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Application of a crop model to examine the efficiency and sustainability of wheat farming in Western Australia

Fillery, I.R.R. Dr; Ph: (08) 9333 6681; Fax: (08) 9387 8991;

Asseng, S. Dr; Ph: (08) 9333 6615; Fax: (08) 9387 8991;

Research organisation: CSIRO Plant Industry, Centre for Mediterranean Agricultural Research , Floreat Park WA 6014

Sponsor: GRDC, Grains Research and Development Corporation


1. To examine the efficiency of use of water and key nutrients in wheat production by applying the APSIM wheat crop model across a range of soil types and climatic zones in Western Australia.

2. To evaluate the effect of combinations of nitrogen application, deep ripping, sowing date and variety on grain yield, drainage and leaching.

3. To develop strategies for ensuring sustainable grain production through improved management of key resources.


The APSIM model will be initialised with data for different soil types and climatic zones. Key model initialisation data including, lower and upper limits for soil water, porosity, density, micro- and macro flow conductivity, organic content, and root growth hospitality information for soil layers, as well as genotype specific parameters for phenology, leaf growth and grain-filling will be assembled. This information will be gathered through collaboration with ongoing GRDC-sponsored field experiments. Soil will be collected from sites where data exists for wheat biomass and grain production, but pertinent soil characterisation and model initialisation data does not exist. Computer simulations will be evaluated against actual measurements before undertaking detailed simulation using long-term weather records.

Historical weather data sets will be provided for all Western Australian weather stations through APSRU. These weather data sets include measured daily rainfall data, measured and calculated maximum and minimum temperature, and calculated solar radiation for the period 1910 to 1991.

Long-term weather data will be used to establish the potential range in wheat production, drainage and nitrate leaching in relation to management options: nitrogen application, deep ripping, sowing date and variety. Management options will be handled separately, or in combination, for each run of the 80-years of simulation. Soil properties will be location specific and will be reset at the start of each year simulation.

Output from simulations will be in the form of probability distributions for grain yield, grain quality, drainage and nitrate leaching in relation to soil type, climatic zone, and management options listed above.


The APSIM wheat model, including a new grain protein routine, has been tested against several data sets generated in Western Australia, New South Wales and from other overseas climatic regions. Results confirmed that the model was able to predict yield, soil water and N dynamics, as well grain protein, for a wide range of conditions. Simulation studies have been conducted using long-term historical weather records to analyse the affect of cultivar, sowing date, N-fertiliser and residue removal on yield, grain protein and drainage in relation to major soil types, rainfall zones and seasons. These results provide a unique set of information to evaluate the potential for profitable and sustainable wheat production. For instance, computer simulations have been conducted with historical long-term weather records to quantify the probability of deep drainage below the root zone, grain yield and grain protein and results were transferred to a geographic information system (GIS). Generated information cover the entire area of a transect (100 km wide) from the coast to the eastern edge of the central wheat belt, including the five major soil types (shallow duplex, deep sand, deep loamy sand, acid deep loam sand and red duplex) that occur in Western Australia. The potential of deep drainage, grain yield and grain protein under current management has been quantified for this transect.

Simulation experiments have shown that management practices that aim to increase production have a high potential to increase yield, but they have minor effects on reducing drainage, in particular in the higher rainfall zones. The model was used to examine the reasons for this outcome.

Period: starting date 1997-07; completion date 2000-06

Status: ongoing

Keywords: wheat; crop yield; water use efficiency; Nitrogen fertilisers; leaching; drainage; models; APSIM wheat


Asseng, S., Ritchie, J.T., Smucker, A.J.M. and Robertson, M.J. (1998). Root growth and water uptake during water deficit and recovering in wheat. Plant and Soil 201, 265-273.

Setter, T.L., Anderson, W.K., Asseng, S. and Barclay, I. (1998). Review of the impact of high shoot carbohydrate concentrations on maintenance of high yields in wheat exposed to environmental stress during grain filling. In Wheat Research Needs Beyond 2000AD, edited by S. Nagarajan, G. Singh, and B.S. Tyagi, Narosa Publishing House, New Delhi, pp. 237-255.

Tennant, D. and Asseng, S. (1997). Probability of drainage from deep sands in Western Australia based on historic weather data and the APSIM model. In Conference Proceedings - Advances in Soil Science for Sustainable Land Use, Geraldton, Western Australia, 30 September - 2 October 1997, pp. 48-52.


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