Simulation Modelling of Alternative Strategies for Adaptation of Sorghum to Climate Change in North-Western New South Wales

Abstract

In the short term climate change scenario to 2030, it has been suggested that farmers could exploit existing strategies developed to cope with the variable climate in the summer rainfall cropping zone of north-eastern Australia. These strategies include: varying crop residues at sowing; varying plant population; varying row configuration; changing the sowing window; and varying the crop duration. This paper reports the results of APSIM simulations of sorghum yields and economic analysis based on stochastic weather generation downscaled CSIRO Mk 3.5 projections for 2030, 2060 and 2090. Two sites were chosen for the analysis: Quirindi representing cooler higher rainfall conditions and Moree representing warmer lower rainfall conditions. By 2030 maximum and minimum temperatures are projected to rise by 1.6-1.7°C and rainfall to decrease by 10-11% at Quirindi and Moree. Some of the climate change adaptation options favoured by farmers did not deliver the expected results. These included reducing planting density, skip row configurations, early planting and quicker maturing varieties at both Quirindi and Moree. For Quirindi the best strategy to maximise sorghum yields and returns in 2030 is to plant a medium maturity variety in November-December at 5-7 plants/m² in a solid row configuration with maximum crop residue retention. The result for Moree was similar except that October and December plantings were better than November. Gross margin budgets were used to estimate individual crop profitability under the different scenarios. When additional modelling is undertaken to include rotation crops such as wheat, barley and chickpeas, whole-farm economic case studies will be used to identify optimum business strategies under different climate change scenarios. We plan to engage farmers in Participatory Action Research to identify strategies for optimum choices of crop species and sequences to cope with climate variability and climate change.