Physical Sciences and Mathematics Commons^™

Using Cuticular Wax Alkanes And Computer Simulation To Estimate Diet Selection, Herbage Intake And Nutrient Cycling In Grazing Sheep, H Dove, R J. Simpson

IGC Proceedings (1997-2023)

In grazing ewes, plant cuticular wax alkanes were used as markers to estimate diet selection, herbage intake, N intake and N excretion in faeces. Pasture and animal data were then used as inputs to the decision-support system GrazFeed, which simulates grazing and digestion to predict herbage intake, N intake and N excretion. Estimated and predicted intakes agreed closely, especially for N intake, and it is concluded that, subject to further investigation of the possibility that GrazFeed slightly under-estimated faecal N excretion, the close agreement between estimated and predicted OM and N intakes suggests that this combined use of alkane methods …

Modelling Leucaena Biomass Under Rainfed Production Systems Of Semiarid Regions, M. J. D. Cândido, J. L. G. Santos, A. C. R. Cavalcante, S. R. Maranhão, M. A. Santos, J. M. Osorio Leyton

IGC Proceedings (1997-2023)

The climatic variability of semiarid regions is the main source of uncertainties associated with forage and animal production, indicating a need for tools that accurately estimate forage production in order to construct a forage budgeting plan for livestock. This study simulated the biomass of Leucaena (Leucaena leucocephala) using the PHYGROW model in four locations located in Brazilian Semiarid. The work was carried out based on field data collected from 2019 to 2021. After sowing in 2018, leucaena was harvested when it reached 200 cm and to a target residual height of 70 cm. The biomass (fresh matter) was …

Integrating Climatological-Hydrodynamic Modeling And Paleohurricane Records To Assess Storm Surge Risk, Amirhosein Begmohammadi, Christine Y. Blackshaw, Ning Lin, Avantika Gori, Elizabeth Wallace, Kerry Emanuel, Jeffrey P. Donnelly

OES Faculty Publications

Sediment cores from blue holes have emerged as a promising tool for extending the record of long-term tropical cyclone (TC) activity. However, interpreting this archive is challenging because storm surge depends on many parameters including TC intensity, track, and size. In this study, we use climatological-hydrodynamic modeling to interpret paleohurricane sediment records between 1851 and 2016 and assess the storm surge risk for Long Island in The Bahamas. As the historical TC data from 1988 to 2016 is too limited to estimate the surge risk for this area, we use historical event attribution in paleorecords paired with synthetic storm modeling …

Linking Community And Ecosystem Ecology By Developing A Grassland Ecosystem Model (Gemini) With Interactions Between Plant, Herbivore And Soil Microbial Populations, Jean-François Soussana, S. Witzmann, P. Loiseau, S. Fontaine, Pascal Carrère, Catherine Picon-Cochard, F. Louault

IGC Proceedings (1997-2023)

Simulation models may help to understand the functional role of plant and soil biodiversity for C and N cycles and for intake by herbivores in semi-natural grassland ecosystems. Detailed models of grassland ecosystems calculate C, N, water and energy fluxes without accounting for the species dynamics in the plant and soil communities. Schwinning & Parsons (1996) proposed a simple pasture growth model that includes mixed grass and clover components. This model was, however, restricted to 2 plant functional groups and it excluded the dynamics of the soil organic matter. The role of competitive interactions between at least 2 functionally distinct …

Development Of A Model Simulating The Impact Of Management Strategies On Production From Beef Cattle Farming Systems Based On Permanent Pasture, M. Jouven, R. Baumont

IGC Proceedings (1997-2023)

Grazing systems in Europe increasingly have to meet environmental objectives, which influence management strategies. A deterministic model describing farming system dynamics is being developed in order to elucidate interactions between nature-friendly management practices, as for example late (after flowering) hay harvest or moderate stocking rate, and agricultural output.

Enhancing Grasslands Education With Decision Support Tools, Helen G. Daily, J. M. Scott, J. M. Reid

IGC Proceedings (1997-2023)

We have successfully used Decision Support Tools (DST) relevant to the management of grazing enterprises to enhance problem solving skills of undergraduates in Australia. Tools such as GrassGro^tm (Moore et al., 1997) and GrazFeed^tm (Freer et al., 1997) are accessed from a central server by authorised users at many widely dispersed Universities across Australia using remote access to thin-client technology via an Internet portal. This has been supplemented with training for lecturers. Experience in developing appropriate teaching and learning materials and the reliable delivery of simulation software to many clients has enhanced learning outcomes at tertiary …

Systems Simulation Assists Land Capability Estimation In Australia’S Temperate Grasslands, Richard J. Simpson, L. Salmon, P. Graham, A. D. Moore, A. Stefanski, D. J. Marshall, J. R. Donnelly

IGC Proceedings (1997-2023)

Intensification of production in the water-limited grasslands of temperate Australia has increased the need to quantify their sustainable carrying capacity. Empirical rainfall-based rules for estimating stocking rate fail when used in districts with differing weather patterns, or when soil and pasture resources limit the utilisation of rainfall. Grazing systems simulation should help to overcome these problems because local conditions can be taken into account. This study investigated the impact of soil resources on potential stocking rate, profitability and production risk in a local climatic area of the southern tablelands of NSW, Australia.

Evaluating The Economic And Environmental Sustainability Of Integrated Farming Systems, C. A. Rotz, M. A. Sanderson, M. Wachendorf, F. Taube

IGC Proceedings (1997-2023)

Economic and environmental sustainability has become a major concern for forage-based animal production in Europe, North America and other parts of the world. Development of more sustainable farming systems requires an assimilation of experimental and modelling research. Field research is critical for supporting the development and evaluation of models, and modelling is needed to integrate farm components for predicting the long-term effects and interactions resulting from farm management changes. Experimentally supported simulation provides a tool for evaluating and comparing farming strategies and predicting their effect on the watershed, region and beyond.

Development Of A Model Simulating The Impact Of Management Strategies On Production From Beef Cattle Farming Systems Based On Permanent Pasture, M. Jouven, R. Baumont

IGC Proceedings (1997-2023)

Grazing systems in Europe increasingly have to meet environmental objectives, which influence management strategies. A deterministic model describing farming system dynamics is being developed in order to elucidate interactions between nature-friendly management practices, as for example late (after flowering) hay harvest or moderate stocking rate, and agricultural output.

A New Agro-Meteorological Simulation Model For Predicting Daily Grass Growth Rates Across Ireland, R. P. O. Schulte

IGC Proceedings (1997-2023)

Grass growth rates and herbage yields depend on weather conditions, soil characteristics and grassland management and differ from year to year and from site to site. In the past, grass growth has been predicted using both mechanistic and statistical models. The accuracy of mechanistic models is commonly insufficient for practical application, while statistical models generally apply to one test site only (e.g. Han et al., 2003). In this paper a semi-empirical grass growth model is presented which is numerically accurate, but which can be applied to contrasting sites across Ireland at the same time.

Enhancing Grasslands Education With Decision Support Tools, H. G. Daily, J. M. Scott, J. M. Reid

IGC Proceedings (1997-2023)

We have successfully used Decision Support Tools (DST) relevant to the management of grazing enterprises to enhance problem solving skills of undergraduates in Australia. Tools such as GrassGro™ (Moore et al., 1997) and GrazFeed™ (Freer et al., 1997) are accessed from a central server by authorised users at many widely dispersed Universities across Australia using remote access to thin-client technology via an Internet portal. This has been supplemented with training for lecturers. Experience in developing appropriate teaching and learning materials and the reliable delivery of simulation software to many clients has enhanced learning outcomes at tertiary level. We …

Using The Grassgro Decision Support Tool To Evaluate The Response In Grazing Systems To Pasture Legume Or A Grass Cultivar With Improved Nutritive Value, H. Dove, J. R. Donnelly

IGC Proceedings (1997-2023)

Decision support tools (DST) based on models of grazing systems allow the evaluation of changes in enterprise management on productivity and profitability. The Grassgro DST (Moore et al., 1997) uses historical weather data on a daily time step to simulate pasture growth and the resultant productivity of either grazing sheep or cattle. Different pasture species are represented within a parameter set that describes the response of pasture species to their environment. Manipulation of these parameters provides a means of evaluating, a priori, the likely responses of livestock production to ‘improved cultivars’. We report the results of simulations conducted …

Pasture Land Management System Decision Support Software, G. E. Groover, S. R. Smith, N. D. Stone, J. J. Venuto, J. M. Galbraith

IGC Proceedings (1997-2023)

Controlled or rotational grazing provides benefits to producers and society through profitable and sound management of grazing land and livestock. Pasture land management system (PLMS) is a decision support system developed to help university, government, and professionals provide technical pasture management assistance to beef and dairy producers. The PLMS focuses on the balance between seasonal forage supply and nutrient demand in a dairy or beef cattle operation. It allows users to explore and compare alternatives (dividing fields into multiple paddocks, changing stocking rates, and forage species) through a visual display and embedded simulation. Users enter a description of the farm …

Grass Growth Modelling: To Increase Understanding And Aid Decision Making On-Farm, P. D. Barrett, A. S. Laidlaw

IGC Proceedings (1997-2023)

Key points

1. Crop and grass growth models have been developed over the last 50 years, or so, but general appreciation of their benefits and potential has been recognised only relatively recently. The most popular application of grass growth models has traditionally been for knowledge understanding.

2. There is growing awareness of the potential of models in decision support systems (DSS) applications to aid pasture management and grassland budgeting on dairy farms.

3. Although some models have been developed for DSS, their widespread uptake in industry has been slow; challenges still exist which need to be addressed in order to improve their precision …

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Formation Of Permafrost And Its Influence On Natural Gas Hydrate Accumulation In Muli Region, Qinghai Province, Wang Liping, Zhu Yinghao, Li Ning, Xu Shuanhai, Tian Yanzhe, Liu Naifei, Wang Wenli

Coal Geology & Exploration

The characteristics of the existing permafrost and natural gas hydrates were summarized and analyzed by studying the natural gas hydrate formation in Muli Region, Qinghai Province. On the basis of the evidence of the Quaternary climate survey and the available geological exploration data on the Qinghai-Tibet Plateau, FLAC^3D was used to simulate and calculate the formation of permafrost. The calculation results show that the existing permafrost probably formed during the late Holocene Neoglacial(4 000-3 000 to 1 000 a BP), and a stable boundary at bottom of the permafrost layer formed after about 170 a of cooling at a …

Adoption And Influence: Industry Evaluation Of The GrassgroTm Decision Support Tool, E. M. Salmon, A. D. Moore

IGC Proceedings (1997-2023)

The GrassGro Decision Support tool (DS tool) (Donnelly and Moore, 1999) was released for commercial use in Australia with a training package in late 1997. An assessment of its adoption was made by a survey of 53 registered users in March 1999. An evaluation of the software and training package was made at training workshops by 92 users between 1997 and December 1999. The response rates to the survey and the evaluation were 62% and 82% respectively. Seventy six percent of survey respondents had analysed at least one problem with GrassGro and 27% had applied GrassGro to five or more …

Overview On Gplates: Focus On Plate Reconstruction, Shatavisa Chatterjee, Soumyajit Mukherjee

Turkish Journal of Earth Sciences

Plate tectonic reconstructions have been employed in geosciences since 1970s, in the context of hydrocarbon exploration, regional geology and paleobiology. Such studies have given valuable inputs for climate and geodynamic computations, present-day mantle structure, models of plate motion, and the interpretation of the drift of hotspots, true polar wander (TPW), sea level and stratigraphic signals. However, geodynamic models generated in the past by incorporating global plate tectonic reconstructions have limitations. To overcome this, GPlates software brings forward a new era of interactive plate tectonic reconstruction software integrated with GIS databases that incorporates a wide variety of geological and geophysical data. …

The Role Of Forages In Sustainable Cropping Systems Of Southern Australia, William D. Bellotti

IGC Proceedings (1997-2023)

The historical context, recent trends, and possible future role of forages in cropping systems are reviewed. Three recent themes will be developed: 1) The successful exploitation of genetic diversity resulting in commercial development of new legume species as pasture cultivars with specific traits better suited to the needs of current farming systems. 2) Improved understanding of key soil processes under grazed pastures, particularly soil water and soil nitrogen, and how these processes impact on indicators of sustainability like deep drainage and nitrate leaching. 3) An emerging capacity for predicting the effect of pasture-crop sequences on soil processes, crop growth and …

Simulation Of Alternative Plans For Community Based Goat Breeding Program In Arid, Semi-Arid And Mixed Production Systems In Ethiopia, T. Jembere, Barbara Rischkowsky, T. Dessie, K. Kebede, A. Okeyo Mwai, T. Mirkena, A. Haile

IGC Proceedings (1997-2023)

On station small ruminant researches in Ethiopia were ineffective due to various factors. As alternative, community based breeding program (CBBP) has emerged. In the current CBBPs, sire side selection only (SN1) is practiced. The objective of the present work was to compare SN1 by simulating alternative breeding scenarios for Abergelle (AB), Centeral Highland (CH) and Woyto-Guji (WG) goat breeds in Ethiopia. Three scenarios including selection on dam side (SN2) in addition to SN1, application of genomic selection (SN3) onto SN1 and use of sires from SN1 for mating in additional flocks (SN4) were simulated and compared with SN1 based on …

Simulation Of Alfalfa Production With Epic, L. Chun, X. Xin, H. Tang

IGC Proceedings (1997-2023)

No abstract provided.

Integrating Dual‐Purpose Wheat Crops Into Different Sheep Production Systems In Southern Australia: Impacts On Livestock, Economic Returns And Risk, Andrew D. Moore, H. Dove, W. M. Kelman

IGC Proceedings (1997-2023)

No abstract provided.

Ever Graze‐Prime Lamb Production On Perennial Based Grasslands In Southwest Australia, Paul Sanford, J. Ryan, P. Jakobsson, E. Dobbe, E. Mccready

IGC Proceedings (1997-2023)

No abstract provided.

Pasture Growth Forecasts For Temperate Regions In Southeastern Australia, Brendan R. Cullen, Richard J. Eckard, I. R. Johnson

IGC Proceedings (1997-2023)

No abstract provided.

Modeling Holocene Peatland Carbon Accumulation In North America, Qianlai Zhuang, Sirui Wang, Bailu Zhao, Filipe Aires, Catherine Prigent, Zicheng Yu, Jason K. Keller, Scott Bridgham

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Peatlands are a large carbon reservoir. Yet the quantification of their carbon stock still has a large uncertainty due to lacking observational data and well‐tested peatland biogeochemistry models. Here, a process‐based peatland model was calibrated using long‐term peat carbon accumulation data at multiple sites in North America. The model was then applied to quantify the peat carbon accumulation rates and stocks within North America over the last 12,000 years. We estimated that 85–174 Pg carbon was accumulated in North American peatlands over the study period including 0.37–0.76 Pg carbon in subtropical peatlands. During the period from 10,000 to 8,000 years …

Role Of Fluid Injection On Earthquake Size In Dynamic Rupture Simulations On Rough Faults, Jeremy Maurer, Eric M. Dunham, Paul Segall

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

An outstanding question for induced seismicity is whether the volume of injected fluid and/or the spatial extent of the resulting pore pressure and stress perturbations limit rupture size. We simulate ruptures with and without injection‐induced pore pressure perturbations, using 2‐D dynamic rupture simulations on rough faults. Ruptures are not necessarily limited by pressure perturbations when (1) background shear stress is above a critical value, or (2) pore pressure is high. Both conditions depend on fault roughness. Stress heterogeneity from fault roughness primarily determines where ruptures stop; pore pressure has a secondary effect. Ruptures may be limited by fluid volume or …

Dynamics And Impacts Of The May 8th, 1902 Pyroclastic Current At Mount Pelée (Martinique): New Insights From Numerical Modeling, Valentin Gueugneau, Karim Kelfoun, Sylvain J. Charbonnier, Aurelie Germa, Guillaume Carazzo

School of Geosciences Faculty and Staff Publications

The Mount Pelée May 8th, 1902 eruption is responsible for the deaths of more than 29,000 people, as well as the nearly-complete destruction of the city of Saint Pierre by a single pyroclastic current, and is, sadly, the deadliest eruption of the 20th century. Despite intensive field studies on the associated deposit, two conflicting interpretations of the pyroclastic current dynamics (either a blast or a simple ash-cloud surge) emerged in the 90’s and have been paralyzing research ever since, leaving numerous unknowns (i.e., source conditions, volume). This study is the first to investigate numerically the May 8th, 1902 pyroclastic …

Economic Review Of Pasture Development Options For North Australian Beef Enterprises, Neil D. Macleod, Dianne Mayberry, Lindsay Bell, Ian Watson

IGC Proceedings (1997-2023)

Beef cattle grazing (~14 million head) native pastures is the dominant economic use of northern grazing lands (2.3 million km2). Few enterprises make positive economic returns in most years or achieve the necessary productivity gains (~2% per annum) to offset an ongoing cost-price squeeze (McCosker et al., 2010). A significant contributor to poor performance is low reproductive performance, management of first calving heifers, calf growth and weaning rates and liveweight gain - linked to nutrition and the low quality of pastures. Pasture development technologies (Gramshaw and Walker, 1988) are available but uptake has been poor. Three pasture development options …

Improved Modelling Of Lucerne (Medicago Sativa L.) Production For Grazing Livestock, Andrew Smith

IGC Proceedings (1997-2023)

Lucerne (or alfalfa; Medicago sativa L.)-based pastures play an important role in livestock and mixed farms (croplivestock) in Australia. If lucerne is to be more widely adopted, it will be important that landholders are able to plan to maximize its benefits to their livestock enterprises (usually as a part of a diverse feed base), as well as assess the benefits and minimizing the costs of lucerne phases to subsequent crops. However, the ability to accurately model lucerne plant physiology across the full spectrum of environments, genotypes and cultivars remains elusive. This study aimed to review and revise the description of …

Modelling Complex Sheep Systems Using Ausfarm, Susan M. Robertson, Michael A. Friend

IGC Proceedings (1997-2023)

Simulation modelling can be a valuable method for extrapolating experimental findings to different weather or management conditions. However, most of the decision support tools which are available for sheep grazing systems, for example GrassGro® (Donnelly et al. 1997), are limited to modelling of relatively simple sheep management. This makes validation of simulations against experimental results difficult where management changes from year to year, and where more complex sheep management is used. This study evaluated the use of the AusFarm® decision support tool (Moore et al. 2007) to model a split-joined sheep system, using different ram breeds against experimental …

Analysis On Influence Of Ground Transmitting Electrode On Bidirectional Em-Mwd Signal Transmission Based On Ansys, Shao Chun, Han Jian, Chu Zhiwei, Xu Lin

Coal Geology & Exploration

The grounded emitter electrode is a necessary component of the bidirectional EM-MWD signal downlink system, and its reasonable parameter setting can improve the signal downlink effect, but at present, little is known about its influence on the downlink signal. This paper is based on the bi-directional EM-MWD working mechanism, combined with the current field theory, using ANSYS finite element software, establishes a three-dimensional simulation model of bidirectional EM-MWD signals, and analyzes the emission distance, length, diameter and resistivity of the ground transmitting electrode versus the downlink signal. The simulation results show that the downlink signal reception effect is positively correlated …