recharge management in Mediterranean south western Australia – some ecophysiological considerations". Plant and Soil 257, n.º 2 (dezembro de 2003): 283–93. http://dx.doi.org/10.1023/a:1027338731384.
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Schoknecht, Noel. "Report card on sustainable natural-resource use in the agricultural regions of Western Australia". Soil Research 53, n.º 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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Badgery, Warwick B., Aaron T. Simmons, Brian M. Murphy, Andrew Rawson, Karl O. Andersson, Vanessa E. Lonergan e Remy van de Ven. "Relationship between environmental and land-use variables on soil carbon levels at the regional scale in central New South Wales, Australia". Soil Research 51, n.º 8 (2013): 645. http://dx.doi.org/10.1071/sr12358.
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The potential to change agricultural land use to increase soil carbon stocks has been proposed as a mechanism to offset greenhouse gas emissions. To estimate the potential carbon storage in the soil from regional surveys it is important to understand the influence of environmental variables (climate, soil type, and landscape) before land management can be assessed. A survey was done of 354 sites to determine soil organic carbon stock (SOC stock; Mg C/ha) across the Lachlan and Macquarie catchments of New South Wales, Australia. The influences of climate, soil physical and chemical properties, landscape position, and 10 years of land management information were assessed. The environmental variables described most of the regional variation compared with management. The strongest influence on SOC stock at 0–10 cm was from climatic variables, particularly 30-year average annual rainfall. At a soil depth of 20–30 cm, the proportion of silica (SiO2) determined by mid-infrared spectra (SiMIR) had a negative relationship with SOC stock, and sand and clay measured by particle size analysis also showed strong relationships at sites where measured. Of the difference in SOC stock explained by land use, cropping had lower soil carbon than pasture in rotation or permanent pasture at 0–10 cm. This relationship was consistent across a rainfall gradient, but once soil carbon was standardised per mm of average annual rainfall, there was a greater difference between cropping and permanent pasture with increasing SiMIR in soils. Land use is also regulated by climate, topography, and soil type, and the effect on SOC stock is better assessed in smaller land-management units to remove some variability due to climate and soil.
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Mathers, Nicole J., Zhihong Xu, Susan J. Berners-Price, M. C. Senake Perera e Paul G. Saffigna. "Hydrofluoric acid pre-treatment for improving 13C CPMAS NMR spectral quality of forest soils in south-east Queensland, Australia". Soil Research 40, n.º 4 (2002): 665. http://dx.doi.org/10.1071/sr01073.
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Hydrofluoric acid (HF) was used to pre-treat forest soils of south-east Queensland for assessing the effectiveness of iron (Fe) removal, carbon (C) composition using 13C cross-polarisation (CP) with magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) before and after the HF pre-treatment, and the improvement of 13C CPMAS NMR spectra. Soil samples were collected from 4 experimental sites of different soil types, harvest residue management or prescribed burning, and tree species. More than 86% of Fe was in all soil types removed by the HF treatment. The 13C NMR spectral quality was improved with increased resolution, especially in the alkyl C and O-alkyl C regions, and reduced NMR run-time (1-5�h per sample compared with >20�h per sample without the pre-treatment). The C composition appeared to alter slightly after the pre-treatment, but this might be largely due to improved spectrometer conditions and increased resolution leading to more accurate NMR spectral integration. Organic C recovery after HF pre-treatment varied with soil types and forest management, and soluble soil organic matter (SOM) could be lost during the pre-treatment. The Fourier Transform-Infrared (FT-IR) spectra of HF extracts indicated the preferential removal of carboxylic C groups during the pre-treatment, but this could also be due to adsorbed water on the mineral matter. The NMR spectra revealed some changes in C composition and quality due to residue management and decomposition. Overall, the HF treatment was a useful pre-treatment for obtaining semi-quantitative 13C CPMAS NMR spectra of subtropical Australian forest soils.
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Mendham, D. S., A. M. O'Connell e T. S. Grove. "Organic matter characteristics under native forest, long-term pasture, and recent conversion to Eucalyptus plantations in Western Australia: microbial biomass, soil respiration, and permanganate oxidation". Soil Research 40, n.º 5 (2002): 859. http://dx.doi.org/10.1071/sr01092.
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The influence of land-use management on Walkley-Black soil carbon (C) concentration, 3 concentrations of permanganate oxidisable C (33, 167, and 333 mm), microbial biomass, and soil respiration in a laboratory incubation was tested in surface soil from 10 sites in south-western Australia. The sites ranged in total C concentration from 1.9 to 8.3%, and represented a broad climatic and soil-type distribution across south-western Australia. At each of the sites, 0-10 cm soil was collected from plots in pasture (20-71 years old), Eucalyptus globulus plantation (7-10 years old, established on ex-pasture), and native vegetation. Soil profiles and position in the landscape for each of the land-use types were matched as closely as possible at each site to minimise influences other than land use. Total C was highly correlated with clay content. Land use caused no significant change in the relationship between total C and soil texture, and land use had little effect on total C concentration. Permanganate-oxidisable C was highly correlated with Walkley-Black organic C (R2�>�0.90) for all 3 concentrations that were investigated. Only the most dilute concentration of permanganate-oxidisable C (33 mm) was sensitive enough to detect small changes in soil organic matter with land use (P = 0.045). Microbial biomass and respiration at 25 kPa matric potential moisture content and 35°C temperature were used as biological indicators of soil organic matter lability. Cumulative respired C was more sensitive to land use than Walkley-Black organic C, with lower respiration in native soils compared with managed soils with low C concentrations, but higher than the managed soils at sites with high C concentrations. Microbial biomass was not significantly affected by land use. Microbial biomass and cumulative respired C were strongly influenced by soil texture, with the microbial quotient (proportion of microbial biomass in total carbon) and the proportion of total C respired significantly lower in soils with higher silt and clay contents. Land use had no significant effect on these relationships. Overall, land use caused only minor differences in the biological and chemical indicators of organic matter quality across a broad range of sites in south-western Australia.
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Orgill, S. E., C. M. Waters, G. Melville, I. Toole, Y. Alemseged e W. Smith. "Sensitivity of soil organic carbon to grazing management in the semi-arid rangelands of south-eastern Australia". Rangeland Journal 39, n.º 2 (2017): 153. http://dx.doi.org/10.1071/rj16020.
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This study compared the effects of grazing management on soil organic carbon (OC) stocks in the semi-arid rangelands of New South Wales, Australia. A field survey was conducted at three locations (Brewarrina, Cobar–North and Cobar–South), with paired sites of long-term (>8 years) rotational grazing management and continuously grazed pastures (either set stocked or no stocking). At each location, soil OC, carbon (C) fractions, soil nitrogen (N) and microsite and site factors (including ground cover and woody vegetation) were measured. The control of total grazing pressure (TGP) through rotational grazing and exclusion fencing did not increase soil C stocks compared with continuous grazing for the majority of comparisons. However, in some parts of the landscape, higher soil C stock was found with TGP control, for example on the ridges (21.6 vs 13.3 t C ha–1 to 0.3 m). C stocks increased with litter and perennial ground cover and with close proximity to trees. At Brewarrina, C stocks were positively affected by perennial plant cover (P < 0.001) and litter (P < 0.05), whereas at Cobar–North and Cobar–South C stocks were positively affected by the presence of trees (P < 0.001), with higher C stocks in close proximity to trees, and with increasing litter cover (P < 0.01). The present study demonstrates that natural resource benefits, such as increased perennial cover, can be achieved through controlling TGP in the rangelands but increases in soil C may be limited in certain parts of the landscape. These findings also highlight that interactions between managed and unmanaged TGP and microsite factors, such as ground cover and proximity to woody vegetation, need to be considered when evaluating the role of changed grazing management on soil C.
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Fillery, IR, e KJ McInnes. "Components of the fertiliser nitrogen balance for wheat production on duplex soils". Australian Journal of Experimental Agriculture 32, n.º 7 (1992): 887. http://dx.doi.org/10.1071/ea9920887.
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In this paper, we review literature on the fate of fertiliser nitrogen (N) applied to duplex soils in wheat-growing regions of southern Australia, and discuss the contribution of specific N transformations to N loss. Duplex soils are characterised by the presence of soil material, within the rooting depth of crops, that possess hydraulic conductivities that are lower than those of overlying material. Denitrification and the transport of nitrate below rooting depth of crops are thought to be the chief causes of loss of fertiliser N and to contribute to poor grain yields. Ammonia volatilisation could contribute also to N loss. The fate of fertiliser N commonly applied to wheat in southern Australia has largely been evaluated using budgeting procedures using l5N, a stable isotope of N. Results from studies in south-eastem Australia, using red-brown earths, indicate that between 10 and 40% of applied 15N can be lost irrespective of time of application to wheat. Denitrification is believed to be the chief cause of loss of l5N. Similar studies on yellow duplex soils in Western Australia have shown fertiliser N loss to range from 70% to no loss of the l5N applied. The exact cause of N loss in Western Australian studies is unclear. There was circumstantial evidence for ammonia loss from surface-applied urea, and evidence of leaching of nitrates from this and other ammoniumbased fertilisers. The role of denitrification has not been clarified in Western Australian studies. In the majority of studies, recovery of 15N in aboveground biomass exceeded 40% of that applied. In addition, between 17 and 48% of applied 15N, of which 10-15% may be in root material, has been recovered in the soil organic matter pool. The predominance of the denitrification process in south-eastern Australian soils, and the inability to improve the efficiency of utilisation of 15N by delaying the time of application to wheat underscores the importance of controlling the nitrification process using inhibitors. Management options for Western Australian soils are less clear. Some agronomic experiments have demonstrated the advantage of delaying the application of fertiliser N to wheat to improve the efficiency of its utilisation. There is also evidence which suggests that N should be applied early in the growth cycle to promote tiller development and thereby increase the potential for grain yield.
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Xiong, X., F. Stagnitti, G. Allinson, N. Turoczy, P. Li, M. LeBlanc, M. A. Cann et al. "Effects of clay amendment on adsorption and desorption of copper in water repellent soils". Soil Research 43, n.º 3 (2005): 397. http://dx.doi.org/10.1071/sr04088.
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Copper is an important micronutrient and trace amounts are essential for crop growth. However, high concentrations of copper will produce toxic effects. Australia is increasingly developing production of crops in water repellent soils. Clay amendment, a common amelioration techniques used in Australia, has demonstrated agronomic benefits in increased crop or pasture production. The sorption and desorption of copper and the effect of clay treatment on copper behaviour in a water repellent soil collected from an experimental farm in South Australia is studied. We found that the water repellent soils amended with clay have an increased adsorption capacity of copper. Also the clay-amended soils had an increased ratio of specific sorption to total sorption of copper. The implications of this study to the sustainable agro-environmental management of water repellent soils is discussed.
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Evans, J. "An evaluation of potential Rhizobium inoculant strains used for pulse production in acidic soils of south-east Australia". Australian Journal of Experimental Agriculture 45, n.º 3 (2005): 257. http://dx.doi.org/10.1071/ea03129.
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Profitability of the pulse industry relies considerably on crop nitrogen fixation because this process supplies greater than 60% of pulse crop nitrogen. Therefore the industry requires the most efficient Rhizobium symbioses and effective inoculation management. Re-appraisal of the recommended inoculant strain for field pea, SU303, in south-east Australia, was warranted by field evidence that SU303 failed to maximise grain yield at sites in Western Australia. Re-appraisal of the inoculant strain for faba bean and lentil, WSM1274, was warranted because of anecdotal evidence from Western Australia of associated crop failures. In addition, a glasshouse study in Western Australia reported greater dry matter production by faba bean and lentil inoculated with strains other than WSM1274. This paper reports trials comparing potential inoculant strains for field pea and faba bean in soils of south-east Australia. Comparisons are based on efficiency for nitrogen fixation, survival on seed and survival in soil. Additionally, because the pulse industry lacked comprehensive information to assist decision making on the need for recurring inoculation, relevant investigation of this issue is also reported. The results of 3 field experiments for efficiency for nitrogen fixation, over mildly (pHCa 5.0) to strongly (pHCa 4.3) acidic soil in south-east Australia supported replacing SU303 as the commercial inoculant. The efficiency for nitrogen fixation of WSM1274 on faba bean was not found to be inferior to alternative strains. However, its capacity for survival on seed at temperatures of 15°C and above, over a wide range of relative humidity, and perhaps its capacity for survival in acidic soil, was inferior. This provided additional evidence to justify the replacement of this inoculant strain that was agreed to by a national steering committee in 2001, based on the Western Australia reports, the early experiments in this study and those of a collaborative study in Victoria. Alternative inoculant strains to SU303 and WSM1274 were identified in the current study. Temperature and relative humidity conditions suitable for maintaining inoculant viability with extended storage of inoculated field pea and faba bean are also discussed. A survey of rhizobia surviving in soil was used to determine the time scale of persistence of Rhizobium leguminosarum bv. viciae and Bradyrhizobium sp. (Lupinus) in soils of the south-east. It was concluded that in soils of pH (CaCl2) <5.1, inoculation of field pea and faba bean should be routinely practiced; none of the strains of R. leguminosarum bv. viciae tested showed ability for survival in strongly acidic soil sufficient to obviate seed inoculation. It was further concluded that the absence of a legume host for lupin rhizobia for 4 or more years would also warrant reintroducing inoculant of B. sp. (Lupinus).
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Angus, J. F., R. R. Gault, M. B. Peoples, M. Stapper e A. F. van Herwaarden. "Soil water extraction by dryland crops, annual pastures, and lucerne in south-eastern Australia". Australian Journal of Agricultural Research 52, n.º 2 (2001): 183. http://dx.doi.org/10.1071/ar00103.
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The extraction of soil water by dryland crops and pastures in south-eastern Australia was examined in 3 studies. The first was a review of 13 published measurements of soil water-use under wheat at several locations in southern New South Wales. Of these, 8 showed significantly more water extracted by crops managed with increased nitrogen supply or growing after a break crop. The mean additional soil water extraction in response to break crops was 31 mm and to additional N was 11 mm. The second study used the SIMTAG model to simulate growth and water-use by wheat in relation to crop management at Wagga Wagga. The model was set up to simulate crops that produced either average district yields or the potential yields achievable with good management. When simulated over 50 years of weather data, the combined water loss as drainage and runoff was predicted to be 67 mm/year for poorly managed crops and 37 mm for well-managed crops. Water outflow was concentrated in 70% of years for the poorly managed crops and 56% for the well-managed crops. In those years the mean losses were estimated to be 95 mm and 66 mm, respectively. The third study reports soil water measured twice each year during a phased pasture–crop sequence over 6.5 years at Junee. Mean water content of the top 2.0 m of soil under a lucerne pasture averaged 211 mm less than under a subterranean clover-based annual pasture and 101 mm less than under well-managed crops. Collectively, these results suggest that lucerne pastures and improved crop management can result in greater use of rainfall than the previous farming systems based on annual pastures, fallows, and poorly managed crops. The tactical use of lucerne-based pastures in sequence with well-managed crops can help the dewatering of the soil andreduce or eliminate the risk of groundwater recharge.
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Stevens, D. P., M. J. McLaughlin e M. K. Smart. "Effects of long-term irrigation with reclaimed water on soils of the Northern Adelaide Plains, South Australia". Soil Research 41, n.º 5 (2003): 933. http://dx.doi.org/10.1071/sr02049.
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On a small scale, reclaimed water (RCW) use has been practised on the Northern Adelaide Plains (NAP) horticultural districts for more than 28 years. The RCW has had approximately 1.7 times the salinity and twice the sodium absorption ratio (SAR) of bore water commonly used for irrigation in the district. Recently, a large-scale reclamation scheme has been commissioned which could eventually supply approximately 30 GL of RCW to over 250 growers on the NAP. This study compared historical water quality and time of use data with physico-chemical properties of soil cores taken from sites where reclaimed (RCW-irrigated) or bore water had been used for irrigation, or sites that had not been irrigated (virgin). The aim was to determine if current farming practices irrigating with RCW could, now or in the future, lead to a decrease in yields through detrimental increases in soil salinity, sodicity, and boron (B) concentrations, and to determine if these changes were significantly different from bore-irrigated or virgin sites. Data suggested that changes in soil salinity and B concentration from RCW use would not decrease yields. However, changes in soil SAR had the potential to restrict drainage and consequently increase salinity; although a more functional critical SAR value for the NAP soils needs to be defined to assess this potential. These findings suggest that farming methods, in the 1967–95 period, did not address the physico-chemical changes associated with the use of more sodic RCW. Considering the future scale of RCW use, the SAR of the irrigation water may need to be decreased and/or appropriate farming methods developed and practised with the use of RCW to protect these soils for future horticultural activities. A low cost soil test, using a simple 1 : 5 soil : water extract was compared with accepted soil extracts (for assessing detrimental physico-chemical soil changes) and is proposed as a grower management tool to assist in monitoring the physico-chemical changes of the NAP soils.
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Pereg, Lily L. "Black root rot of cotton in Australia: the host, the pathogen and disease management". Crop and Pasture Science 64, n.º 12 (2013): 1112. http://dx.doi.org/10.1071/cp13231.
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Black root rot is a seedling disease caused by the soil-borne fungal pathogen Thielaviopsis basicola, a species with a worldwide distribution. Diseased plants show blackening of the roots and a reduced number of lateral roots, stunted or slow growth, and delayed flowering or maturity. It was first detected in cotton in Australia in 1989, and by 2004, T. basicola reached all cotton-growing regions in New South Wales and Queensland and the disease was declared as an Australian pandemic. This review covers aspects of the disease that have implications in black root rot spread, severity and management, including the biology and ecology of T. basicola, host range and specificity, chemical and biological control of T. basicola in cotton cropping systems, and crop rotations and host resistance. This review is of special interest to Australian readers; however, the incorporation of ample information on the biology of the pathogen, its interactions with plants and it relation to disease management will benefit readers worldwide.
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Wilson, AD, NA Abraham, R. Barratt, J. Choate, DR Green, RJ Harland, RE Oxley e RJ Stanley. "Evaluation of methods of assessing vegetation change in the semi-arid rangelands of southern Australia." Rangeland Journal 9, n.º 1 (1987): 5. http://dx.doi.org/10.1071/rj9870005.
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Methods for measuring long-term changes in vegetation and soil condition were evaluated in terms of recording error, efficiency and value in meeting management objectives. The evaluation was made on 4-5 sites for each of six vegetation types across the semi-arid rangelands of South Australia and New South Wales. In the semi-arid woodlands the lowest errors of measurement (C.V. = 12-14%) were associated with point measures of canopy cover, while in the chenopod shrublands the most precise measure in most situations was the density of shrub clumps (C.V. = 12-16%). Measures of herbaceous and litter cover had a high error of measurement (e.g. C.V. = 60%) and observers were significantly different. The point measurement of the area of degraded soil surface was reliable on duplex soils, but not on gradational soils. The results are discussed in terms of their application for the monitoring of change in range condition. It is concluded that the most appropriate measure of the shrub layer is foliar cover in woodlands and clump density in chenopod shrublands.
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Bell, M., N. Seymour, G. R. Stirling, A. M. Stirling, L. Van Zwieten, T. Vancov, G. Sutton e P. Moody. "Impacts of management on soil biota in Vertosols supporting the broadacre grains industry in northern Australia". Soil Research 44, n.º 4 (2006): 433. http://dx.doi.org/10.1071/sr05137.
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The grain-producing regions of northern New South Wales and southern and central Queensland are characterised by cropping systems that are strongly dependent on stored soil moisture rather than in-crop rainfall, and tillage systems that are increasingly reliant on zero or minimum tillage. Crops are grown relatively infrequently and crop rotations are dominated by winter and summer grains (wheat [Triticum aestivum L.] and sorghum [Sorghum bicolor L. Moench], respectively), with smaller areas of grain legumes and cotton (Gossypium hirsutum L.). The grey, black, and brown Vertosols represent the more productive soils in the region under rainfed cropping, and are the focus of work reported in this study. Soil samples were collected from surface soils (0–0.30 m) across the region, utilising sites of long term tillage and residue management studies, fertiliser trials, and commercial fields to enable an assessment of the impact of various management practices on soil biological properties. A number of biological and biochemical parameters were measured (microbial biomass C, total organic C and labile C fractions, total C and N, microbial activity using FDA, cellulase activity, free living nematodes, total DNA and fatty acid profiles), and the response of wheat, sorghum, and chickpea (Cicer arietinum L.) to steam pasteurisation was assessed in glasshouse bioassays. The objective was to obtain an indication of the biological status of grain-growing soils and assess the impact of biological constraints in soils from different regions and management systems. Results showed that biological activity in cropped soils was consistently low relative to other land uses in northern Australia, with management practices like stubble retention and adoption of zero tillage producing relatively small benefits. In the case of zero tillage, many of these benefits were confined to the top 0.05 m of the soil profile. Fallowing to recharge soil moisture reserves significantly reduced all soil biological parameters, while pasture leys produced consistent positive benefits. Breaking a long fallow with a short duration grain or brown manure crop significantly moderated the negative effects of a long bare fallow on soil biology. Use of inorganic N and P fertilisers produced minimal effects on soil biota, with the exception of one component of the free-living nematode community (the Dorylaimida). The glasshouse bioassays provided consistent evidence that soil biota were constraining growth of both grain crops (sorghum and wheat) but not the grain legume (chickpea). The biota associated with this constraint have not yet been identified, but effects were consistent across the region and were not associated with the presence of any known pathogen or correlated with any of the measured soil biological or biochemical properties. Further work to confirm the existence and significance of these constraints under field conditions is needed. None of the measured biological or biochemical parameters consistently changed in response to management practices, while conflicting conclusions could sometimes be drawn from different measurements on the same soil sample. This highlights the need for further work on diagnostic tools to quantify soil biological communities, and suggests there is no clear link between measured changes in soil biological communities and economically or ecologically important soil attributes.
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Thomas, M., R. W. Fitzpatrick e G. S. Heinson. "An expert system to predict intricate saline - sodic subsoil patterns in upland South Australia". Soil Research 47, n.º 6 (2009): 602. http://dx.doi.org/10.1071/sr08244.
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Digital soil mapping (DSM) offers apparent benefits over more labour-intensive and costly traditional soil survey. Large cartographic scale (e.g. 1 : 10 000 scale) soil maps are rare in Australia, especially in agricultural areas where they are needed to support detailed land evaluation and targeted land management decisions. We describe a DSM expert system using environmental correlation that applies a priori knowledge from a key area (128 ha) soil–landscape with a regionally repeating toposequence to predict the distribution of saline–sodic subsoil patterns in the surrounding upland farming region (2275 ha) in South Australia. Our predictive framework comprises interrelated and iterative steps, including: (i) consolidating a priori knowledge of the key area soil–landscape; (ii) refining existing mentally held and graphic soil–landscape models; (iii) selecting suitable environmental covariates compatible with geographic information systems (GIS) by interrogation via 3D visualisation using a GIS; (iv) transforming the existing soil–landscape models to a computer model; (v) applying the computer model to the environmental variables using the expert system; (vi) performing the predictive mapping; and (vii) validation. The environmental covariates selected include: digital terrain attributes of slope gradient, topographic wetness index and plan curvature, and airborne gamma-radiometric K%. We apply selected soil profile physiochemical data from a prior soil survey to validate mapping. Results showed that we correctly predicted the saline–sodic subsoils in 10 of 11 reference profiles in the region.