Source DocumentPrevious PageTable Of ContentsNext Page

Using local case studies in the high rainfall zone of south-eastern Australia to generate grower confidence in computer model outputs

Angela Clough1 , Penny Riffkin2, Muhuddin Anwar3 and Garry O’Leary3

1 Department of Primary Industries, 402 Mair St, Ballarat, Vic 3350. Email
Department of Primary Industries, Mount Napier Rd, Hamilton, Vic 3300. Email
Department of Primary Industries, Natimuk Road, Horsham, Vic 3401. Email garry.o’,


Grain growers, agronomists and researchers from Tasmania, South Australia and Victoria attended three workshops to identify limitations to achieving yield potential in the HRZ of south-eastern Australia. At these workshops, participants proposed strategies which may improve grain yields using current cultivars. Seven of these strategies were selected for field based case studies. The case studies are now being conducted with at least two case studies are being conducted in each State. Four case studies are in commercial crops and three case studies are utilising existing research field trials. Soil and climatic data will be collected from each study site and other strategy specific data will be collected as required following established protocols before the start of the 2008 winter growing season. Data from each case study will be used within the APSIM Model Version 6.0. Model outputs will be compared with the case study data. An alignment between model and field outputs will provide growers with confidence in using models as tools in making management decisions. This may help to improve production and profitability for growers in the HRZ.

Key Words

wheat, models


The high rainfall zone of southern Australia (HRZ) is defined as the area with an annual rainfall between 500 mm and 900 mm and is in the temperate climate zone (mild or warm summer and cold winter). The HRZ has been identified as having the potential to produce higher wheat, barley, pulse and canola grain yields than are achieved with current cultivars and management practices (Sylvester-Bradley pers. comm., Gardner et al 1983, Riffkin et al 2007). Research has identified that the current available cultivars are disparate from the ideotype best suited to the HRZ and this has been communicated to plant breeders (Riffkin et al in press a,b). Improvements in grain yields through breeding more appropriate cultivars will take several years.

A more immediate means of improving grain yields in the HRZ is to tailor management practices so they maximise grain yield potential of the current cultivars. Crop models can be used to trial different management practices in a way that poses no economic risk to grain growers. Outputs from models run over a range of different seasons based upon historical meteorological data, can be reported in terms of a probability of modeled practices achieving higher grain yields or gross margins than current field practices.

Several crop models have been developed that should be useful in the HRZ. However they must first be accepted by grain growers as a valid alternative to field trials if they are to be of any use in facilitating practice change. This project is using a participatory approach to build grain grower confidence in crop models by testing selected crop models with local data from broadacre grain crops and plot-based research cereal trials.

Participatory Approach

Workshops with grain growers

Workshops were conducted in South Australia, Tasmania and Victoria, organised by the local branches of the farmer group Southern Farming Systems. New management practices with potential in each State were identified by grain grower participants. Grain growers also identified two or three locations within each State that they considered to be representative of local soil, climate or cropping system. Outcomes of these workshops provided the foundation of the field based case studies to increase grower confidence in crop models.

Site selection

Local farmer groups were engaged to assist with site selection. The farmer groups agreed that broadacre sites should be used for the validation exercise if possible as grain growers may have more confidence in results produced in standard farming conditions. Site selection followed the criteria set out in the Project Protocols document (Clough and Riffkin, unpublished). Principle selection criteria was that each site must have had a uniform cropping treatment for the last 3 years, be in a region identified to be of interest by participants at the workshops and be able to accommodate a management practice identified during the workshops as being of interest to local grain growers.

Data collection

Management of each case study site is being conducted as set out in the Project Protocols document to ensure sufficient and appropriate data are obtained to run APSIM Model Version 6.0 and that data collection is consistent at all sites. The Project Protocols document is freely available to all participating grain growers. Site data that has been collected are : soil chemical and physical characteristics, drained lower limit and drained upper limit, slope and stubble load. Site specific soil data will be made available to each grain grower. Fifty years of climate data including rainfall, solar radiation and maximum and minimum temperatures are being sourced from the Bureau of Meteorology as actual or interpolated data. On-farm rainfall data for 2008 is being collected either using automatic on-site weather stations or manually by the grain grower. Agronomic data listed for collection in the Project Protocols document are : crop type, cultivar, date of 50% emergence, above ground biomass (AGB) at GS31, date of 50% flowering and the date that the crop is ready to harvest (GS 93). The following crop management data is also listed for collection : sowing date, seeding rate, seed dressing used (rate and type), row spacing, seeding depth, chemical applications (rate, type and date), harvest date and general crop observations (eg incidence of waterlogging, insect damage or weather damage). The last three year’s paddock history detailing crop management actions and crop outcomes will be sought from each grower. At this stage, sowing date, crop cultivar, date of 50% emergence and AGB at GS31 data has been collected.

Case study details

Seven sites were selected within the HRZ; two in Tasmania (Symmons Plains and Campbell Town), two in South Australia (Frances and Conmurra) and three in Victoria (Meredith, Mininera and Dunkeld). These corresponded with locations within the HRZ selected by grain growers at the workshops. Both the South Australian sites are research trial plots established as part of a water use efficiency (WUE) project. The site at Symmons Plains is part of a stubble management project with 400 m2 plots and the site at Campbell Town is in at a paddock scale managed with broadacre equipment. The Meredith and Mininera sites are both in broadacre paddocks managed with grain growers’ normal cropping practices. The Dunkeld site is research plots on raised beds sown with a cone seeder and managed using small scale equipment.

Conmurra and Frances have the same case studies with a time of sowing (TOS) trial and a WUE trial using a winter wheat, a spring wheat and Gairdner barley. The Symmons Plains case study is a stubble management trial overlaid with a +/- grazing treatment sown to Mckellar winter wheat after a faba bean crop. The Campbell Town case study consists of two sowing rates x two nitrogen rates sown to Gairdner barley. Treatments at Meredith are a split paddock with two wheat varieties; Rudd and Bolac sown into newly renovated raised beds after a canola crop. The treatments at Mininera are a split paddock with two wheat varieties Kellalac and Bolac sown into a standing canola stubble. The treatments at Dunkeld are a split paddock sown to Bolac wheat with two fertiliser input regimes; district practice and high fertiliser inputs aimed at attaining 10 t/ha grain yield.


The case studies are a form of participatory research. Grain growers have participated in all stages of the model validation process to date with enthusiasm. The diversity of environments, rotations and treatments will enable several crop models to be validated under local conditions with actual and modelled results presented to grain growers in 2009. Ensuring consistent and timely data collection across three States has been a challenge, however, having a standard Project Protocols documents has provided a reliable framework for all participants.


Clough A. and Riffkin P.A. (2008, unpublished). Protocols for On-farm case studies 2008. p14.

Gardner W.K. , Velthuis R.G., and Amor R.L. (1983). Field crop production in south-west Victoria. 1 Area description, current land use and potential for crop production. Journal Australian Institute of Agricultural Science 50, 60-70.

Riffkin P.A., Potter, T. and Clough A (2007). Plant characteristics suited to higher canola yields in the High Rainfall Zone of southern Australia. In: Proceedings of the 15th Australian Research Assembly on Brassicas Geraldton, WA pp 109-112.

Riffkin P.A., Potter, T. and Clough A (in press a) The Model Canola Plant for the High Rainfall Zone. DPI Victoria

Riffkin P.A., Brand, J. and Clough A (in press b) The Model Pulse Plant for the High Rainfall Zone. DPI Victoria

Previous PageTop Of PageNext Page