Modeling impacts and adaptations of climate change on soybean (Glycine max) production in Himachal Pradesh, India

Soybean [Glycine max (L.) Merr.], one of the commercial crops grown under rainfed conditions in Himachal Pradesh produced low yields due to uneven weather conditions. This study presents outcome of a simulation study to evaluate the impact of projected climate change on yields of soybean and simulated adaptations in the face of climate change. During past three decades the region has experienced increase in temperature and decrease in rainfall. The validated InfoCrop model runs for 20 years (1989-2008) to assess impacts of the projected climate change on soybean production. The Root Mean Square Error (RMSE) values were 8.8 days and 190.4 kg/ha for days to maturity and crop yield between simulated and observed yields of five years (2004-08) under two sowing environments. The elevated levels of 50 and 100 parts per million (ppm) carbon dioxide (CO2) increased soybean yield by 5.0 to 10.2%. The projected yield losses due to elevated levels of temperature by 1 and 2oC alone ranged between 1.3 to 3.5 and 4.5 to 6.0 percent respectively, for all planting windows. The elevated temperature of 1oC coupled with 50 ppm elevated level of carbon dioxide (420ppm) showed increase in yield up to 4.9 percent with shortened average growing period up to 2 days. The further rise of temperature to 2oC with 50 ppm elevated level of carbon dioxide caused increase in simulated yield up to 2.3 percent in simulations of 1989-2008 compared to control conditions. Similarly, 100 ppm elevated level of carbon dioxide with 1oC rise in temperature caused increase in yield between 8.8 to 10.2 percent in all planting windows whereas it was 3.1 to 3.9 percent lesser in 2oC rise in temperature with 100 ppm elevated level of carbon dioxide with compared to 1oC rise in temperature. The climatic grid of 10 percent reduction in rainfall from recent decade 1998-2008 showed small decrease in yield but yield increase of 5.2 to 8.5 percent was observed when coupled with 50 ppm elevated carbon dioxide and 1oC rise in temperature. Hence rise of temperature with elevated carbon dioxide in general increase the yield in region.