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Modelling cropping systems to ensure greater water use and water use efficiency

Fillery, I.R.R. Dr; Ph: (08) 9333 6681; Fax: (08) 9387 8991; i.fillery@ccmar.csiro.au

Asseng, S. Dr; Ph: (08) 9333 6615; Fax: (08) 9387 8991; s.asseng@ccmar.csiro.au

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

Sponsor: GRDC, Grains Research and Development Corporation

Objectives:

1. To use computer simulation to establish the relationships between water and nitrogen use efficiency and management options in wheat production.

2. To quantify crop growth, water and N dynamics for model justification.

3. To use computer simulation for risk analysis to determine appropriate strategies for optimising biomass production and final grain yield.

Methodology:

The APSIM wheat model was used to evaluate the effect of Mediterranean environments on wheat growth and the limitations to crop production associated with deep sandy soils with limited water-holding capacity, and duplex soils with a range of physical and chemical limitations. Field measurements of crop growth and soil water dynamics from previous studies and in new field experiments were used for model justification. The APSIM wheat model was tested against several data sets which describe wheat growth at Moora (deep sand), East Beverley (duplex soil), Wongan Hills (deep sandy soil) and Merredin (duplex soil).

Progress:

The APSIM wheat model was extensively tested by comparing predicted crop growth, grain yield, soil water dynamics, mineral N in soil and N uptake by wheat with observed values. In total, the model was tested using about 4000 observations obtained from 44 data sets collected at 4 locations (three soil types) in Western Australia. Overall, the model performance has been acceptable. However, the routines that calculate protein % in grain required improvement. Root growth in waterlogged duplex soils was poorly simulated and studies were conducted to obtain a better understanding of the effect of waterlogging on root growth. New routines were added to the APSIM wheat model to simulate the changes in the depth of perched water tables in duplex soils following rainfall, and aeration deficit effects on root and shoot growth.

Computer simulation was used to define the relationships between water and nitrogen use efficiency, and sowing dates, crop development rates, N-supply. Risk analysis was undertaken to determine appropriate strategies for optimising biomass production and final grain yield in relation to historic rainfall patterns. Finally, the APSIM wheat model was used to assist the extrapolation of results from season and site specific agronomic experiments, and to assess the risk of economic loss associated with the adoption of management practices aimed at optimising grain yield.

Period: starting date 1993-07; completion date 1997-06

Status: completed

Keywords: wheat; cropping systems; crop management; water use efficiency; Nitrogen; crop yield; simulation models; APSIM wheat

Publications:

Anderson, G.C., Fillery, I.R.P., Dolling, P.J., and Asseng, S. (1998). Nitrogen and water flows for pasture-ley and lupin-wheat rotations in deep sands. I. Nitrogen mineralisation and utilisation. Australian Journal of Agricultural Research 49, 329-343.

Anderson, G.C., Fillery, I.R.P., Dunin, F.X., Dolling, P.J., and Asseng, S. (1998). Nitrogen and water flows for pasture-ley and lupin-wheat rotations in deep sands. II. Water drainage and nitrate leaching. Australian Journal of Agricultural Research 49, 345-361.

Asseng, S., Fillery, I.R.P. and Gregory, P.J. (1998). Wheat response to alternative crops on a duplex soil. Australian Journal Experimental Agriculture 38, 481-488.

Asseng, S., Keating, B.A. and Fillery, I.R.P. (1995). Wheat crop simulation in a Mediterranean Environment on a duplex soil. Proceedings of the International Congress on Modelling and Simulation, November 27-30, 1995, Newcastle. 2, pp. 62-67.

Asseng, S., Keating, B.A., Huth, N.I. and Eastham, J. (1997). Simulation of Perched Watertables in a Duplex Soil. In Proceedings of the International Conference on Simulation and Modelling MODSIM97, Hobart, December 1997.

Asseng, S., Fillery, I.R.P., Anderson, G.C., Dolling, P.J., Dunin, F.X. and Keating, B.A. (1998). Use of the APSIM wheat model to predict yield, drainage, and NO3 leaching for a deep sand. Australian Journal of Agricultural Research 49, 363-377.

Asseng, S., Keating, B.A., Gregory, P.J., Fillery, I.P.R., Bowden, J.W., Turner, N.C., Palta, J.A., and Abrecht, D.G. (1998). Performance of the APSIM wheat model in Western Australia. Field Crops Research 57, 163-179.

 

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