The effect of climate change on soybean yield in Gorgan

Climate change affects on precipitation and temperature patterns and hence, may alter the crop yeild. This research was conducted to evaluate the effects of climate change on soybean yield in Gorgan using soybean growth simulation model (SSM) under different climatic scenarios. LARS-WG model was used to generate temperature and rainfall data for future period (2013-2042) under emission scenarios of B1, A2 and A1B. The generated and observed weather data for baseline period of (1985-2012) were considered as inputs for a crop-weather model namely, SSM. Various periods of phenology, biological and grain yield for both irrigated and rainfed planting were simulated by defining eight different dates of sowing ranging from the May 11th to 24th July with 10 days interval. Test of significance of means showed an increasing trend in daily maximum and minimum temperature for most of the months and for mean monthly values of rainfall in fewer months. The simulation result of soybean yeild by SSM model indicated that there is no significant difference between initial stages of soybean phenology under impact of emissions scenarios data and observation data but stage length to physiologic and harvest maturity during future periods shorted to 5 days and for late cultivation reached to more than 10 days. Biological and grain yield decreased slightly for irrigated cultivation, and increased for rainfed cultivation in earlier planted crops. Finally, rainfed cropping of soybean is not common in the region, it can be concluded that climate change will not significantly affect on water requirement and yield of soybean in Gorgan region.