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Poulton P.L.,CSIRO | Dalgliesh N.P.,CSIRO | Vang S.,CARDI Cambodian Agricultural Research and Development Institute | Roth C.H.,CSIRO
Field Crops Research | Year: 2016

Rice production is the major source of food security in Cambodia where 85% of the total arable land is cultivated to rice with traditional transplanted medium and later maturity varieties accounting for >70% of the plantings during the monsoon period. Climate change poses risks and opportunities to the sustained productivity of rice based farming systems in Cambodia. The objective of this study is to evaluate adaptation strategies that support the replacement of traditional low input systems with a ‘response’ farming approach for better temporal utilisation of available labour, land and water resources. Options include replacing a traditional transplanted crop with short duration varieties, more efficient crop establishment methods and better agronomic and fertiliser management that responds to timing, intensity and longevity of the monsoon and has potential to mitigate effects of current and future climate variability. To achieve this, we apply the APSIM farming systems model to evaluate how adaptation options for smallholder farmers can increase or maintain overall productivity within present day climate variability and future climates, using downscaled GCM baseline and 2030 climate scenarios. To extend beyond the 2030 climate change scenarios, we also assess production risk from an increase in ambient air temperature of 1.4–4.3 °C, atmospheric CO2 concentration of 545–885 ppm and variation in rainfall, for rainfed and irrigated systems to 2090. Modelled scenarios indicate a yield response to elevated CO2 of 17.5% at a concentration of 680 ppm for current temperature and rainfall and are consistent with established physiological effects of CO2 on crop yields. In response to temperature, yields decreased by 4% per degree increase from an average annual baseline temperature of 28 °C. Adaptation strategies involving deployment of short duration rice varieties, in conjunction with direct seeding and better N management, indicate comparable and improved production can be achieved to 2030 under likely future climate projections. However, beyond 2030, the distribution and timing of rainfall has a significant influence on rainfed lowland rice in Cambodia. In this case a more transformational approach involving widespread provision of irrigation water will be required to offset climate change impacts. © 2016 Elsevier B.V.

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