Performance of the apsim-wheat model in western australia

#PERFORMANCE OF THE APSIM WHEAT MODEL IN WESTERN AUSTRALIA DRIVER#

Keywords: potential yield, plant-available water capacity, model, water-use efficiency, APSIM.

Crop and Pasture Science CSIRO Publishing 2.Modern Information Technology and Education Center, Lanzhou Jiaotong University, Lanzhou 730070, China 3.College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China Received: Revised: Online: Published: RichHTML 1.

The improved method gave more realistic estimates of water-limited potential yield, particularly at low and high rainfall and on soils of low PAWC. With the addition of a variable intercept (dependent upon GSR), accounting for stored soil water at the start of the season and placing a cap on GSR that is a function of the soil PAWC, the predictive performance (RMSE 624 kg/ha) was similar to that gained with the daily time-step model APSIM (RMSE 419 kg/ha). Significant improvements to the F&S were achieved with a few simple adjustments. The original F&S method overestimated actual yields, particularly at high rainfall (GSR > 220 mm) when PAWC was low, and underestimated yields at low rainfall (GSR < 220 mm). Proceedings of MODSIM 97, International Congress on Modelling and Simulation, Hobart, Tasmania, Australia, 811 December 1997. The water-limited potential yields predicted from these methods were compared with simulations from the daily time-step simulation model APSIM and observed wheat yields from 146 dryland wheat crops, managed to water-limited potential yield, covering the 1996вЂ“2006 seasons in the Mediterranean-type growing environments of Australia. To derive a simple yet accurate method for estimating potential yield, several adjustments to F&S were evaluated: ( 1 ) accounting for stored soil water at sowing, ( 2 ) varying the value of the intercept between yield and growing-season rainfall (GSR), ( 3 ) varying the water-use efficiency of the crops (WUE) according to soil type, and ( 4 ) adjustments to GSR depending on soil plant-available water capacity (PAWC). More complex models are available to predict potential yield more accurately however, farmers and advisors favour easy-to-use-methods to estimate potential yield. The model predicted biomass of summer crops and.

Rainfall-based empirically derived models such as that proposed by French and Schultz (1984) (F&S) can be used to determine an upper limit of water-limited potential yield, but F&S often overestimates actual yield as it does not account for rainfall distribution, runoff, drainage, or stored soil water. The APSIM model, which has been evaluated extensively against field measurements in various other studies, was tested again to gain further confidence in using it for these investigations, by using data from a one-year summer crop (fallow, millet or cowpea)-winter wheat cropping system experiment.

#PERFORMANCE OF THE APSIM WHEAT MODEL IN WESTERN AUSTRALIA DRIVER#

Rainfall is the main driver of potential yield in the dryland cropping environment of Australia. However, specific simulation studies to predict biomass, yield, drainage and nitrate leaching are now possible for wheat crops on the tested soil types and rainfall zones in Western Australia.Improving estimates of water-limited yield of wheat by accounting for soil type and within-season rainfall Improving estimates of water-limited yield of wheat by accounting for soil type and within-season. Asseng S, Keating B A, Fillery I R P, Gregory P J, Bowden J W, Turner N C, Palta J A and Abrecht D G 1998b Performance of the APSIM-wheat model in Western Australia Field Crops Res. In particular, grain protein tended to be overpredicted at high protein levels and underpredicted at low levels. Simulation of grain protein, and depth to the perched water table showed limited accuracy when compared with field measurements.

The wheat crops were generally sown between May and June, shortly after the break of the season. Yields tended to be underestimated during terminal droughts due to insufficient pre-anthesis stored carbohydrates being remobilised to the grain. Performance of the APSIM-wheat model for Western AustraliaSimulations using the APSIM-wheat model have been compared against 3500 actual measured values. Grain yields were well predicted with a coefficient of determination r 2(1:1)=0.77, despite some underestimation during severe terminal droughts. The overall APSIM model predictions of shoot growth, root depth, water and N uptake, soil water, soil N, drainage and nitrate leaching were found to be acceptable. The field experiments covered 10 seasons, with variations in sowing date, plant density, N fertiliser, deep ripping and irrigation. Model outputs were compared with detailed field experiments from four rainfall zones, three soil types, and five wheat genotypes. The model was used to simulate above- and belowground growth, grain yield, water and N uptake, and soil water and soil N in wheat crops in Western Australia. APSIM-wheat is a crop system simulation model, consisting of modules that incorporate aspects of soil water, nitrogen (N), residues, and crop development.

Performance of the apsim-wheat model in western australia