Contributions of soil and crop factors to plant available soil water capacity of annual crops on Black and Grey Vertosols

Improved methods for field measurements of plant available soil water capacity (PAWC) of Black and Grey Vertosols in Australia’s north-eastern grain region were employed to characterise 83 soil–crop combinations over 7 depth intervals to 180 cm. Soil sub-order was shown to influence all components of PAWC (means of 224 and 182 mm in Black and Grey Vertosols, respectively) with drained upper limit (DUL), bulk density (BD), and crop lower limits (CLL) showing clear separation between soil sub-orders and a trend with soil depth. In addition to soil sub-order and soil depth effects, CLL showed crop effects such that expected PAWC of various crops when adjusted for soil sub-orders were: cotton 240 mm; wheat 233 mm; sorghum 225 mm; fababean 209 mm; chickpea 197 mm; barley 191 mm; and mungbean 130 mm. A total of 549 measured CLL values were used to develop a predictive model for estimating CLL from the soil sub-order, depth, DUL, and crop by predicting a CLL as a function of DUL and a depth-dependent variable for each crop–soil sub-order. The model CLL = DUL * (a + b * DUL) explained 85% of observed variation in the measured data with no significant bias between observed and predicted data. While properly measured data would be more reliable than estimated data, where specific site accuracy is less critical, this model may be used to estimate PAWC with an acceptable degree of accuracy

Inhibition of metal dusting using thermal spray coatings and laser treatment

Alloy 600 and Alloy 800H are susceptible to metal dusting. Both alloys were thermally sprayed with two different corrosion resistant coatings: Ni50Cr and Ni31Cr11Al0.6Y. Laser remelting was used to enhance further the effectiveness of these coatings to resist metal dusting by eliminating interconnected porosity and improving coating adhesion. Uncoated, coated and laser-treated coated samples of Alloy 600 and Alloy 800H were exposed to a mixed gas atmosphere (20% H2, 80% CO at 650°C). Samples were examined in plan and cross-section using optical and scanning electron microscopy, electron probe microanalysis and X-ray diffraction. The extent of carbon deposition was tracked by mass difference measurements at intervals during exposure. The thermally sprayed coatings enhanced metal dusting resistance by acting as physical barriers to carbon ingress. The NiCrAlY coating performed well on both substrates. The NiCr coating itself underwent metal dusting and spalled from Alloy 800H due partly to CTE mis-match stresses. Laser treatment of both coatings successfully eliminated interconnected porosity and hence enhanced metal dusting resistance

Inhibition of metal dusting of alloy 800H by laser surface melting

Metal dusting is a catastrophic carburisation phenomenon that occurs at temperatures of 450-850°C in atmospheres of high carbon activity. The resistance of alloys to corrosion, including metal dusting, relies on the formation of a dense, adherent oxide layer that separates the alloy from the corrosive environment. For such an oxide layer to be protective, it must achieve full surface coverage, be crack-free and be established before significant material degradation has occurred. Formation of a protective oxide scale can be enhanced by increasing the population of rapid diffusion paths for the protective elements (e.g. Cr and Al) to reach the alloy surface. In this work, laser surface melting has been used to improve the metal dusting resistance of Alloy 800H by creating a rapid solidification microstructure and, thereby, increasing the density of rapid diffusion paths. Oxidation during laser processing has been found to be detrimental to metal dusting resistance. However, it has been demonstrated that the resulting oxide can be removed without compromising metal dusting resistance. Results of exposure to a metal dusting atmosphere (20% H2 80% CO at 650°C) are presented. Samples have been examined in plan and cross-section using optical and scanning electron microscopy. Selected samples were also examined by electron probe microanalysis and X-ray diffraction

Governing through representatives of the community: A case study on farmer organizations in rural Australia

The concept ‘governing through the community’ has been used frequently to interpret the neoliberal policy embraced by Australian governments since the 1990s. Yet explanation is still inadequate of how ‘governing through the community’ is conducted in practice, particularly the specific mechanisms that regulate interaction among government agencies, groups seeking to represent the community and individuals in the community. In this study, we find that ‘governing through the community’ is actually ‘governing through representatives of the community’ because it is the representatives that make the community visible and governable. This observation is based on a case study of three kinds of farmer organizations, in two states of Australia, who see their role as serving the community and are regarded by outsiders as representatives of the community at least on certain issues. An understanding of the interaction among different stakeholders within and outside of the community is developed through three themes of ‘paperwork’, ‘data’ and ‘price’ that were used by locals from Landcare groups, grower groups and farmer cooperatives, respectively, to articulate how they experience the mechanisms through which their interactions are regulated. This paper concludes that these groups can claim to represent some residents within a defined geographical area, rather than any exact definition of ‘the community’ and that this is a sufficient claim to enable these groups to participate in the process of ‘governing through the community’. The tensions between government agencies, community representatives and community members threaten the legitimacy of the community representatives as intermediaries. Government agencies do try to contribute to reduce these tensions by strengthening the legitimacy of community representatives through various policy and project mechanisms. However, while the stated aim of ‘governing through the community’ is often focused on producing a ‘flourishing rural community’ through improving democratic modes of representation, this study demonstrates that it is only part of the community, namely the ‘targeted customers’ of the farmer organizations, that is potentially reachable to ‘the state’

The FARMSCAPE approach to farming systems research

Abstract From six years of participatory action research has emerged Farmers', Advisers' and Researchers' Monitoring, Simulation. Communication And Performance Evaluation (FARMSCAPE) as an approach for supporting farmers' management of dryland crop production. In contrast to the strategy of producing decision support software for farmers, FARMSCAPE features simulation-aided discussions about management among farmers, advisers, and (sometimes) researchers. The key is a capability to flexibly simulate the consequences of a wide range of crop and cropland management alternatives in a variable climate at a paddock scale using local soil and weather data. The high level of interest among farmers has led to a current focus on transfer of the technology to agricultural service providers. Keywords: Farming systems, on-farm, simulation, soil monitoring, action research The term "farming systems research" is most commonly used in Australia to mean "research on bio-physical sub-systems aimed at improving systems of farming". Research methodology tends to be a flexible and pragmatic use of formal experimental design and statistical analysis. Experiments are designed to represent aspects of farming sufficiently realistically for results to be meaningful to farmers and advisers but without unnecessarily or overly straining professional standards for methodology concerning making valid comparisons with adequate confidence. In the interest of the former, experiments are often located on commercial farms, and, increasingly, with farmers. A second established way of interpreting the term "farming systems research" is "systems research which is about farming". Here the emphasis is the application to farming of systems concepts and methodologies that have evolved over the past 50 years, mainly outside agriculture. This paradigm has been termed "systems agriculture" (1). Emphasis here is on approaches to learning/ research/ intervention when the system under study does not lend itself readily to scientific experimentation. Feasibility of the latter declines with increases in scale and/or, complexity and temporal variability. Two pools of methodological resources for addressing such systems are available—often termed "hard" and "soft" approaches. "Hard" systems approaches have, at their core, mathematical models of the systems of interest designed to represent the essential aspects of function in relation to environment. But the hard lesson in the main stream of the hard systems movement has been that the approach turns out to be appropriate only to those aspects of systems that are not complicated by people with purposes and freedom of choice (3). The fact that the specific nature of a farm system substantially reflects the design and management efforts of a farmer means that a "soft" systems approach, eg participative action research, should enhance the usefulness and impact of the research on real farming. McCown, RL; Carberry, PS; Foale, MA; Hochman, Z; Coutts, JA; Dalgliesh, NP (1998) The FARMSCAPE approach to farming systems research Proc. 9th Aust. Agron. Conf., Wagga Wagga (1998) 633-636

Assessing climate risks in rainfed farming using farmer experience, crop calendars and climate analysis

Climate risk assessment in cropping is generally undertaken in a top-down approach using climate records while critical farmer experience is often not accounted for. In the present study, set in south India, farmer experience of climate risk is integrated in a bottom-up participatory approach with climate data analysis. Crop calendars are used as a boundary object to identify and rank climate and weather risks faced by smallhold farmers. A semi-structured survey was conducted with experienced farmers whose income is predominantly from farming. Interviews were based on a crop calendar to indicate the timing of key weather and climate risks. The simple definition of risk as consequence × likelihood was used to establish the impact on yield as consequence and chance of occurrence in a 10-year period as likelihood. Farmers’ risk experience matches well with climate records and risk analysis. Farmers’ rankings of ‘good’ and ‘poor’ seasons also matched up well with their independently reported yield data. On average, a ‘good’ season yield was 1·5–1·65 times higher than a ‘poor’ season. The main risks for paddy rice were excess rains at harvesting and flowering and deficit rains at transplanting. For cotton, farmers identified excess rain at harvest, delayed rains at sowing and excess rain at flowering stages as events that impacted crop yield and quality. The risk assessment elicited from farmers complements climate analysis and provides some indication of thresholds for studies on climate change and seasonal forecasts. The methods and analysis presented in the present study provide an experiential bottom-up perspective and a methodology on farming in a risky rainfed climate. The methods developed in the present study provide a model for end-user engagement by meteorological agencies that strive to better target their climate information delivery

Dialysis Initiation in Patients With Chronic Coronary Disease and Advanced Chronic Kidney Disease in ISCHEMIA-CKD

Background In participants with concomitant chronic coronary disease and advanced chronic kidney disease (CKD), the effect of treatment strategies on the timing of dialysis initiation is not well characterized. Methods and Results In ISCHEMIA-CKD (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches-Chronic Kidney Disease), 777 participants with advanced CKD and moderate or severe ischemia were randomized to either an initial invasive or conservative management strategy. Herein, we compare the proportion of randomized participants with non-dialysis-requiring CKD at baseline (n=362) who initiated dialysis and compare the time to dialysis initiation between invasive versus conservative management arms. Using multivariable Cox regression analysis, we also sought to identify the effect of invasive versus conservative chronic coronary disease management strategies on dialysis initiation. At a median follow-up of 23 months (25th-75th interquartile range, 14-32 months), dialysis was initiated in 18.9% of participants (36/190) in the invasive strategy and 16.9% of participants (29/172) in the conservative strategy (P=0.22). The median time to dialysis initiation was 6.0 months (interquartile range, 3.0-16.0 months) in the invasive group and 18.2 months (interquartile range, 12.2-25.0 months) in the conservative group (P=0.004), with no difference in procedural acute kidney injury rates between the groups (7.8% versus 5.4%; P=0.26). Baseline clinical factors associated with earlier dialysis initiation were lower baseline estimated glomerular filtration rate (hazard ratio [HR] associated with 5-unit decrease, 2.08 [95% CI, 1.72-2.56]; P<0.001), diabetes (HR, 2.30 [95% CI, 1.28-4.13]; P=0.005), hypertension (HR, 7.97 [95% CI, 1.09-58.21]; P=0.041), and Hispanic ethnicity (HR, 2.34 [95% CI, 1.22-4.47]; P=0.010). Conclusions In participants with non-dialysis-requiring CKD in ISCHEMIA-CKD, randomization to an invasive chronic coronary disease management strategy (relative to a conservative chronic coronary disease management strategy) is associated with an accelerated time to initiation of maintenance dialysis for kidney failure.U01 HL117904/HL/NHLBI NIH HHS/United Statesinfo:eu-repo/semantics/publishedVersio

Beyond the plot: technology extrapolation domains for scaling out agronomic science

Open Access Journal; Published online: 14 May 2018Ensuring an adequate food supply in systems that protect environmental quality and conserve natural resources requires productive and resource-efficient cropping systems on existing farmland. Meeting this challenge will be difficult without a robust spatial framework that facilitates rapid evaluation and scaling-out of currently available and emerging technologies. Here we develop a global spatial framework to delineate 'technology extrapolation domains' based on key climate and soil factors that govern crop yields and yield stability in rainfed crop production. The proposed framework adequately represents the spatial pattern of crop yields and stability when evaluated over the data-rich US Corn Belt. It also facilitates evaluation of cropping system performance across continents, which can improve efficiency of agricultural research that seeks to intensify production on existing farmland. Populating this biophysical spatial framework with appropriate socio-economic attributes provides the potential to amplify the return on investments in agricultural research and development by improving the effectiveness of research prioritization and impact assessment

Diagnosis, extent, impacts, and management of subsoil constraints in the northern grains cropping region of Australia

Productivity of grain crops grown under dryland conditions in north-eastern Australia depends on efficient use of rainfall and available soil moisture accumulated in the period preceding sowing. However, adverse subsoil conditions including high salinity, sodicity, nutrient imbalances, acidity, alkalinity, and high concentrations of chloride (Cl) and sodium (Na) in many soils of the region restrict ability of crop roots to access this stored water and nutrients. Planning for sustainable cropping systems requires identification of the most limiting constraint and understanding its interaction with other biophysical factors. We found that the primary effect of complex and variable combinations of subsoil constraints was to increase the crop lower limit (CLL), thereby reducing plant available water. Among chemical subsoil constraints, subsoil Cl concentration was a more effective indicator of reduced water extraction and reduced grain yields than either salinity or sodicity (ESP). Yield penalty due to high subsoil Cl was seasonally variable, with more in-crop rainfall (ICR) resulting in less negative impact. A conceptual model to determine realistic yield potential in the presence of subsoil Cl was developed from a significant positive linear relationship between CLL and subsoil Cl:Since grid sampling of soil to identify distribution of subsoil Cl, both spatially across landscape and within soil profile, is time-consuming and expensive, we found that electromagnetic induction, coupled with yield mapping and remote sensing of vegetation offers potential to rapidly identify possible subsoil Cl at paddock or farm scale.Plant species and cultivars were evaluated for their adaptations to subsoil Cl. Among winter crops, barley and triticale, followed by bread wheat, were more tolerant of high subsoil Cl concentrations than durum wheat. Chickpea and field pea showed a large decrease in yield with increasing subsoil Cl concentrations and were most sensitive of the crops tested. Cultivars of different winter crops showed minor differences in sensitivity to increasing subsoil Cl concentrations. Water extraction potential of oilseed crops was less affected than cereals with increasing levels of subsoil Cl concentrations. Among summer crops, water extraction potential of millet, mungbean, and sesame appears to be more sensitive to subsoil Cl than that of sorghum and maize; however, the differences were significant only to 0.7 m. Among pasture legumes, lucerne was more tolerant to high subsoil Cl concentrations than the others studied.Surface applied gypsum significantly improved wheat grain yield on soils with ESP >6 in surface soil (0–0.10 m). Subsurface applied gypsum at 0.20–0.30 m depth did not affect grain yield in the first year of application; however, there was a significant increase in grain yield in following years. Better subsoil P and Zn partially alleviated negative impact of high subsoil Cl. Potential savings from improved N fertilisation decisions for paddocks with high subsoil Cl are estimated at ~$AU10 million per annum