Physical Sciences and Mathematics Commons^™

Modeling Intake Of Grazing Cows Fed Complementary Feeds, D R. Buckmaster, L A. Holden, L D. Muller, R H. Mohtar

IGC Proceedings (1997-2023)

A model suitable for predicting intake for grazing or non-grazing dairy cows is presented. The model integrates the potentially intake limiting factors of physical fill, physiological energy demand, wet mass, herbage availability, herbage cover, and grazing time. Integration of these factors with a simple set of linear ration balancing constraints yields a model suitable for predicting supplemental feed requirements as well as potential animal production from a grazed land. The model is semi-theoretical, being descriptive in structure, but containing empirical relationships.

Modeling The Biomass Production Of Grasslands Of Wallonia According To Their Functional Type, U. Kokah Essomandan, D. Knoden, B. Dumont, J. Bindelle

IGC Proceedings (1997-2023)

Permanent grasslands are complex ecosystems which respond with a great variability - in terms of specific richness - to soil type and management strategies. Modelling is a valuable tool to explore these relationships. Our work consisted in adapting the Moorepark St Gilles grass growth model (MoSt GG) designed to model Lolium perenne plant functional type (PFT) pastures (PFT A) to a different PFT (Dactylis glomerata, PFT B) through literature-based parametrization. The model was evaluated under Walloon (Belgium) conditions using growth trials from 2014 to 2018 in two sites with contrasting pedo-climatic conditions. Three to five cuts were performed …

Modelling Basal Area Of Perennial Grasses In Australian Semi-Arid Wooded Grasslands, S. G. Marsden, K. C. Hodgkinson

IGC Proceedings (1997-2023)

In many semi-arid pastoral systems, landscape processes easily become dysfunctional. Shifts to less functional states may be irreversible, and have long-term consequences for pastoral profitability and social viability of rural communities. Typically, shifts to lower functional states involve a decline in perennial grasses (Hodgkinson, 1994). Here we develop a conceptual basis for modelling the basal area of perennial grasses in a semi-arid grassland and validate the model using data from a 10-year grazing study.

A Systems Approach To Assessing The Viability Of Grazing Legume Systems Across Europe, C. F. E. Topp, C. J. Smith, L. Wu, G. Molle

IGC Proceedings (1997-2023)

Forage legumes are important in grassland farming throughout much of the world because of their ability to fix atmospheric nitrogen, and hence they are expected to play an increasingly prominent role in low- input grazing farming systems in Europe. Nevertheless, the socio-economic impact of the adoption of the "new" legume based grazing technologies have been poorly researched (Rochon et al., 2004). Thus a methodology has been developed to:

* Assess the on-farm costs and benefits of including different legume crops for animal production;
* Determine the types of management systems and environmental conditions under which forage legumes may play …

Modelling Tiller Density Dynamics In A Grass Sward, Masahiko Hirata

IGC Proceedings (1997-2023)

Simulation models are useful tools for grassland management. Among many quantitative and qualitative attributes describing vegetation of grasslands, density of plant population is important because of its close relationship with persistence of grasslands (Hirata, 2004), which in turn is crucial for sustainable agricultural production and/or conservation of the environment, wildlife and recreational resource. Although various models have described grassland vegetation, relatively few models have dealt with plant population density. This paper presents a model describing dynamics in tiller population density in a grass sward.

Modelling Winter Grass Growth And Senescence, D. Hennessy, S. Laidlaw, M. O'Donovan, P. French

IGC Proceedings (1997-2023)

In temperate climates, because net grass growth in winter is low, most grass growth models deal with the main growing season (Mar-Oct in the N Hemisphere), with little emphasis on grass growth in winter (Nov-Feb). However, grass tissue turns over continuously (Hennessy et al., 2004) and the fate of herbage entering the winter is important in extended grazing season systems. This study aimed to model winter grass growth for the period 15 Oct 2001 to 28 Jan 2002 for a range of autumn closing dates (1 Sep, 20 Sep and 10 Oct) by modifying an existing model, so that …

Grasscheck: Monitoring And Predicting Grass Production In Northern Ireland, P. D. Barrett, A. S. Laidlaw

IGC Proceedings (1997-2023)

Grass budgeting is a key management practice on dairy farms to balance grass supply on paddocks with grass demand by the grazing herd. Grass budgets must be pre-emptive to be effective. The uncertainty of grass production and the difficulty in quantifying both current and forecasted rates of growth hamper effective budgeting and paddock management. Grass growth rates are highly variable both in time and space. Therefore, they vary greatly between locations at any given time and also across the season at any given location. Figure 1 shows the pattern of growth rates recorded at the Agricultural Research Institute of Northern …

A Simple Theoretical Model For Calculating Agricultural Value Of Grasslands, G. Nagy

IGC Proceedings (1997-2023)

In spite of the emerging new social demands for non-material grassland products and services (nature reservation, environmental protection, landscape and amenity), the productivity of grasslands is going to remain in the mainstream of overall grassland use in many regions and countries of the world. Strategic planning of future grassland use in a region needs reliable information on the agricultural value of grasslands. The purpose of our research programme was to find a model for calculating the agricultural value of grasslands, in order to assist the classification of grassland productivity for a given area.

Decision Support System For Grassland-Based Sheep Production In The Chilean Patagonia, R. R. Vera, S. Morales, C. Aguilar

IGC Proceedings (1997-2023)

Temporal decision-making in sheep production systems of the Chilean Patagonia is influenced by forage availability in existing paddocks, which in turn is determined by previous use, localisation, climate and soil. Also, production strategies are evolving, with a trend towards fat lamb production, introduction of new breeds and a reduction in the importance of wool production. The objective of this study was to develop an initial version of a spatial empirical simulation model based on extremely limited information, to predict forage growth and sheep production so that decision-makers can assess alternative production strategies.

Comparison Of Methodological Tools In Tropical Soil Carbon Sequestration Field Research, Bram Van Putten, M. C. Amézquita

IGC Proceedings (1997-2023)

Models play a crucial role in studying complex systems like soil Carbon sequestration processes (Hanson et al., 2001). A Carbon sequestration research project is currently under way in pasture and silvopastoral systems of four Tropical American ecosystems. A main research question is the identification of Land Management Systems (LMS) that exhibit optimal soil Carbon sequestration capacity (identification question). Another main issue is the extrapolation of data in space and time (extrapolation question).

Modelling Winter Grass Growth And Senescence, D. Hennessy, S. Laidlaw, M. O'Donovan, P. French

IGC Proceedings (1997-2023)

In temperate climates, because net grass growth in winter is low, most grass growth models deal with the main growing season (Mar-Oct in the N Hemisphere), with little emphasis on grass growth in winter (Nov-Feb). However, grass tissue turns over continuously (Hennessy et al., 2004) and the fate of herbage entering the winter is important in extended grazing season systems. This study aimed to model winter grass growth for the period 15 Oct 2001 to 28 Jan 2002 for a range of autumn closing dates (1 Sep, 20 Sep and 10 Oct) by modifying an existing model, so that …

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.

Grasscheck: Monitoring And Predicting Grass Production In Northern Ireland, P. D. Barrett, A. S. Laidlaw

IGC Proceedings (1997-2023)

No abstract provided.

Modelling Of Herbage Intake And Milk Production By Grazing Dairy Cows, Rémy Delagarde, M. O'Donovan

IGC Proceedings (1997-2023)

Key-points

1. Models predicting intake and performance of grazing ruminants from animal, sward, grazing and supplements characteristics are rare, but they are now included in several decision support systems (DSS).

2. An evaluation of the performance and accuracy of published models are rarely undertaken by their authors, but this is proposed in this paper.

3. There is still a need for experimental research but also for the development of generic and dynamic models to predict intake and performance over a wide range of grazing conditions.

Data Curation For Modeling Tall Fescue Biomass Dynamics With Dssat-Csm, M. B. Hanson, P. D. Alderman, T. J. Butler, A. Caldeira Rocateli

IGC Proceedings (1997-2023)

While models for predicting forage production are available to aid management decisions for some forage crops, there is limited research for a yield model designed specifically for tall fescue (Schedonorus arundinaceus). Therefore, our objective was to adapt an existing perennial forage model, the Decision Support System for Agrotechnology Transfer Cropping Systems Model (DSSAT-CSM) for predicting forage biomass of tall fescue in the southern Great Plains. To evaluate model performance, there must first be a high level of data manipulation and cleaning. In this project, a cohesive dataset combining biomass, weather, soil, and management data were structured into DSSAT …

Crop Updates 2008 - Farming Systems, John De Majnik, Paul Meibusch, Vince Logan, Louise Barton, Wahid Biswas, Daniel Carter, Nicolyn Short, Jodie Bowling, Glen Riethmuller, James Fisher, Moin Salam, Stephen Davies, Jim Dixon, Dennis Van Gool, Alison Slade, Bob Gilkes, Megan Abrahams, Caroline Peek, Daniel Gardiner, Kari-Lee Falconer, David Hall, Jeromy Lemon, Harvey Jones, Yvette Oliver, Tania Butler, Michael Robertson, Stephen Carr, Chris Gazey, David York, Joel Andrews, Michael Simeoni, G. Peter Mangano, Svetlana Micic, Dave Gartner, Adam Clune, Matthew Morell, Adam Umbers, Angelo Loi, Brad Nutt, Clinton Revell, Geoff Kew, Vivien Vanstone, Ali Bhatti, Ming Pei You, Imma Farre, Bill Bowden, Henry Smolinski, Jane Speijers, John Bruce, David Mccarthy, Gary Lang, David Rees, Rob Grima, John Young, Ross Kingwell, Chris Oldham, Derk Bakker, Ian Foster, David Beard, Wen Chen, Richard Bell, Ross Brennan, Art Diggle, Reg Lunt, Qifu Ma, Zed Rengel, Tim Hilder, Dusty Severtson, Shahajahan Miyan, Sam Clune, Barb Sage, Tenielle Martin, Chris Newman, Neal Dalgliesh, Caroline Peak, Andrew Blake, Megan Ryan, Richard Bennett, Tim Colmer, Daniel Real, Jiyan Pang, Lori Kroiss, Dion Nicol, Tammy Edmonds-Tibbett, Ron Mctaggart, Sean Kelly, Helen Hunter

Crop Updates

This session covers thirty nine papers from different authors:

PLENARY

1. Developments in grain end use, Dr John de Majnik, New Grain Products, GRDC, Mr Paul Meibusch, New Farm Products and Services, GRDC, Mr Vince Logan, New Products Executive Manager, GRDC

PRESENTATIONS

2. Global warming potential of wheat production in Western Australia: A life cycle assessment, Louise Barton1, Wahid Biswas2 and Daniel Carter3, 1School of Earth & Geographical Sciences, The University of Western Australia, 2Centre of Excellence in Cleaner Production, Division of Science and Engineering, Curtin University of Technology, 3Department of Agriculture and …

Crop Updates 2005 - Farming Systems, David Stephens, Nicola Telcik, Ross Kingwell, Wayne Pluske, Bill Bowden, Mike Collins, Frances Hoyle, D. V. Murphy, N. Milton, M. Osman, L. K. Abbott, W. R. Cookson, S. Darmawanto, Bill Crabtree, Geoff Anderson, Darren Kidson, Ross Brennan, Nick Drew, Craig Scanlan, Lisa Sherriff, Bob French, Reg Lunt, Jeff Russell, Angie Roe, Ian Maling, Matthew Adams, George Yan, Mohammad Hamza, Glen Riethmuller, Wal Anderson, Angela Loi, Phil Nichols, Clinton Revell, David Ferris, Phil Ward, Andrea Hills, Sally-Anne Penny, David Hall, Michael Robertson, Don Gaydon, Tress Walmsley, Caroline Peek, Megan Abrahams, Paul Raper, Richard O'Donnell, Trevor Lacey, Meredith Fairbanks, David Tennant, Cameron Weeks, Richard Quinlan, Alexandra Edward, Chris Carter, Doug Hamilton, Peter Tozer, Renaye Horne, Tracey Gianatti, Paul Carmody, Ian Foster, Michele John, Ross George, Imma Farré, Ian Kininmonth, Dennis Van Gool, Neil Coles, Bill Porter, Louise Barton, Richard Harper, Peter Ritson, Tony Beck, Chris Mitchell, Michael Hill, Fiona Barker-Reid, Will Gates, Ken Wilson, Rob Baigent, Ian Galbally, Mick Meyer, Ian Weeks, Traci Griffin, D. Rodriguez, M. Probust, M. Meyers, D. Chen, A. Bennett, W. Strong, R. Nussey, I Galbally, M. Howden

Crop Updates

This session covers forty four papers from different authors:

PLENARY

1. 2005 Outlook, David Stephens and Nicola Telcik, Department of Agriculture

FERTILITY AND NUTRITION

2. The effect of higher nitrogen fertiliser prices on rotation and fertiliser strategies in cropping systems, Ross Kingwell, Department of Agriculture and University of Western Australia

3. Stubble management: The short and long term implications for crop nutrition and soil fertility, Wayne Pluske, Nutrient Management Systems and Bill Bowden, Department of Agriculture

4. Stubble management: The pros and cons of different methods, Bill Bowden, Department of Agriculture, Western Australia and Mike Collins, …

Crop Updates 2004 - Cereals, Wal Anderson, Vivian Vanstone, Robert Loughman, Vanessa Stewart, Darshan Sharma, Christine Zaicou-Kunesch, Brenda Shackley, Mohammad Amjad, Steve Penny Jr, Glen Riethmuller, Jeromy Lemon, Mario D'Antuono, Veronika Reck, Ben Curtis, Judith Devenish, Melaine Kupsch, Anne Smith, Blakely Paynter, Roslyn Jetter, Leanne Schulz, Jocelyn Ball, Tom Sweeny, Stephen Loss, Ashleigh Brooks, Justin Fuery, Geoff Anderson, Zed Rengel, Paul Damon, Eddy Pol, Narelle Hill, Ray Tugwell, Ron Mctaggart, Nathan Moyes, John Majewski, Manisha Shanker, James Piotrowski, Ciara Beard, Kithsiri Jayasena, Kazue Tanaka, Grey Poulish, Debbie Thackray, Rohan Prince, Roger Jones, Peter Nelson, Nigel Metz, Leisa Armstrong, Yee Leong (Alex) Yung, Moin Salam, David Tennant

Crop Updates

This session covers twenty eight papers from different authors:

PLENARY

1. Declining profitability in continuous cropping systems. Is more wheat the answer on Duplex soil? Dr Wal Anderson, Department of Agriculture

2. Disease implications of extending the wheat phase in low-medium rainfall areas, Dr Vivian Vanstone and Dr Robert Loughman, Department of Agriculture

3. Prolonged wheat phase on duplex soils – where do weeds set the boundary? Vanessa Stewart, Department of Agriculture

WHEAT AGRONOMY

4. Management of small grain screenings in wheat, Dr Wal Anderson and Dr Darshan Sharma, Department of Agriculture

5. Agronomic responses of new wheat varieties, Christine …