Huth N.I.,CSIRO |
Huth N.I.,Agricultural Production Systems Research Unit |
Thorburn P.J.,CSIRO |
Radford B.J.,LMB |
Agriculture, Ecosystems and Environment | Year: 2010
There is increasing focus on greenhouse gas emissions from agricultural systems. One suggested method for increasing the sequestration of carbon (C) within agricultural soils is to increase crop productivity and therefore C input into the soil. However, if enhanced production is achieved via nitrogenous fertilisers, there is a potential tradeoff between decreased C emissions and increased nitrous oxide (N2O) emissions due to the increased soil C and nitrogen (N). An alternative is to incorporate leguminous crops into cereal cropping rotations to provide a biological source of N. However, the likely production of N2O from N released during the decomposition of leguminous residues is unknown as is the impact on C input into the soil when some cereal crops are replaced with grain legumes. Consequently, an analysis of the likely impacts has been undertaken for a subtropical dryland cropping system in Queensland, Australia where soil, climate and management are conducive to denitrification losses. A series of scenarios embracing a range of cropping rotations, N fertilisers and leguminous crops was tested using the Agricultural Production Systems Simulator (APSIM). The model configuration was tested using long term data from the Brigalow Catchment Study site near Theodore, Queensland, Australia (24.81°S, 149.80°E). A wide range of data was used in testing the model for the major terms in the C, N and water balances. Scenario analyses of alternative management systems including the use of fertiliser or legume grain or forage crops within cereal rotations demonstrated that soil C can be managed to some degree via simple changes in agronomic practice. The use of legumes within cereal rotations was not always as effective in reducing N2O emissions as improved fertiliser practice. For example, replacing wheat with chickpea did not reduce N2O emission relative to fertilised systems and did not assist in increasing soil C due to impacts on stubble cover over the important summer months. The fact that some interventions proved counterproductive due to complex feedback mechanisms highlights the need for detailed models which capture the links between water, C, N and management. Crown Copyright © 2010.
Agency: European Commission | Branch: FP7 | Program: JTI-CS | Phase: JTI-CS-2013-1-SGO-02-051 | Award Amount: 576.12K | Year: 2014
In all-electrical aircrafts, the corresponding electrical ram air fan should be optimized in order to improve its current design in two aspects: a)generate pressure drop at low flows without surge issues; b)cooling of the fan electrical motor at high inlet air temperatures. The ECS control logics produces two main typical operating points, one with high flow when the ram-air fan creates enough flow to cool both the ECS main heat exchanger and the ECS motor stator, and the second when it only needs to provide a low airflow for the latter necessity. As the pressure drop is similar in both situations but the flow very different, this creates surge problems that should be eliminated for adequate operation. Meanwhile, the fact that the ram-air fan is located downstream the ECS main heat exchanger implies that the air inlet arrives to the fan at high temperatures, what difficulties its own correct electrical motor cooling, both from a mechanical and electrical points of view. Considering these objectives, a new fan concept will be selected from available bibliographic and consortium expertise, and designed using the consortium skills in deep fundamental fluid mechanics and heat transfer knowledge (Technical University of Catalonia - UPC ), advanced CFD tools and aerodynamic know-how (Termo Fluids - TF) and engineering capacities of a fan manufacturer (LMB SAS). The proposed design related to surge problem will be implemented in a prototype and tested accordingly. In a similar manner, a solution for electrical motor cooling will be found.The final solution must also consider its impact on the whole ECS pack, in order to maintain its global performance objectives.
Radford B.J.,LMB |
International Journal of Energy, Environment and Economics | Year: 2011
A long-term tillage experiment was designed to assess the effect of tillage frequency and intensity on rainfed grain production and quality in the semi-arid subtropical environment of central Queensland, Australia. There were four tillage treatments: traditional tillage (TT), stubble mulch tillage (SM), reduced tillage (RT) and no till (NT), each with and without applied fertiliser (N+Zn). On completion, after 20 years of treatment application, all treatments were managed using no till and appropriate fertiliser (N+Zn) application for a further 7 years. During the 20 years when tillage treatments were being applied, the reduced tillage treatments (NT, RT and SM) outyielded TT in 10 of 22 crops grown. Mean yields without fertiliser were 2.0 t/ha (TT) and 2.6 t/ha (NT) while mean yields with fertiliser were 1.9 t/ha (TT) and 2.9 t/ha (NT). During the next 5 years of across-the-site no till with fertiliser, the former reduced tillage treatments outyielded the former TT in each of the 5 crops grown. For example, the long-term NT gave an average yield of 3.3 t/ha while the short-term NT, formerly TT for 20 years, produced only 2.1 t/ha - a 57% yield increase for the long-term no-till. This increase was due to both increased soil water storage and higher water use efficiency (WUE). Both were attributed to the development of improved soil structure, higher population densities of soil macrofauna and slightly higher soil organic carbon content. High WUE in NT was also attributed to a beneficial effect resulting from slow early growth under no till. Results indicate it takes at least 20 years to attain the full soil benefits (physical, chemical and biological) of a no-till system. The large yield responses from the three reduced tillage treatments, during and after treatment application, were realised in part because cropping frequency exceeded the appropriate level for traditional tillage. Increased cropping frequency also results in higher levels of groundcover, which reduces soil erosion and creates a more sustainable fanning system. A high-yielding, viable cropping system can also contribute towards environmental sustainability by reducing the need for further land clearing. © 2011 Nova Science Publishers, Inc.
Yates C.J.,LMB |
Gibson N.,LMB |
Pettit N.E.,LMB |
Pettit N.E.,University of Western Australia |
And 2 more authors.
Australian Journal of Botany | Year: 2011
We investigated the ecological relationships, reproductive biology and demography of four shrub taxa restricted to ironstone ranges in south-western Australia, to assess the feasibility of post-mining reintroductions. We found that three taxa were restricted to narrow fissures in massive ironstone and the fourth was restricted to fissures and skeletal soils over ironstone. In all taxa, adult plants were the most abundant life stage in populations and produced seeds annually. Newly emerged seedlings were observed in low numbers each winter of three census years, with the highest rates occurring when winter rainfall was above average in the semiarid Mediterranean climate. Mortality was highest and most variable for 1-year-old seedlings (50-93%), 1-year-old seedlings (17-67%), juveniles (21-54%) and vegetative adults (6-50%), and was lowest and least variable for the reproductive adults (2-7%). The restriction of three of our study taxa to narrow fissures excludes the option of using seedlings in reintroductions. Using seeds, although possible, will be both an inefficient and a high-risk strategy for at least three of the four taxa studied. This is because of the low frequency of years when winter rainfall is sufficient to stimulate high rates of seed germination, coupled with the consistently high rates of seedling mortality in most years, and no easy method for determining which rock fissures will be suitable for plant establishment. The more widespread taxa showed reproductive and demographic characteristics similar to those of the taxa restricted to the narrow fissures, indicating that establishment of many species will be difficult in this environment. © 2011 CSIRO.
Barrett S.,South Coast Region |
Austral Ecology | Year: 2015
Throughout the world, mountains provide unique environments with attendant endemic species. In the otherwise subdued landscapes of the floristically diverse Southwest Western Australian Floristic Region, the Stirling Range provides the region's only distinctly montane environments. On the highest peaks of the Range the characteristic heathland (Kwongan) of the region becomes a dense shrub thicket with many endemic species and is known as the Eastern Stirling Range Montane Heath and Thicket. We assessed the conservation status of the Montane Heath and Thicket using the IUCN Red list criteria for ecosystems. We found the ecosystem to be Critically Endangered based on its naturally limited geographic extent and area of occupancy in combination with the impacts of the plant pathogen Phytophthora cinnamomi. Historical sources and long-term monitoring were critical to our assessment of this ecosystem highlighting their importance in detecting and understanding likely causes of change. The ecosystem is predicted to decline further in the absence of intensive management due to current threatening processes as well as the potential future impacts of climate change. The Montane Heath and Thicket, while substantially modified still retains areas with highly significant conservation values and these pose many challenges for management. Continued management of P.cinnamomi through phosphite application and management of fire return intervals will be critical to conserve the remaining areas of the thicket where sensitive plant species occur together with an ex situ conservation program including ongoing seed collection and translocation for the most threatened species. © 2014 Ecological Society of Australia.
Gibson N.,LMB |
Yates C.,LMB |
Byrne M.,LMB |
Langley M.,LMB |
Australian Journal of Botany | Year: 2012
Calothamnus quadrifidus subsp. teretifolius A.S.George N.Gibson is a short-range endemic shrub whose habitat has been greatly reduced by clearing for agriculture. Reproductive output was high in all populations sampled, although there were large differences among populations in fruit set, the number of seeds per fruit and seed germination. These traits showed no relationship to population size, degree of isolation, or fragment size, which contrasts strongly with the patterns found in a widespread congener. Demographic studies in remnants with an intact understorey showed stable adult populations with continuous seedling recruitment. In contrast, there was consistent widespread failure of seedling and juvenile recruitment in degraded roadside remnants that also showed significant mortality of reproductive adults. In these degraded remnants, recruitment failure appears to be the primary cause of species decline. © 2012 CSIRO.