Climate change impacts assessment and developing adaptation strategies for rainfed foxtail millet in northern Shanxi, China

Climate change is considered to be a serious threat to crop production around the globe. In the northern Shanxi Province of China (SXN), foxtail millet (or millet) is the main crop and generally grows under rainfed conditions. Existing literature has confirmed the millet yield reductions due to climate change in the past. However, little is known about the impacts of future climate change on millet production in the SXN. The main objectives of this study were to investigate the future climate change impacts under two emission scenarios (SSP245 and SSP585) and the potentials of shifting sowing date combined with supplemental irrigation as an adaptation strategy to climate change for millet production in the SXN using the Decision Support System for Agrotechnology Transfer (DSSAT). Two supplemental irrigation strategies were tested: one presowing irrigation only (PSI), and two supplementary irrigations (PSGI) adopting one presowing irrigation and one irrigation during the growing season. We found that the air temperature, solar radiation and precipitation during the millet growing season in the future (2021-2060) are higher than those in the baseline (1981-2020). The rainfed millet yield will decrease by 8.6 % (SSP245) and 16.5 % (SSP585) in the future without an adaptation strategy, compared to the baseline yield (2.43 t ha-1) in 1981-2020 under the conventional sowing date. The reduction in rainfed millet yield caused by climate change cannot be reversed by shifting sowing date, but can be slightly mitigated by a suitable advancement of the sowing date. Adopting supplemental irrigation in the future can achieve higher millet yield than the baseline yield, especially PSGI. Compared to PSI, PSGI consumes more irrigation water but has higher irrigation water use efficiency (IWUE). There is a synergy between shifting sowing date and supplemental irrigation in coping with climate change, and a later sowing date than the conventional one (30 April) is recommended under supplemental irrigation in the future. In 2021-2060, the best adaptation strategy to climate change for maximizing grain yield, IWUE and economic benefit in the millet production of the SXN is that supplementary irrigation is applied before sowing and on 20 July-30 July combined with the sowing dates of 10 May-20 May.