вЂProceedings of the 10th Australian Agronomy ConferenceвЂ™. (2001) Improving the reliability of sorghum production in the farming system. Agronomy Journal 68,В 111вЂ“116.Д«utler GJ, Cawthray S, Castor M, Yeates S, Christian T (1976 ) Improved water-use efficiency in dryland grain sorghum by promoted plant competition. The decision on what row configuration to use should be made tactically and requires consideration of the starting soil water, the soilвЂ™s plant-available water capacity (PAWC), and the farm familyвЂ™s current attitude to risk. Skip configurations reduce the chance of total failure by capping the yield potential, which in turn reduces the long-term average yield. To achieve the higher average yield in the solid configuration the producer suffers some total failures.

Skip configurations limit the yield potential as a safeguard against crop failure. This difference in average yield is a result of the solid configuration having a higher yield potential compared with the skip configurations. Over the long term, the production of sorghum in a solid configuration produced a higher average yield compared with sorghum produced in a skip configuration. These simulations showed a trade-off between long-term average production (profitability) and annual yield reliability (risk of failure this year). Long-term simulation runs using long-term weather files for locations near the experimental sites were used to determine the value of skip row sorghum production as a means of maintaining yield reliability. These measurements underpinned changes to the APSIM-Sorghum model so that it accounted for the elliptical water uptake pattern below the crop row and the reduced total light interception associated with skip row configurations. This paper describes modifications made to the APSIM sorghum module to account for the difference in water usage and light interception between alternative crop planting configurations, and then demonstrates how this new model can be used to quantify the long-term benefits of skip sorghum production.Дetailed measurements of light interception and water extraction from sorghum crops grown in solid, single and double skip row configurations were collected from on-farm experiments in southern Qld and northern NSW.

APSIM and SAMARA as more mechanistic crop models, have a higher sensitivity of the adjustment of key parameters, notably the specific leaf area for APSIM in low PPS varieties, while SAMARA shows a higher response to parameters changes for high PPS varieties.In recent years, many sorghum producers in the more marginal (<600 mm annual rainfall) cropping areas of Queensland and northern New South Wales have used skip row configurations in an attempt to improve yield reliability and reduce sorghum production risk. Based on detailed field observations, this study showed that crop models captured well the phenology and leaf development of the photoperiod sensitive (PPS) varieties of West Africa, but failed to estimate accurately partitioning of assimilates during grain filling. The predictions using APSIM were found to be closest to the observed followed by DSSAT and Samara models respectively. Prediction of grain yield and biomass was less accurate for both calibration and validation. Samara estimates were found to be the closet with the lowest RMSE values (<3 leaves for TLN and <1.0В m 2/m 2 for LAI) followed by DSSAT and APSIM respectively. Across the varieties, there was over-estimation for simulated leaf area index (LAI) while total leaf number (TLN) fitted well with the observed values. With the exception of highly sensitive variety (IS15401), APSIM and Samara estimates indicate the lowest value of RMSE (<7days) against the observed values for phenology events (flowering and maturity) compared to DSSAT model. Simulated phenology and morphology organs during calibration and validation were within the closet range of measured values with the evaluation of model error statistics (RMSE and R 2). Our results confirmed the capability of each selected model to reproduce growth and development for varieties of diverse sensitivities to photoperiod. In this study, we compared the performance of three process-based crop models (APSIM, DSSAT and Samara) for prediction of diverse sorghum germplasm having widely varying photoperiod sensitivity (PPS) using detailed growth and development observations from field trials conducted in West Africa semi-arid region. In particular, crop models are key tools to assess the growth and development of such varieties against climate and soil variability.

Moench) varieties of West Africa into the local cropping system might help to improve the resilience of food production in the region. Better defining niches for the photoperiod sensitive sorghum (S orghum bicolor L.

Apsim sorghum