Artículos de revistas: "Soil structure South Australia"

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Gardner, WK, RG Fawcett, GR Steed, JE Pratley, DM Whitfield, Hvan Rees y Rees H. Van. "Crop production on duplex soils in south-eastern Australia". Australian Journal of Experimental Agriculture 32, n.º 7 (1992): 915. http://dx.doi.org/10.1071/ea9920915.

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The environment, duplex soil types and trends in crop production in South Australia, southern New South Wales, north-eastern and north-central Victoria, the southern Wimmera and the Victorian Western District are reviewed. In the latter 2 regions, pastoral industries dominate and crop production is curtailed by regular and severe soil waterlogging, except for limited areas of lower rainfall. Subsurface drainage can eliminate waterlogging, but is feasible only for the Western District where subsoils are sufficiently stable. The other regions all have a long history of soil degradation due to cropping practices, but these effects can now be minimised with the use of direct drilling and stubble retention cropping methods. A vigorous pasture ley phase is still considered necessary to maintain nitrogen levels and to restore soil structure to adequate levels for sustainable farming. Future productivity improvements will require increased root growth in the subsoils. Deep ripping, 'slotting' of gypsum, and crop species capable of opening up subsoils are techniques which may hold promise in this regard. The inclusion of lucerne, a perennial species, in annual pastures and intercropping at intervals is a technique being pioneered in north-central and western Victoria and may provide the best opportunity to crop duplex soils successfully without associated land degradation.

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Doran-Browne, Natalie A., John Ive, Phillip Graham y 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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3

Dolling, P. J., R. A. Latta, P. R. Ward, M. J. Robertson y S. Asseng. "Soil water extraction and biomass production by lucerne in the south of Western Australia". Australian Journal of Agricultural Research 56, n.º 4 (2005): 389. http://dx.doi.org/10.1071/ar04158.

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To understand the factors involved in lucerne reducing drainage below the root-zone and influencing lucerne biomass production and water extraction were analysed in the south of Western Australia. The lucerne was grown for 3 years before removal. The factors investigated as part of the water extraction analysis included the rate of advance of the extraction front or extraction front velocity (EFV, mm/day), the soil plant-available water-holding capacity (PAWC, mm/m soil), and the temporal change in soil water deficit (drainage buffer, mm). The drainage buffer is related to the EFV and PAWC. A site with deep sand had the highest EFV (mean of 9.2 mm/day) but the lowest PAWC (mean of 32 mm/m soil) to a depth of 4 m. In the duplex soils the EFV was 18–34% of the deep sand EFV and the PAWC was 60–222% higher than the deep sand PAWC to a depth of 1.6–2.1 m. The EFV was reduced by the higher clay content and sodicity in the B horizon of the duplex soils. The highest drainage buffer measurements occurred in the deep sand site and the better structured duplex soils and therefore these soils will have the greater effect on reducing drainage below the root-zone. However, lucerne was able to create a drainage buffer to at least a depth of 1.5 m over 3 years and therefore contribute to a reduced drainage even on the most sodic and saline sites. Low soil pH did not affect the drainage buffer as much as soil texture and structure. Variation in biomass production of lucerne-based pastures was positively related to rainfall and water use (taking into account soil water storage and drainage losses) across sites, explaining approximately 50% of the biomass variation. Rainfall and water use could therefore be used for predicting lucerne biomass production in Western Australia. Biomass water use efficiency was highest in spring (15 kg/ha.mm) and least during autumn (4.5 kg/ha.mm).

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Banu, Nargis A., Balwant Singh y Les Copeland. "Microbial biomass and microbial biodiversity in some soils from New South Wales, Australia". Soil Research 42, n.º 7 (2004): 777. http://dx.doi.org/10.1071/sr03132.

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Eight surface soils (0–15 cm) including 1 Ferrosol, 2 Tenosols, 2 Kurosols, 1 Sodosol, 1 Chromosol, and 1 Kandosol were collected from mainly pasture sites in New South Wales. The soils had different physico-chemical properties and there were some differences between the sites in climatic conditions. Soil microbial biomass carbon (MBC) was estimated by the chloroform-fumigation extraction method, and substrate utilisation patterns determined by the Biolog method were used to assess the amount, functional diversity, substrate richness and evenness, and community structure of the microorganisms in these soils. The amount of MBC (585 µg C/g) and the microbial diversity (H´ = 3.24) were high in soils that had high clay (33%), organic C (5.96%), total N (0.45%), free iron (7.06%), moisture content (50%), and cation exchange capacitiy (133.5 mmolc/kg). These soil properties, e.g. soil moisture (r2 = 0.72), organic C (r2 = 0.58), total N (r2 = 0.63), free iron (r2 = 0.44), and EC (r2 = 0.53), were positively correlated with MBC and microbial diversity index, whereas pH and sand and silt content showed negative correlations. The climatic factors (temperature and rainfall) had no significant influence on either MBC or diversity.

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5

Yang, Xihua, Jonathan Gray, Greg Chapman, Qinggaozi Zhu, Mitch Tulau y Sally McInnes-Clarke. "Digital mapping of soil erodibility for water erosion in New South Wales, Australia". Soil Research 56, n.º 2 (2018): 158. http://dx.doi.org/10.1071/sr17058.

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Soil erodibility represents the soil’s response to rainfall and run-off erosivity and is related to soil properties such as organic matter content, texture, structure, permeability and aggregate stability. Soil erodibility is an important factor in soil erosion modelling, such as the Revised Universal Soil Loss Equation (RUSLE), in which it is represented by the soil erodibility factor (K-factor). However, determination of soil erodibility at larger spatial scales is often problematic because of the lack of spatial data on soil properties and field measurements for model validation. Recently, a major national project has resulted in the release of digital soil maps (DSMs) for a wide range of key soil properties over the entire Australian continent at approximately 90-m spatial resolution. In the present study we used the DSMs and New South Wales (NSW) Soil and Land Information System to map and validate soil erodibility for soil depths up to 100 cm. We assessed eight empirical methods or existing maps on erodibility estimation and produced a harmonised high-resolution soil erodibility map for the entire state of NSW with improvements based on studies in NSW. The modelled erodibility values were compared with those from field measurements at soil plots for NSW soils and revealed good agreement. The erodibility map shows similar patterns as that of the parent material lithology classes, but no obvious trend with any single soil property. Most of the modelled erodibility values range from 0.02 to 0.07 t ha h ha–1 MJ–1 mm–1 with a mean (± s.d.) of 0.035 ± 0.007 t ha h ha–1 MJ–1 mm–1. The validated K-factor map was further used along with other RUSLE factors to assess soil loss across NSW for preventing and managing soil erosion.

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6

Dolling, P. J., R. A. Latta, P. R. Ward, M. J. Robertson y S. Asseng. "Corrigendum to: Soil water extraction and biomass production by lucerne in the south of Western Australia". Australian Journal of Agricultural Research 56, n.º 9 (2005): 1010. http://dx.doi.org/10.1071/ar04158_co.

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To understand the factors involved in lucerne reducing drainage below the root-zone and influencing lucerne biomass production and water extraction were analysed in the south of Western Australia. The lucerne was grown for 3 years before removal. The factors investigated as part of the water extraction analysis included the rate of advance of the extraction front or extraction front velocity (EFV, mm/day), the soil plant-available water-holding capacity (PAWC, mm/m soil), and the temporal change in soil water deficit (drainage buffer, mm). The drainage buffer is related to the EFV and PAWC. A site with deep sand had the highest EFV (mean of 9.2�mm/day) but the lowest PAWC (mean of 32�mm/m soil) to a depth of 4�m. In the duplex soils the EFV was 18.34% of the deep sand EFV and the PAWC was 60.222% higher than the deep sand PAWC to a depth of 1.6.2.1�m. The EFV was reduced by the higher clay content and sodicity in the B horizon of the duplex soils. The highest drainage buffer measurements occurred in the deep sand site and the better structured duplex soils and therefore these soils will have the greater effect on reducing drainage below the root-zone. However, lucerne was able to create a drainage buffer to at least a depth of 1.5�m over 3 years and therefore contribute to a reduced drainage even on the most sodic and saline sites. Low soil pH did not affect the drainage buffer as much as soil texture and structure. Variation in biomass production of lucerne-based pastures was positively related to rainfall and water use (taking into account soil water storage and drainage losses) across sites, explaining approximately 50% of the biomass variation. Rainfall and water use could therefore be used for predicting lucerne biomass production in Western Australia. Biomass water use efficiency was highest in spring (15 kg/ha.mm) and least during autumn (4.5 kg/ha.mm).

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7

Cox, J. W., C. A. Kirkby, D. J. Chittleborough, L. J. Smythe y 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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Moxham, Claire, Josh Dorrough, Mick Bramwell y 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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9

Brandle, R. y K. E. Moseby. "Comparative ecology of two populations of Pseudomys australis in northern South Australia". Wildlife Research 26, n.º 4 (1999): 541. http://dx.doi.org/10.1071/wr97049.

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Two disparate populations of Pseudomys australis, in the southern and north-western Lake Eyre Basin of South Australia, were studied over a 3-year period using trapping and radio-tracking techniques. Various aspects of the species’ ecology were investigated. Past records of the species were almost always associated with population irruptions following exceptionally wet years. Aspects of population dynamics, fine-scale habitat use, activity ranges and burrows were studied and related to habitat condition during three dry seasons following a good season. Both areas were associated with floodout plains in a gibber desert environment but differed in soils and vegetation structure. The population dynamics and structure and home-range activity also differed. These differences appeared to relate to the availability and distribution of food and shelter in the respective locations. The differences between populations in the two areas are discussed with reference to the source/sink and refugia concepts.

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10

Kelly, B., C. Allan y 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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11

Thompson, Wendy A., David J. Eldridge y Stephen P. Bonser. "Structure of biological soil crust communities in Callitris glaucophylla woodlands of New South Wales, Australia". Journal of Vegetation Science 17, n.º 3 (2006): 271. http://dx.doi.org/10.1658/1100-9233(2006)017[0271:sobscc]2.0.co;2.

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12

Thompson, Wendy A., David J. Eldridge y Stephen P. Bonser. "Structure of biological soil crust communities in Callitris glaucophylla woodlands of New South Wales, Australia". Journal of Vegetation Science 17, n.º 3 (24 de febrero de 2006): 271–80. http://dx.doi.org/10.1111/j.1654-1103.2006.tb02446.x.

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13

Chan, K. Y., C. G. Dorahy, S. Tyler, A. T. Wells, P. P. Milham y I. Barchia. "Phosphorus accumulation and other changes in soil properties as a consequence of vegetable production, Sydney region, Australia". Soil Research 45, n.º 2 (2007): 139. http://dx.doi.org/10.1071/sr06087.

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A survey of 34 farms covering the major soil types used for growing vegetables within the greater Sydney metropolitan region (New South Wales, Australia) was undertaken to determine the effect of vegetable production on soil chemical and physical properties. Comparison of farmed ‘vegetable’ v. unfarmed ‘reference’ sites revealed that the soils used for vegetable production had extremely high concentrations of total P, Colwell-P, and CaCl2-extractable P (mean 1205, 224, and 4.3 mg/kg in the 0–0.30 m layer, respectively). In the 0–0.30 m soil layer, mean bicarbonate-extractable P (Colwell-P) concentrations have increased to up to 44 times that of the unfarmed reference soils and exceed that required for adequate vegetable nutrition. Concentrations of P in the soil solution (CaCl2-P) were up to 230 times that of the unfarmed reference soils. Moreover, the vegetable soils had low total soil carbon concentrations (mean 14.1 g/kg in the 0–0.10 m layer, only 57% of the mean concentration of the reference soils). These soils exhibited extremely low structural stability, which is likely to reduce soil infiltration rates and increase the potential for runoff. Marked changes in soil pH, EC, and exchangeable cations (Ca, Mg, and K) were also observed as a consequence of vegetable production. All of these changes are a consequence of current management practices used in vegetable production, which include application of high rates of inorganic fertilisers and poultry manure, as well as excessive cultivation. Excessive accumulation of P, to at least 0.30 m depth, coupled with a loss of soil structural stability, is of particular environmental concern. Options such as adopting minimum tillage, in conjunction with using alternative inputs such as low P composts and cover crops, as a means of improving soil structure and reducing the extent of P accumulation in these soils require further investigation.

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14

Phillips, SE, AR Milnes y RC Foster. "Calcified filaments - an example of biological influences in the formation of calcrete in South Australia". Soil Research 25, n.º 4 (1987): 405. http://dx.doi.org/10.1071/sr9870405.

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Scanning electron microscope (SEM) studies of calcareous soils and calcretes from South Australia reveal a fossilized community of soil micro-organisms dominated by filamentous structures preserved in fine detail by calcite. In the various calcrete lithological facies, the filaments form dense mats within channels and voids, and also occur within the matrix where they are intimately associated with micrite. The calcite forming the filaments has a variety of crystal habits: the nature of the microcrystals is specific to each filament but varies significantly between adjacent filaments. In the calcareous soils there are various stages between the primary filaments and the calcite encrusted structures characteristic of the calcretes, suggesting that in vivo biochemical processes dominate the mechanisms of calcification. This hypothesis is supported by the specificity of the habit of calcite microcrystals on each filament. It is suggested that the organisms deposit calcite microcrystals within the mucilaginous sheath or in the cell wall (or both) as a detoxification mechanism in response to their highly calcareous environment. Based on the identification of structures resembling fruiting bodies, at least some of the filaments appear to have been fungal hyphae, which are known to be responsible for stabilizing macroaggregates in soils. Calcified filaments may produce permanently stabilized macroaggregates which provide the locus for further carbonate precipitation, leading to eventual induration of the soil.

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15

Plescia, J. B., E. M. Shoemaker y C. S. Shoemaker. "Gravity survey of the Mount Toondina impact structure, South Australia". Journal of Geophysical Research 99, E6 (1994): 13167. http://dx.doi.org/10.1029/94je00660.

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16

Karim, Md Rajibul, Md Mizanur Rahman, Khoi Nguyen, Donald Cameron, Asif Iqbal y Isaac Ahenkorah. "Changes in Thornthwaite Moisture Index and Reactive Soil Movements under Current and Future Climate Scenarios—A Case Study". Energies 14, n.º 20 (17 de octubre de 2021): 6760. http://dx.doi.org/10.3390/en14206760.

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Expansive soils go through significant volume changes due to seasonal moisture variations resulting in ground movements. The ground movement related problems are likely to worsen in the future due to climate change. It is important to understand and incorporate likely future changes in design to ensure the resilience of structures built on such soils. However, there has been a limited amount of work quantifying the effect of climate change on expansive soils movement and related behaviour of structures. The Thornthwaite Moisture Index (TMI) is one of the commonly used climate classifiers in quantifying the effect of atmospheric boundary on soil behaviour. Using the long-term weather data and predicted future changes under different emission scenarios, a series of TMI maps are developed for South Australia. Potential changes in ground movement are then estimated for a selected area using a simplified methodology where the effect of future climate is captured through changes in TMI. Results indicate that South Australia is likely to face a significant reduction in TMI under all emission scenarios considered in this study. The changes in TMI will lead to a considerable increase in potential ground movement which will influence the behaviour of structures built on them and in some areas may lead to premature failure if not considered in the design.

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17

Brockwell, J., Catherine M. Evans, Alison M. Bowman y Alison McInnes. "Distribution, frequency of occurrence and symbiotic properties of the Australian native legume Trigonella suavissima Lindl. and its associated root-nodule bacteria". Rangeland Journal 32, n.º 4 (2010): 395. http://dx.doi.org/10.1071/rj09080.

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Trigonella suavissima Lindl. is an Australian native legume belonging to the tribe Trifolieae. It is an ephemeral species that is widely distributed in the arid interior of the continent where it occurs, following periodic inundation, on clay soils of the watercourse country of the Channel Country (far-western Queensland, north-east South Australia and north-western New South Wales). T. suavissima is the only member of its tribe that is endemic to Australia. Likewise, its root-nodule bacteria (Sinorhizobium sp.) may be the only member of its taxonomic group (S. meliloti, S. medicae) that is an Australian native. The distribution and frequency of occurrence of T. suavissima and the size of soil populations (density) of Sinorhizobium were monitored at 64 locations along inland river systems of the Channel Country. Measurements were made of (i) the nitrogen-fixing effectiveness of the symbioses between T. suavissima and strains of its homologous Sinorhizobium and (ii) the nitrogen-fixing effectiveness of the symbioses between legumes symbiotically related to T. suavissima and diverse strains of Sinorhizobium. It was concluded that the distribution and frequency of occurrence of T. suavissima is soil related. The species is most widespread on fine-textured clay soils with deep, self-mulching surfaces and high moisture-holding capacity. By contrast, the occurrence of T. suavissima is sporadic in the upper reaches of the inland river systems where the soils are poorly structured clays with lower moisture-holding capacity. Sinorhizobium is most abundant where the plant is most common. The nitrogen-fixing symbioses between T. suavissima and strains of Sinorhizobium isolated from soils across the region were consistently effective and often highly effective. Some of these strains fixed a little nitrogen with lucerne (Medicago sativa L.). T. suavissima also had some symbiotic (nitrogen-fixing) affinity with an exotic Trigonella (T. arabica Del.). The economic value of T. suavissima (and its symbiosis with Sinorhizobium) to the beef industry in the Channel Country is discussed.

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Smiles, D. E. y C. J. Smith. "A survey of the cation content of piggery effluents and some consequences of their use to irrigate soils". Soil Research 42, n.º 2 (2004): 231. http://dx.doi.org/10.1071/sr03059.

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Piggery effluent contains high concentrations of potassium, and its repeated irrigation raises soil exchangeable potassium to levels, relative to divalent cations, that may degrade soil structure. We surveyed 6 big piggeries extending from south-eastern Queensland on a self-mulching Vertosol, to an Arenic Rudosol in south-eastern South Australia. We sampled effluent used for irrigation and also soil profiles to permit 'fenceline' comparisons between soils that had and had not been irrigated. The major water-soluble cations sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+) were measured in the effluent and the soil saturation extracts, and also their exchangeable forms on air-dried soil samples. Ammonium-nitrogen (NH4+-N) was also assayed. The effluents were similar, with pH values between 7.5 and 8 together with very high water-soluble NH4-N, lower values for K+ and Na+, and quite low concentrations of Ca2+ and Mg2+. Cation concentrations varied across effluents; sodium and potassium adsorption ratios (SAR and KAR) were relatively constant but smaller than an ammonium adsorption ratio (Am-AR), which we conceive to estimate the influence of NH4+-N relative to the divalent cations in the effluent. Exchangeable K+ ratios in all profiles that had been irrigated were greater than their non-irrigated partners, as were the KAR values in their saturation extracts. Despite high concentrations of NH4+-N and high values of Am-AR in the effluents, there was no evidence of exchangeable NH4+ in the soils when sampled, which, we presume, is rapidly taken up by plants or oxidised. We present data that support a useful relationship between total cation content and effluent and the soil saturation extract electrical conductivity (EC), We also observed a modest increase in the EC of the saturation extract of irrigated soils. Farm records were insufficient to permit material balance calculations.

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Pickering, Bianca J., Jamie E. Burton, Trent D. Penman, Madeleine A. Grant y Jane G. Cawson. "Long-Term Response of Fuel to Mechanical Mastication in South-Eastern Australia". Fire 5, n.º 3 (3 de junio de 2022): 76. http://dx.doi.org/10.3390/fire5030076.

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Mechanical mastication is a fuel management strategy that modifies vegetation structure to reduce the impact of wildfire. Although past research has quantified immediate changes to fuel post-mastication, few studies consider longer-term fuel trajectories and climatic drivers of this change. Our study sought to quantify changes to fuel loads and structure over time following mastication and as a function of landscape aridity. Measurements were made at 63 sites in Victoria, Australia. All sites had been masticated within the previous 9 years to remove over-abundant shrubs and small trees. We used generalised additive models to explore trends over time and along an aridity gradient. Surface fuel loads were highest immediately post-mastication and in the most arid sites. The surface fine fuel load declined over time, whereas the surface coarse fuel load remained high; these trends occurred irrespective of landscape aridity. Standing fuel (understorey and midstorey vegetation) regenerated consistently, but shrub cover was still substantially low at 9 years post-mastication. Fire managers need to consider the trade-off between a persistently higher surface coarse fuel load and reduced shrub cover to evaluate the efficacy of mastication for fuel management. Coarse fuel may increase soil heating and smoke emissions, but less shrub cover will likely moderate fire behaviour.

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Ma, Long, Nirodha Weeraratne, Saliya Gurusinghe, Jesmin Aktar, K. M. Shamsul Haque, Philip Eberbach, Geoff G. Gurr y Leslie A. Weston. "Dung Beetle Activity Is Soil-Type-Dependent and Modulates Pasture Growth and Associated Soil Microbiome". Agronomy 13, n.º 2 (21 de enero de 2023): 325. http://dx.doi.org/10.3390/agronomy13020325.

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The introduction of numerous exotic dung beetles across southern Australia in regions where native dung beetles are not generally efficient in processing livestock dung has resulted in significant reductions in the quantity of such dung on the soil surface in recent years. However, the direct impacts of such ecosystem services on pasture quality and soil nutrient mobility have not yet been investigated in detail in the Riverina region of New South Wales (NSW), an area recognised for prime cattle and sheep production in Australia. Utilising 48 soil columns for lysimetry, we quantified the impact of a common introduced dung beetle (Bubas bison) in this region on water quality after permeation through four different soil types sown to winter annual pastures. Dung beetle treatments included dung plus dung beetles, dung alone and no dung beetles, and no dung as a control. Dung beetles and soil type impacts on the performance of improved overseeded annual pastures as measured by biomass accumulation was assessed over a four-month growing season. The four soil types, namely, Chromosol, Kandosol, Rudosol, and Vertosol, differed considerably with respect to their water-holding capacity and nutrient profiles, as assessed by initial soil testing and soil leachate evaluation following rainfall plus simulated rainfall events. The concentration of Escherichia coli resulting from cattle dung, cattle dung plus beetles, and the control soils without dung or beetles was assessed in collected leachates over a three-month period. E. coli numbers were significantly increased following B. bison activity, when compared to the dung-only and control treatments. Evaluation of the soil microbiome, by assessing genomic DNA in soils sampled 10 cm below the soil surface where dung beetles remained active following tunnelling, revealed significant differences among soil types with respect to bacterial and fungal communities. Within each soil type, dung beetle activity impacted the fungal community structure, but not the bacterial community. Pasture performance as assessed by biomass accumulation was significantly improved following dung beetle activity in later stages of pasture growth, while E. coli numbers and total coliforms appeared unaffected by beetle presence.

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21

Rujikiatkamjorn, Cholachat y Buddhima Indraratna. "Analytical solution for radial consolidation considering soil structure characteristics". Canadian Geotechnical Journal 52, n.º 7 (julio de 2015): 947–60. http://dx.doi.org/10.1139/cgj-2014-0277.

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A system of surcharge load combined with vertical drains to speed up consolidation of soft soil by reducing the drainage path is one of the most efficient and economical ground improvement techniques. In the field, conventional theories including smear zone have been commonly employed to predict the radial consolidation behaviour induced by vertical drains in soft clay. One of the key parameters in conventional analysis is the use of mean coefficient of volume compressibility and soil permeability, which are often assumed to be constant. The effect of drain installation on the soil compressibility of the in situ clay structure is often ignored. Laboratory testing has shown that the soil compressibility and permeability can vary nonlinearly over a considerable range of applied surcharge pressure, and both these properties can be affected during the drain installation. This study presents a mathematical model of radial consolidation via vertical drains incorporating the variations of soil compressibility and permeability as well as highlighting the effects of drain installation on those parameters. The main differences between the proposed and conventional models are elucidated, in terms of stress history and preloading (surcharge) pressure. The effects of preconsolidation pressure and the magnitude of applied preloading are examined through the dissipation of average excess pore pressure and associated settlement. Supported by experimental observations, the proposed theory is validated with field data of a selected case study in the town of Ballina, New South Wales, Australia.

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22

Kelly, B., C. Allan y 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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23

Moniodis, Jessie, Michael Renton, Christopher G. Jones, E. Liz Barbour y Margaret Byrne. "Genetic and environmental parameters show associations with essential oil composition in West Australian sandalwood (Santalum spicatum)". Australian Journal of Botany 66, n.º 1 (2018): 48. http://dx.doi.org/10.1071/bt17116.

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Santalum spicatum (R.Br.) A.DC is a West Australian sandalwood species highly valued for the sesquiterpene-rich oil in mature heartwood. The oil composition, particularly levels of the valuable sesquiterpenoids α- and β-santalol and the allergenic E,E-farnesol, are known to vary across its natural distribution. Our study investigated associations of oil characteristics in 186 S. spicatum trees in semiarid and arid regions of Western Australia with genetic structure, environmental parameters and morphological features. We found associations between oil composition and genetic structure, as well as between oil composition and environmental factors. Analysis of individuals using STRUCTURE revealed two major genetic clusters (K = 2), comprising trees from the arid north clustered together, and the semiarid south-west clustered separately. Mantel tests revealed a significant association between oil characteristics and genetic distance (r = 0.129, P = 0.02). There was considerable variation in the growing environment of S. spicatum. An Adonis test showed a significant association between oil composition and provenance (P = 0.001) and between oil composition and soil type (P = 0.002) but not oil composition and other environmental characters. Soil type was significantly related to santalol and E,E-farnesol content. No significant associations between oil composition and morphological features were identified.

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24

Stirling, G. R. y G. M. Lodge. "A survey of Australian temperate pastures in summer and winter rainfall zones: soil nematodes, chemical, and biochemical properties". Soil Research 43, n.º 8 (2005): 887. http://dx.doi.org/10.1071/sr05079.

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Data for soil nematode numbers, total microbial activity, microbial biomass carbon (C), and various soil chemical properties were collected from permanent and semi-permanent pastures at 108 locations in 2 contrasting environments: a summer rainfall zone in northern New South Wales (n = 60) and a winter rainfall zone in south-east South Australia and western Victoria (n = 48). Nematodes were also categorised according to their feeding habits and reproductive rates, and the abundance of various nematode groups was used to compute 3 indices that indicate the condition of the soil food web [enrichment index (EI), structure index (SI), and channel index (CI)]. At each location, pasture species herbage mass (kg DM/ha) was estimated and locations were grouped according to dominant species (lucerne, subterranean clover and phalaris in both rainfall zones; perennial ryegrass, winter rainfall zone only) as well as total soil microbial activity. The objective of the survey was to obtain a general indication of the biological status of soils used for pasture production in temperate regions of Australia, compare the soil biology in the 2 study areas, and determine whether it was influenced by pasture species composition. The most common plant-parasitic nematode was lesion nematode (Pratylenchus spp.), which was found at 67% of locations in the summer rainfall zone and 29% of those in the winter rainfall zone. Generally, there were more free-living nematodes in the soil than plant-parasitic nematodes. Numbers of free-living nematodes were highest in the winter rainfall zone, while in the summer rainfall zone there were more free-living nematodes in subterranean clover and phalaris pastures than lucerne pastures. Graphical representations of data for EI and SI indicated that the soil food webs at all sites in the summer rainfall zone were either structured or degraded. Food webs in the winter rainfall zone were more variable, with relatively high EI values indicating that more resources were available to support the soil biology. Climate had a major effect on CI values, with the mean in the winter rainfall zone being 28 (indicating a bacterial-dominant detritus food web) compared with 72 (indicating fungal dominance) in the summer rainfall zone. Mean total microbial activity was twice as high (2.6 v. 1.3 µg fluorescein diacetate/g.min) in soils from the winter than the summer rainfall zone. Mean levels of total organic C, total nitrogen, and labile C were also higher for the winter rainfall zone than the summer zone. For both rainfall zones, mean microbial biomass C was 0.09 mg/g soil, labile C was 9.05% of total organic C, and microbial biomass C was 3.5% of labile C. In the summer rainfall zone, values for all measured biochemical properties were lower in lucerne pastures than in other pasture types. We concluded that the biological status of soils in the winter rainfall zone was better than soils in the summer rainfall zone, and that the biology under lucerne pastures in the summer rainfall zone differed from pastures dominated by phalaris and subterranean clover. Soils in both study areas were generally healthy, as they had relatively high levels of total organic C and labile C, high numbers of free-living nematodes, high microbial activities, and a general lack of problems associated with plant-parasitic nematodes. However, there were exceptions, as there was considerable within-site variability for some biological and biochemical parameters at some sites.

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25

Albertsen, TO, RH Casey y KP Croker. "Accumulation and dissipation of dieldrin in mature wethers in the south-west of Western Australia". Australian Journal of Experimental Agriculture 35, n.º 3 (1995): 331. http://dx.doi.org/10.1071/ea9950331.

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The concentrations of dieldrin in body and wool fats of wethers grazed on 6 dieldrin-contaminated sites in the south-west of Western Australia were monitored over 2.5 years. Soil and pasture concentrations of dieldrin, a legacy of previous horticultural activities at these sites, were also measured. The concentrations of dieldrin in the soils varied from about 0.2 to 1.7 m a g . The production of the pastures at all sites showed a typical Mediterranean pattern with peak production in spring. The quantity of dry matter available ranged from <1000 kg/ha during summer-autumn to 10000 kg/ha in spring. In some samples the concentration of dieldrin in the dried plant material was above the accepted limit of 0.01 m a g for fresh material, but there were decreases over spring because of the substantial increase in the amount of dry matter available. The concentrations of dieldrin in the body and wool fats of the wethers increased during the winter and peaked at the start of spring, with the highest mean concentrations (mg/kg) in 1989 of 0.09-1.10 in body fats and 0.07-0.63 in wool fats. During spring the concentrations decreased and were at relatively low levels at the start of summer, with mean concentrations (mg/kg) of 0.02-0.72 in body fats and 0.01-0.18 in wool fats. Detailed results from 2 sites are discussed: Carbunup, with poorly structured loam soil; and Donnybrook, with good loam soil. On paddocks contaminated with dieldrin, production of wool with low concentrations of dieldrin is possible. If sheep grazed on contaminated paddocks are to be slaughtered, they should be sold in late spring, when concentrations of organochlorines in body fat should be low, or they should be run on uncontaminated land for about 2 months before their sale for slaughter.

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26

Pal, Y., R. J. Gilkes y M. T. F. Wong. "Mineral sources of potassium to plants for seven soils from south-western Australia". Soil Research 40, n.º 8 (2002): 1357. http://dx.doi.org/10.1071/sr02014.

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This investigation was conducted with surface horizon samples from 7 south-western Australian soils and their 3 size fractions (sand, silt, and clay). The K release of these materials was measured for several extractants; the highest amounts of K were released from the clay (<2 μm) fraction. The presence of sand-size feldspars and incomplete removal of attached organic matter resulted in sand releasing significant amounts of K. The proportions of total K released in boiling 1 m HNO3 by the sand, silt, and clay fractions ranged from 0.4 to 3.4%, 2.6 to 36.3%, and 11.2 to 51.4%, respectively, and from 2.0% to 22.9% for the whole soils. Cumulative K uptake by 6 harvests of ryegrass over 260 days ranged from 0.26 to 1.23 cmol/kg soil.The clay fraction released higher proportions of total K to acid compared with the sand and silt size fractions because of the high specific surface area of the clay and because it contained proportionately higher amounts of illite, which releases K by both ion exchange and dissolution, whereas K release from feldspars requires congruent dissolution of the silicate structure. The differences in contents of StepK (relatively available fraction of the non-exchangeable K) and CRK (constant rate K) for 1 m HNO3 dissolution of these soils and size fractions reflect differences in mineralogical composition between the soils and size fractions. The low contents of StepK for the sand fraction indicated that K was strongly retained by feldspars. The soils with high CRK values had significant amounts of illite in the clay fraction. Values of CRK were positively related to cumulative K uptake and cumulative dry matter yield of ryegrass.

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27

O'Sullivan, Cathryn A., Steven A. Wakelin, Ian R. P. Fillery, Adrienne L. Gregg y Margaret M. Roper. "Archaeal ammonia oxidisers are abundant in acidic, coarse-textured Australian soils". Soil Research 49, n.º 8 (2011): 715. http://dx.doi.org/10.1071/sr11288.

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The abundances of ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) in soils underlying pastures in the south-west of Western Australia (WA) were investigated. Samples were collected from irrigated pastures and one unmanaged (driveway) area during December 2009. Archaeal and bacterial ammonia monooxygenase (amoA) genes were quantified using real-time PCR, and the diversity of the archaeal amoA genes was investigated using denaturing gradient gel electrophoresis (PCR-DGGE). AOA amoA gene copies outnumbered AOB in all samples. Numbers of archaeal amoA genes ranged from 4.1E+01 to 1.34E+05 gene copies/ng soil DNA. Bacterial amoA genes were below detection limits at three of the four sample sites and ranged from 8.9E+01 to 6.7E+02 gene copies/ng soil DNA at the remaining site. Potential nitrification rates (PNR) were not correlated with AOA or AOB gene abundance, but high PNR only occurred at the site with measureable numbers of AOB. The DGGE analysis revealed that the AOA community was diverse and variability in banding patterns was significantly affected by both site and depth (P < 0.05). Statistical analysis matching biological variation (AOA amoA genotypes) to environmental variables (BEST analysis) revealed that pH was the key driver of AOA community structure (ρ = 0.72; P = 0.005). Soil pH was also inversely correlated to abundance of AOA amoA genes in soil (ρ = 0.8; P = 0.003). This study has shown that AOA are important members of the nitrogen-cycling community in acidic WA pasture soils, and likely in the wider agricultural soils of WA.

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28

Waymouth, Vicky, Rebecca E. Miller, Sabine Kasel, Fiona Ede, Andrew Bissett y Cristina Aponte. "Soil Bacterial Community Responds to Land-Use Change in Riparian Ecosystems". Forests 12, n.º 2 (28 de enero de 2021): 157. http://dx.doi.org/10.3390/f12020157.

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Riparian forests were frequently cleared and converted to agricultural pastures, but in recent times these pastures are often revegetated in an effort to return riparian forest structure and function. We tested if there is a change in the soil bacterial taxonomy and function in areas of riparian forest cleared for agricultural pasture then revegetated, and if soil bacterial taxonomy and function is related to vegetation and soil physicochemical properties. The study was conducted in six riparian areas in south-eastern Australia, each comprising of three land-use types: remnant riparian forest, cleared forest converted to pasture, and revegetated pastures. We surveyed three strata of vegetation and sampled surface soil and subsoil to characterize physicochemical properties. Taxonomic and functional composition of soil bacterial communities were assessed using 16S rRNA gene sequences and community level physiological profiles, respectively. Few soil physiochemical properties differed with land use despite distinct vegetation in pasture relative to remnant and revegetated areas. Overall bacterial taxonomic and functional composition of remnant forest and revegetated soils were distinct from pasture soil. Land-use differences were not consistent for all bacterial phyla, as Acidobacteria were more abundant in remnant soils; conversely, Actinobacteria were more abundant in pasture soils. Overall, bacterial metabolic activity and soil carbon and nitrogen content decreased with soil depth, while bacterial metabolic diversity and evenness increased with soil depth. Soil bacterial taxonomic composition was related to soil texture and soil fertility, but functional composition was only related to soil texture. Our results suggest that the conversion of riparian forests to pasture is associated with significant changes in the soil bacterial community, and that revegetation contributes to reversing such changes. Nevertheless, the observed changes in bacterial community composition (taxonomic and functional) were not directly related to changes in vegetation but were more closely related to soil attributes.

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29

Harper, R. J. y R. J. Gilkes. "The effects of clay and sand additions on the strength of sandy topsoils". Soil Research 42, n.º 1 (2004): 39. http://dx.doi.org/10.1071/sr03063.

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The clay contents of sandy soils in south-western Australia are often modified, either intentionally or inadvertently, as a result of management practices and erosion. Although the strength of sandy surfaced soils has previously been shown to be related to clay content, in natural soils the effects of induced changes in clay content on soil strength have not been assessed.Increasing amounts of subsoil clay were added to their respective topsoils in increments ranging from 5 to 20% by weight, and these systematically increased soil strength. A strong log–log relationship between clay content and soil strength explained 69% of the variation, with soil strength further affected by sodicity. This enhancement of soil strength has implications for the practice of claying water-repellent soils, particularly where non-uniform application or poor incorporation results in high concentrations of clay, where very high rates (e.g. 300 t/ha) of application are used, or where clayey subsoils are brought to the surface by deep cultivation or the removal of topsoils by erosion.Drift sand, with a clay content of around 1% and negligible strength, was added in increasing increments to typical topsoils, over the range of 0–100% by weight to replicate the effects of wind-induced deposition and winnowing of clay particles. Increasing additions of drift sand systematically decreased soil strength, with a log–log relationship between clay content and strength of the mixtures explaining 81% of the variation. This suggests that wind erosion, and the winnowing of clay or deposition of drift sand, permanently destabilises soil surfaces by reducing soil strength. It is feasible that strategic applications of sand on the surfaces of soils affected by hardsetting may reduce soil strength and encourage soil structure development and seedling emergence.

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30

Skjemstad, J. O., L. R. Spouncer, B. Cowie y R. S. Swift. "Calibration of the Rothamsted organic carbon turnover model (RothC ver. 26.3), using measurable soil organic carbon pools". Soil Research 42, n.º 1 (2004): 79. http://dx.doi.org/10.1071/sr03013.

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A fractionation scheme that provided the measurement of a labile pool (particulate organic carbon), a charcoal-carbon pool, and a humic pool by difference was tested as a means of initialising the Rothamsted organic carbon turnover model version 26.3. Equating these 3 fractions with the resistant plant material, inert organic matter, and humic pools of the model, respectively, gave good agreement between measured and modelled data for 2 long-term rotation trials in Australia using a soil depth of 30 cm. At one location, Brigalow Research Station in Queensland, there were 3 distinct soil types, two clays and a duplex soil, in a semi-arid, subtropical climate. At this site, continuous wheat with some sorghum was established after clearing land under brigalow (Acacia harpophylla) and continued for 18 years. The second location was near Tarlee, South Australia, and was established on existing agricultural land. One soil type (red brown earth) with 2 rotations (continuous wheat and wheat–fallow) were available over a period of 8 years.The modelled and measured data were in good agreement for both locations but the level of agreement was substantially improved when the resistant plant material decomposition rate was reduced from 0.3 to 0.15/year. No other modifications were required and the resulting values provided excellent agreement between the modelled and measured data not only for the total soil organic carbon but also for the individual pools. Using this fractionation scheme therefore provides an excellent means of initialising and testing the Rothamsted model, not only in Australia, but also in countries with similar soil types and climate.For the first time, the work reported here demonstrates a methodology linking measured soil carbon pools with a conceptual soil carbon turnover model. This approach has the advantage of allowing the model to be initialised at any point in the landscape without the necessity for historical data or for using the model itself to generate an initial equilibrium pool structure. The correct prediction of the changing total soil organic carbon levels, as well as the pool structure over time, acts as an internal verification and gives confidence that the model is performing as intended.

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31

Wahren, C. H., R. J. Williams y W. A. Papst. "Alpine and Subalpine Wetland Vegetation on the Bogong High Plains, South-eastern Australia". Australian Journal of Botany 47, n.º 2 (1999): 165. http://dx.doi.org/10.1071/bt97106.

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The botanical composition and structure of wetland vegetation from seven sites in the alpine and subalpine tracts of the Bogong High Plains was sampled in 1995 and 1996. Sites were in the vicinity of Mts Nelse, Cope and Fainter. Sampling was based on contiguous 1-m2 quadrats along transects 20−70 m long across each wetland. Samples were ordinated using non-metric multidimensional scaling (NMDS). Floristic variation was assessed both within selected individual wetlands, and between wetlands from different regions. The relationship between the ordinations and environmental variables such as soil surface texture, soil depth and the amount of bare ground was tested by fitting vectors. Three dominant vegetation assemblages were identified. Closed heath, of hygrophyllous, scleromorphic shrubs such as Richea continentis and Baeckea gunniana, the rush Empodisma minus and the moss Sphagnum cristatum occurred on the deeper peats. Low open heath of Epacris glacialis and Danthonia nivicola occurred on shallow peats. Herbfields of Caltha introloba and Oreobolus pumilio occurred on stony pavements in two different physiographic situations&horbar;on relatively steep slopes (10−20°) at the head of wetlands, and on flat ground (slope < 2°), below the head of wetlands. The pavements on the steeper sites appeared to be associated with periglacial features such as solifluction lobes and terraces. Those on the flatter ground appeared to have been derived more recently. Wetlands in the Mt Cope region consisted of closed heath, low open heath and pavement herbfield in various proportions. Wetlands on Mt Fainter, which are subject to heavy trampling by cattle, were in a degraded condition, with a low cover of major hygrophyllous mosses and shrubs, and a high cover of introduced species. Long-ungrazed wetlands in a 50-year exclosure at Rocky Valley had high cover of closed heath, no pavements, numerous ponds and virtually no entrenched drainage channels or exposed peat. The Caltha herbfields are significant features nationally, both floristically and geomorphologically. Alpine and subalpine wetlands have been listed under the Victorian Flora and Fauna Guarantee Act 1988, and continued grazing by cattle is not compatible with the conservation objectives for this alpine vegetation type.

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32

Evans, Jason P., Xianhong Meng y Matthew F. McCabe. "Land surface albedo and vegetation feedbacks enhanced the millennium drought in south-east Australia". Hydrology and Earth System Sciences 21, n.º 1 (24 de enero de 2017): 409–22. http://dx.doi.org/10.5194/hess-21-409-2017.

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Abstract. In this study, we have examined the ability of a regional climate model (RCM) to simulate the extended drought that occurred throughout the period of 2002 through 2007 in south-east Australia. In particular, the ability to reproduce the two drought peaks in 2002 and 2006 was investigated. Overall, the RCM was found to reproduce both the temporal and the spatial structure of the drought-related precipitation anomalies quite well, despite using climatological seasonal surface characteristics such as vegetation fraction and albedo. This result concurs with previous studies that found that about two-thirds of the precipitation decline can be attributed to the El Niño–Southern Oscillation (ENSO). Simulation experiments that allowed the vegetation fraction and albedo to vary as observed illustrated that the intensity of the drought was underestimated by about 10 % when using climatological surface characteristics. These results suggest that in terms of drought development, capturing the feedbacks related to vegetation and albedo changes may be as important as capturing the soil moisture–precipitation feedback. In order to improve our modelling of multi-year droughts, the challenge is to capture all these related surface changes simultaneously, and provide a comprehensive description of land surface–precipitation feedback during the droughts development.

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33

Howell, Jocelyn, Geoff S. Humphreys y Peter B. Mitchell. "Changes in soil water repellence and its distribution in relation to surface microtopographic units after a low severity fire in eucalypt woodland, Sydney, Australia". Soil Research 44, n.º 3 (2006): 205. http://dx.doi.org/10.1071/sr04176.

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The distribution and persistence of water repellence was altered by low severity fire and subsequent rain in soil supporting eucalypt woodland on sandstone terrain in Sydney, south-eastern Australia. Water drop penetration times were recorded to depths of 0.08 m in situ 9 months before the experimental fire, immediately after fire, 4 weeks later when rainfall had modified the soil surface but the soil was dry, and 5 weeks after the fire when the soil was moist. Spatial variation in water repellence was high in all cases except immediately after the fire, when soil was almost uniformly strongly repellent to 0.03 m depth, and less uniformly repellent at 0.04–0.06 m depth. Heavy rain moved litter, ash, and mineral soil, modifying the soil surface into microtopographic units including litter dams, microterraces, and other areas with differing proportions of litter, bare soil, and gravel. Post-rain water drop penetration measurements were taken on and beneath these different surface conditions, in order to investigate the possible contribution of water repellence to the formation and maintenance of litter dams and microterraces characteristic of this terrain after fire. Water repellence did not appear to be directly correlated with the presence or absence of surface litter. Results suggest the long-term and spatially variable water repellence found in soils associated with vegetation dominated by eucalypts in Australia is maintained by factors different from those causing extreme and uniform water repellence after fire. Variable water repellence at the soil surface and within the profile may contribute to differential survival of seedlings after fire. The possible breakdown of water repellent compounds formed after fire and the distribution and development of hydrophobic biotic structures including fungal hyphae and proteoid roots need to be investigated.

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34

Sadras, V. O. y D. Rodriguez. "The limit to wheat water-use efficiency in eastern Australia. II. Influence of rainfall patterns". Australian Journal of Agricultural Research 58, n.º 7 (2007): 657. http://dx.doi.org/10.1071/ar06376.

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We investigated the influence of rainfall patterns on the water-use efficiency of wheat in a transect between Horsham (36°S) and Emerald (23°S) in eastern Australia. Water-use efficiency was defined in terms of biomass and transpiration, WUEB/T, and grain yield and evapotranspiration, WUEY/ET. Our working hypothesis is that latitudinal trends in WUEY/ET of water-limited crops are the complex result of southward increasing WUEB/T and soil evaporation, and season-dependent trends in harvest index. Our approach included: (a) analysis of long-term records to establish latitudinal gradients of amount, seasonality, and size-structure of rainfall; and (b) modelling wheat development, growth, yield, water budget components, and derived variables including WUEB/T and WUEY/ET. Annual median rainfall declined from around 600 mm in northern locations to 380 mm in the south. Median seasonal rain (from sowing to harvest) doubled between Emerald and Horsham, whereas median off-season rainfall (harvest to sowing) ranged from 460 mm at Emerald to 156 mm at Horsham. The contribution of small events (≤ 5 mm) to seasonal rainfall was negligible at Emerald (median 15 mm) and substantial at Horsham (105 mm). Power law coefficients (τ), i.e. the slopes of the regression between size and number of events in a log-log scale, captured the latitudinal gradient characterised by an increasing dominance of small events from north to south during the growing season. Median modelled WUEB/T increased from 46 kg/ha.mm at Emerald to 73 kg/ha.mm at Horsham, in response to decreasing atmospheric demand. Median modelled soil evaporation during the growing season increased from 70 mm at Emerald to 172 mm at Horsham. This was explained by the size-structure of rainfall characterised with parameter τ, rather than by the total amount of rainfall. Median modelled harvest index ranged from 0.25 to 0.34 across locations, and had a season-dependent latitudinal pattern, i.e. it was greater in northern locations in dry seasons in association with wetter soil profiles at sowing. There was a season-dependent latitudinal pattern in modelled WUEY/ET. In drier seasons, high soil evaporation driven by a very strong dominance of small events, and lower harvest index override the putative advantage of low atmospheric demand and associated higher WUEB/T in southern locations, hence the significant southwards decrease in WUEY/ET. In wetter seasons, when large events contribute a significant proportion of seasonal rain, higher WUEB/T in southern locations may translate into high WUEY/ET. Linear boundary functions (French-Schultz type models) accounting for latitudinal gradients in its parameters, slope, and x-intercept, were fitted to scatter-plots of modelled yield v. evapotranspiration. The x-intercept of the model is re-interpreted in terms of rainfall size structure, and the slope or efficiency multiplier is described in terms of the radiation, temperature, and air humidity properties of the environment. Implications for crop management and breeding are discussed.

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35

Low, AB y BB Lamont. "Aerial and Belowground Phytomass of Banksia Scrub-Heath at Eneabba, South-Western Australia". Australian Journal of Botany 38, n.º 4 (1990): 351. http://dx.doi.org/10.1071/bt9900351.

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Three Banksia spp. accounted for 80% of the aerial biomass of scrub-heath on deep sand. Reproductive structures contributed relatively more than leaves or stems to biomass of a non-sprouting Banksia, which also retained most of its dead leaves, than to the two resprouting species. Sclerophyllous hemicryptophytes accounted for only 1% of the aerial biomass. Litter contributed 19% of above-ground dead plus live phytomass and was poorly decomposed. The overall root f shoot ratio, to a depth of 2.5 m, was a high 2.35. Rootstocks, laterals and proteoid roots made major contributions to below-ground phytomass even though they were confined to the uppermost 15 cm of soil. Despite an exponential decline in root mass with depth, the gradient was less than in related ecosystems due to the abundance of well developed tap roots and vertical laterals (sinkers) to a depth of at least 5 m.

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36

L. Specht, Raymond, Gloria Montenegro y Mary E. Dettmann. "Structure and Alpha Biodiversity of Major Plant Communities in Chile, a Distant Gondwanan Relation". Journal of Environment and Ecology 6, n.º 1 (8 de junio de 2015): 21. http://dx.doi.org/10.5296/jee.v6i1.7780.

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The structure, growth and biodiversity of Chilean vegetation are explored from the arid north, through the Mediterranean-climate zone of Central Chile to the evergreen and semi-deciduous Nothofagus vegetation in the south and into the treeless wet-heath vegetation of the Magellanic islands. The northern Desert Zone has four to six genera of plants that have been recorded in Australia, while the southern vegetation reveals many relationships with the cool temperate vegetation of Australia with which Chile was conjoined in the Gondwanan assembly during the Late Mesozoic. As the physico-chemical processes that determine the structure, growth and biodiversity of plant communities on median-nutrient soils are similar in the temperate climates of Chile and Australia, similar values of Foliage Projective Cover, Leaf Area, Leaf Specific Weight and Alpha Biodiversity result.

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37

Hayes, R. C., I. Ara, W. B. Badgery, R. A. Culvenor, R. E. Haling, C. A. Harris, G. D. Li et al. "Prospects for improving perennial legume persistence in mixed grazed pastures of south-eastern Australia, with particular reference to white clover". Crop and Pasture Science 70, n.º 12 (2019): 1141. http://dx.doi.org/10.1071/cp19063.

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This review examines the prospect of improving perennial legume adaptation to grazed mixed pasture swards across the higher-altitude regions of south-eastern Australia through improved management, particularly as it relates to soil fertility. The range of adapted perennial species available to farmers often remains limited to only one perennial forage legume species, white clover (Trifolium repens L.). Despite recent advances in cultivars for increased persistence in dryland environments, white clover remains sensitive to drought with its inherently shallow root system and limited capacity to restrict water loss from herbage. With few alternative species likely to become widely available in the foreseeable future, prospects for extending the boundaries of perennial legume adaptation likely rely on a dual approach of improving soil fertility and further genetic improvement in white clover. Improved soil fertility would focus on overcoming soil acidity and addressing nutrient deficiencies, particularly of phosphorus, potassium, boron and molybdenum, which tend to be more widespread in the target region. Addressing these soil constraints would alleviate periodic moisture stress by: (1) increased water availability through improved infiltration and soil hydraulic properties; (2) increased root growth to maximise exploration of the soil volume; and (3) better maintenance of plant cell structures to foster improved osmotic regulation. However, the extent to which white clover adaption may be extended remains an issue of further research. This review highlights an opportunity for further genetic improvement of white clover by focusing on improving the capacity to recover from periodic droughts through seedling regeneration. Further breeding efforts in white clover should examine the feasibility of selecting for hard seed characteristics more similar to the best-adapted subterranean clover (Trifolium subterraneum L.) cultivars across this region to promote ongoing seedling regeneration.

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38

Thomas, G. A., R. C. Dalal, E. J. Weston, K. J. Lehane, A. J. King, D. N. Orange, C. J. Holmes y G. B. Wildermuth. "Pasture - crop rotations for sustainable production in a wheat and sheep-based farming system on a Vertosol in south-west Queensland, Australia". Animal Production Science 49, n.º 8 (2009): 682. http://dx.doi.org/10.1071/ea07170.

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Rainfed grain production, based on winter cereals, is marginal in south-west Queensland, Australia, because of low and variable rainfall and high evapotranspiration. Also, grain yield and grain quality have decreased as soil fertility, particularly soil nitrogen supply, has declined on older cropping lands. An option for improving soil N supply is to include legume-based pastures in rotation with winter cereals. The objective of this study was to determine the effects of short-term (18 months) legume pastures (annual medics and lucerne + annual medics), and longer term (3 years) mixed grass (Bambatsi panic) and legume (lucerne + annual medics) pasture phases on sheep production and on soil water and N supply and production of subsequent wheat crops on a grey Vertosol soil. Two separate phases of annual medics and lucerne + annual medics pastures produced mean total aboveground dry matter yield of 7.10 t/ha of annual medics and 5.80 t/ha of lucerne + annual medics over the 18-month periods. For two phases of the grass + legume pastures, mean total aboveground dry matter yield was 3.95 t/ha for grass and 8.19 t/ha for legume over 3 years. Over an 18-month period, sheep bodyweight gains and fleece weights were similar for the annual medics, lucerne + annual medics and grass + legume pastures and were approximately five times greater than those from native pasture as a result of the greater stocking rate possible on the sown pastures. Greater drying of the soil profile occurred following lucerne + annual medics and grass + legume pasture phases than continuous wheat, resulting in lower soil water content at sowing of wheat crops following these pasture phases on several occasions. Mean soil nitrate-N benefits before wheat sowing in the first year following termination of the 18-month annual medics, lucerne + annual medics, and the 3-year grass + legume pasture phases were 45, 44 and 42 kg N/ha, respectively. Grain N yields and gross margins of the first wheat crops following the 18-month annual medics, lucerne + annual medics, and the 3-year grass + legume pasture phases were similar in value to continuous wheat with ~60, 80, and 40–60 kg N/ha fertiliser applied at sowing, respectively. Improvements in grain N yield and gross margin were still evident in the fifth wheat crop following annual medics and lucerne + annual medics pastures and in the third wheat crop following grass + legume pasture, compared with continuous wheat without N fertiliser addition. Total gross margins from 1996 to 2005 were 1.6–2.5 times greater for the pasture–crop rotations than continuous wheat where no N fertiliser was applied to wheat. However, gross margins were greater in continuous wheat than in pasture–crop rotations where N fertiliser was applied to target prime hard grade grain protein in wheat. The 3-year grass + legume pasture phase showed potential to improve surface soil structure and water infiltration and to reduce decline in soil organic carbon concentration at 0–0.1 m depth, compared with continuous wheat cropping and shorter-term legume pasture phases.

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39

McKenzie, Neil y David Jacquier. "Improving the field estimation of saturated hydraulic conductivity in soil survey". Soil Research 35, n.º 4 (1997): 803. http://dx.doi.org/10.1071/s96093.

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Prediction of the movement and storage of water in soil is central to quantitative land evaluation. However, spatial and temporal predictions have not been provided by most Australian soil surveys. The saturated hydraulic conductivity (Ks) is an essential parameter for description of water movement in soil and its estimation has been considered too difficult for logistic and technical reasons. The Ks cannot be measured everywhere and relationships with readily observed morphological variables have to be established. However, conventional morphology by itself is a poor predictor of Ks. We have developed a more functional set of morphological descriptors better suited to the prediction of Ks. The descriptors can be applied at several levels of detail. Measurements of functional morphology and Ks were made on 99 horizons from 36 sites across south-eastern Australia. Useful predictions of Ks were possible using field texture, grade of structure, areal porosity, bulk density, dispersion index, and horizon type. A simple visual estimate of areal porosity was satisfactory, although a more quantitative system of measurement provided only slightly better predictions. Regression trees gave more plausible predictive models than standard multiple regressions because they provided a realistic portrayal of the non-additive and conditional nature of the relationships between morphology and Ks. The results are encouraging and indicate that coarse-level prediction of Ks is possible in routine soil survey. Direct measurement of Ks does not appear to be generally feasible because of the high cost, dynamic nature of Ks, and substantial short-range variation in the field. Prediction is further constrained by the limited returns from more sophisticated morphological predictors. The degree to which this limits practical land evaluation is yet to be demonstrated.

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40

Officer, S. J., V. M. Dunbabin, R. D. Armstrong, R. M. Norton y G. A. Kearney. "Wheat roots proliferate in response to nitrogen and phosphorus fertilisers in Sodosol and Vertosol soils of south-eastern Australia". Soil Research 47, n.º 1 (2009): 91. http://dx.doi.org/10.1071/sr08089.

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Root growth responses to separately placed of bands of N and P fertiliser were examined at the 3-leaf (GS13) and stem extension growth stages (GS30) for wheat (Triticum aestivum L. cv. Yitpi) growing in 2 major alkaline soil types from the rainfed (375–420 mm) grain production regions of south-eastern Australia. Intact cores of a Sodosol and a Vertosol were destructively sampled and changes in root length density (RLD) and root diameter distribution within the soil profile were examined using restricted maximum likelihood analysis and principal component analysis, respectively. At GS13, RLD increased in the Vertosol when only P was applied, although there was no shoot growth response. The root response to P consisted of a spatially generalised increase in RLD, rather than a specific increase in the vicinity of the P fertiliser band. There was a substantially greater, but still generalised, increase in RLD in the Vertosol when both N and P fertiliser were applied, although there was no response to N fertiliser (without P). The distribution of root length in diameter classes changed with depth in the profile at GS13 but was otherwise similar, regardless of soil types and fertiliser treatment. The root responses to fertiliser at GS30 also consisted of a generalised proliferation of RLD in the topsoil, with no detectable fertiliser-specific changes in the location or structure of the root system. Shoot and root growth increased to a similar level at GS30 when plants were supplied with N, irrespective of P, and root diameter distributions were again insensitive to fertiliser treatment. Plants responded to N by increasing the RLD of relatively fine roots (100–250 μm), which was a P style of acquisition strategy that was possibly triggered by moisture limitations. Consequently, the root responses to fertiliser under realistic semi-arid conditions did not follow expectations based on nutrient acquisition studies. Instead, wheat plants responded to N or P fertiliser with a generalised proliferation of fine roots, apparently to better compete for finite water and nutrients.

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41

Preeti, Preeti, Yuri Shendryk y Ataur Rahman. "Identification of Suitable Sites Using GIS for Rainwater Harvesting Structures to Meet Irrigation Demand". Water 14, n.º 21 (31 de octubre de 2022): 3480. http://dx.doi.org/10.3390/w14213480.

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This study uses a multi-criteria decision analysis approach based on geographic information system (GIS) to identify suitable sites for rainwater harvesting (RWH) structures (such as farm dam, check dam and contour bund) to meet irrigation demand in Greater Western Sydney region, New South Wales, Australia. Data on satellite image, soil, climate, and digital elevation model (DEM) were stored in GIS layers and merged to create a ranking system, which were then used to identify suitable RWH (rainwater harvesting) areas. The resulting thematic layers (such as rainfall, land use/land cover, soil type, slope, runoff depth, drainage density, stream order and distance from road) were combined into one overlay to produce map of RWH suitability. The results showed that 9% of the study region is ‘very highly suitable’ and 25% is ‘highly suitable’. On the other hand, 36% of the area, distributed in the north-west, west and south-west of the study region, is ‘moderately suitable’. While 21% of the region, distributed in east and south-east part of the region, has ‘low suitability’ and 9% is found as ‘unsuitable area’. The findings of this research will contribute towards wider adoption of RWH in Greater Western Sydney region to meet irrigation demand. The developed methodology can be adapted to any other region/country.

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42

Bougoure, Jeremy, Mark Brundrett, Andrew Brown y Pauline F. Grierson. "Habitat characteristics of the rare underground orchid Rhizanthella gardneri". Australian Journal of Botany 56, n.º 6 (2008): 501. http://dx.doi.org/10.1071/bt08031.

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Rhizanthella gardneri R.S.Rogers is an entirely subterranean mycoheterotrophic orchid known only from two isolated populations within south-western Western Australia (WA). This rare species appears restricted to habitats dominated by species of the Melaleuca uncinata complex. R. gardneri purportedly forms a tripartite relationship with Melaleuca1, via a connecting mycorrhizal fungus, for the purpose of carbohydrate and nutrient acquisition. Here, we quantify key climate, soil and vegetation characteristics of known R. gardneri habitats to provide baseline data for monitoring of known R. gardneri populations, to better understand how R. gardneri interacts with its habitat and to identify possible new sites for R. gardneri introduction. We found that the habitats of the two known R. gardneri populations show considerable differences in soil chemistry, Melaleuca structure and Melaleuca productivity. Multivariate analyses showed that both multidimensional scaling (MDS) and principal components analysis (PCA) ordinations of soil chemical characteristics were very similar. Individual sites within populations were relatively similar in all attributes measured, whereas overall northern and southern habitats were distinct from each other. These results suggest that R. gardneri can tolerate a range of conditions and may be more widespread than previously thought, given that there are extensive areas of Melaleuca thickets with similar habitat characteristics across south-western WA. Variability within the habitats of known R. gardneri populations suggests translocation of this species into sites with similar vegetation may be a viable option for the survival of this species.

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43

Scott, B. J., M. R. Fleming, M. K. Conyers, K. Y. Chan y P. G. Knight. "Lime improves emergence of canola on an acidic, hardsetting soil". Australian Journal of Experimental Agriculture 43, n.º 2 (2003): 155. http://dx.doi.org/10.1071/ea01127.

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Much of the agricultural lime applied in southern New South Wales, Australia, is applied to crops of canola (Brassica napus L.), but little is documented on the response of canola to lime. The few documented responses in grain yield of canola to lime application have been ascribed to decreased toxicities of aluminium and manganese. However, there is evidence that lime can have a structural effect on soil. A field experiment was limed in 1982 (0–5 t/ha) and was relimed in 1996 (0–5 t/ha) to give factorial combinations of 5 rates of 'old' (1982) and 6 rates of 'new' (1996) lime. When sown to canola in 1999 there was an increase in density of canola (from 17�to�60�plants/m2) and grain yield (from 1200 to 2700 kg/ha) associated with increasing rates of lime application. The emergence of canola was increased by 15% for each 1 unit increase in soil pHCa. Two subsequent pot experiments, conducted on cores taken from a subset of field plots with different liming histories, showed that lime application increased emergence of canola by about 9% for each 1 unit increase in soil pHCa. In addition, 2 contrasting watering treatments (gentle spraying and rapid flooding) were applied to the pots to either avoid or accentuate any soil structural breakdown. Flooding gave lower emergence compared with spraying (19 and 31%, respectively). Soil strength measurements (penetration resistance and shear strength) conducted on the surface soil (0–1 cm depth) during the second glasshouse experiment showed that lime application and gentle watering (spraying rather than flooding) resulted in lower soil strength. The soil strength measurements were related to emergence of canola. It is proposed that soil structural stability was the major contributor to these observed emergence differences. This is the first evidence in New South Wales of lime affecting plant performance via its influence on soil structure.

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44

Chan, K. Y., A. M. Bowman, W. Smith y R. Ashley. "Restoring soil fertility of degraded hardsetting soils in semi-arid areas with different pastures". Australian Journal of Experimental Agriculture 41, n.º 4 (2001): 507. http://dx.doi.org/10.1071/ea00052.

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To evaluate the effectiveness of a pasture phase in restoring soil fertility, changes in concentration of organic carbon, physical and chemical properties of degraded hardsetting red soils (Alfisols) were assessed at 3 sites in the semi-arid central western region of New South Wales 3–4 years after conversion to different pastures. The pasture species included an annual grass, ryegrass (Lolium rigidum cv. Wimmera), an annual legume, barrel medic (Medicago truncatulata cv. Sephi) as well as a perennial grass, Consol lovegrass (Eragrostis curvula), and a perennial legume, lucerne (Medicago sativa cv. Trifecta). Significant differences in concentration of organic carbon in soils were found only in the top 0–2.5 cm even after 3–4 years under perennial pastures. The concentration of organic carbon under annual grass pasture did not differ from that in the fallow. Corresponding to the organic carbon concentrations, significant changes in water-stable aggregation (detectable to 20 cm depth) and hydraulic properties (up to a 5-fold difference in sorptivity, namely 0.29 mm/h 0.5 under fallow to 1.42 mm/h 0.5 under lucerne) were observed under perennial pastures when compared with that of the fallow. Of the 2 perennial pastures, Consol lovegrass and lucerne were both effective in promoting soil friability as well as water-stable aggregation. However, lucerne increased mineralisable nitrogen more than Consol lovegrass (by up to 4.6 times more, equivalent to 11.6 mg/kg in the 0–10-cm layer). Our results highlight the potential benefits of perennial pastures in maintaining the quality of the fragile hardsetting soils in the low rainfall areas. However, due to the slow rate and the restricted depth of improvement (0–2.5 cm), apart from incorporation of a pasture phase in the cropping system, soil management that maintains soil organic matter level and soil structure, namely reduced tillage and stubble retention, should also be adopted. These findings should be relevant to the management of the hardsetting soils that occupy 12% of the land area of Australia, particularly those in the lower rainfall areas.

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45

Foreman, Paul W. "A framework for testing the influence of Aboriginal burning on grassy ecosystems in lowland, mesic south–eastern Australia". Australian Journal of Botany 64, n.º 8 (2016): 626. http://dx.doi.org/10.1071/bt16081.

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The complex interactions among climate, soils, fire and humans in the biogeography of natural grasslands has long been debated in Australia. On the one hand, ecological models assume the primacy of climate and soils. On the other, Aboriginal burning is hypothesised to have altered the entire continent since before the last glacial maximum. The present paper develops a framework to test for the ‘fingerprint’ of Aboriginal burning in lowland, mesic grassy ecosystems of south-eastern Australia, using ecological theory, and the ethno-historical record. It is clear that fire-stick farming was used to promote staple roots in south-eastern Australia and, in some instances, it has been shown to influence grassland–woodland boundaries. The framework comprises the following three evidence lines: (1) archival benchmarking and palaeoecology; (2) phytoecology; and (3) ethnology and archaeology. That fire-stick farming was likely instrumental in grassland formation and maintenance must be supported by evidence that shows that ‘natural’ grasslands exist in climatically–edaphically unexpected places, that fine-scale patterns and dynamics are at least partly due to fire and that the fire regime has been influenced by Aboriginal burning. Application of the framework indicated that widespread Aboriginal burning for staple foods likely extended the area of temperate grasslands and influenced their structure and function.

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46

Mele, P. M. y M. R. Carter. "Impact of crop management factors in conservation tillage farming on earthworm density, age structure and species abundance in south-eastern Australia". Soil and Tillage Research 50, n.º 1 (febrero de 1999): 1–10. http://dx.doi.org/10.1016/s0167-1987(98)00189-5.

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47

Yates, Colin J. y Richard J. Hobbs. "Temperate Eucalypt Woodlands: a Review of Their Status, Processes Threatening Their Persistence and Techniques for Restoration". Australian Journal of Botany 45, n.º 6 (1997): 949. http://dx.doi.org/10.1071/bt96091.

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Temperate eucalypt woodlands were once widespread throughout southern Australia and Tasmania. Following European settlement, woodlands were cleared for agriculture, or grazed and converted to pasture. In the wheatbelts of south-western and south-eastern Australia, woodlands have been almost completely eliminated from the landscape with as little as 3% of some woodland types remaining. As a consequence, some temperate eucalypt woodland communities are amongst the most poorly conserved ecosystems in Australia. The main effect of widespread clearing and grazing has been the loss of habitat. This has had a devastating impact on the woodland flora and fauna. A number of species have become extinct and many are threatened; many others have undergone regional and local population declines. Woodlands now occur throughout much of their former range as remnants of varying size, quality and isolation. Many of these are under threat from further clearing, rising saline water tables and increased inundation, livestock grazing, nutrient enrichment, soil structural decline, altered fire regimes and the invasion of exotic weeds. The degradation and loss of biodiversity in temperate eucalypt woodlands will continue unless clearing stops and the management of remnants changes; this will invariably involve ecological restoration both at the patch and landscape level. The review discusses approaches to restoration and reveals that there are few data in the published literature describing techniques for reversing degrading processes and restoring diversity structure and function in remnant woodlands. This information is urgently needed. Past research on temperate eucalypt woodlands has focused on identifying the processes of degradation and these are now relatively well documented. There is a need to shift the focus of research to developing solutions for these problems.

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48

Monamy, Vaughan y Barry J. Fox. "Differential habitat use by a local population of subadult common dunnarts, Sminthopsis murina, following wildfire in coastal wet heath, New South Wales, Australia". Wildlife Research 32, n.º 7 (2005): 617. http://dx.doi.org/10.1071/wr04105.

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Little has been published about Sminthopsis murina, a small insectivorous marsupial encountered infrequently during trapping studies. Individuals favour vegetation associations found in recently burnt heathlands and forests; however, individuals rarely remain in such areas long enough for repeated capture. We report an unusual occurrence of habitat fidelity by a dense population of subadult S. murina in coastal wet heath, New South Wales, Australia. Individuals were captured repeatedly in the first 16 months following wildfire (30 subadults trapped 154 times: recapture rate = 80%). Densities peaked 10 months after fire at 3.75 individuals ha–1. More males than females were captured (23 males, 7 females). Habitat analyses revealed differential use of regenerating coastal wet heathland by S. murina. Significantly more captures were made in areas of high soil moisture in the first six months following fire. Captures then decreased in these areas but increased where soil moisture had been lower and where vegetation had been growing more slowly. Beyond the 1995/96 breeding season, regenerating vegetation became increasingly dense and less patchy and captures of S. murina ultimately declined to zero. This paper records a rare opportunity to examine habitat preferences of a single cohort of subadult S. murina. Habitat use may have been determined by the presence of a narrow range of vegetation structure.

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Rab, M. A., P. D. Fisher, R. D. Armstrong, M. Abuzar, N. J. Robinson y S. Chandra. "Advances in precision agriculture in south-eastern Australia. IV. Spatial variability in plant-available water capacity of soil and its relationship with yield in site-specific management zones". Crop and Pasture Science 60, n.º 9 (2009): 885. http://dx.doi.org/10.1071/cp08350.

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Spatial variability in grain yield can arise from variation in many different soil and terrain properties. Identification of important sources of variation that bear significant relationship with grain yield can help achieve more effective site-specific management. This study had three aims: (i) a geostatistical description/modelling of the paddock-level spatial structure in variability of plant-available water capacity (PAWC) and related soil properties, (ii) to determine optimal number of management zones in the paddock, and (iii) to assess if the variability in PAWC and related soil properties is significantly associated with the variability in grain yield across the management zones. Particle size distribution, bulk density (BD), field capacity (FC), permanent wilting point (PWP), and soil water content (SWC) at sowing were measured at 4 soil depths (to 0.60 m) at 50 representative spatial sampling locations across a paddock near Birchip (Victoria). PAWC and plant-available water at sowing (PAWs) were derived from these data. Moderate to strong spatial dependence across the paddock was observed. The magnitude of the structural variation and of range varied widely across different soil properties and depths. The south-east edge and the central areas of the paddock had higher clay content, FC, PWP, PAWC, and lower PAWs. The paddock was divided into 6 potential management zones using combined header yield and normalised difference vegetation index (NDVI). The adequacy of zoning was evaluated using relative variability (RV) of header yield and soil properties. The mean RV for 3 zones differed little from that of 6 management zones for header yield and for each measured soil property, indicating division of the paddock into 3 zones to be adequate. The results from residual maximum likelihood (ReML) analysis showed that low yield zones had significantly higher clay content, FC, PWP, SWC, and PAWC and significantly lower PAWs than both medium and high yield zones. The mean FC, PWP, and PAWC in the low yield zones were, respectively, 25%, 26%, and 28% higher, and PAWs 36% lower than their corresponding values in the high yield zones. Linear regression analysis indicated that 59–96% of the observed variation in grain yield across management zones could be explained by variation in PWP. The practical implications of these results are discussed.

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Borchard, Philip, Ian A. Wright y Clare McArthur. "Do bare-nosed wombat (Vombatus ursinus) mounds influence terrestrial macroinvertebrate assemblages in agricultural riparian zones?" Australian Journal of Zoology 57, n.º 5 (2009): 329. http://dx.doi.org/10.1071/zo09060.

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Riparian ecosystems contain a complex mosaic of habitat structure types that can support distinct macroinvertebrate communities. Bare-nosed wombats (Vombatus ursinus) are often an integral component of agricultural riparian systems in south-eastern Australia. In these systems, wombats construct large burrow systems and mounds in the stream banks. Wombat mound structures vary markedly from the surrounding landscape and they may influence macroinvertebrate assemblages. We examined this ecosystem-engineering role of wombats as well as the ecological variability within our agricultural riparian study sites on the possible influence on macroinvertebrate assemblages. There were no detectable effects of wombat mounds on the richness or abundance of macroinvertebrates on the soil surface. At the site level, however, macroinvertebrate assemblages were most influenced by litter depth, upper canopy cover, cattle hoof prints and slope. The ecological variables within the study sites strongly affected macroinvertebrate assemblages. These findings reflect an influence of anthropogenic impact on communities of ground-dwelling invertebrates that have been found in other studies. It is possible that a finer resolution of taxa may highlight a unique pattern of macroinvertebrate use of wombat mounds.

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