Assessment of the direct radiation effect of atmospheric aerosol on maize yield in China by using APSIM model

Owing to the increasingly serious atmospheric aerosol pollution, the impact of aerosols on the growth and development of crops can no longer be ignored. In this paper, the Beijing, Xianghe, and Taihu stations in China with perennial observation data in global aerosol monitoring network (AErosol RObotic NETwork, AERONET) were used as the research stations. Based on the AERONET data, MODIS surface albedo data and the 6S (Second Simulation of a Satellite Signal in the Solar Spectrum) radiation transfer model, the effects of aerosol direct radiation at three research stations from 2001 to 2014 were calculated. Then, the applicability of the APSIM (Agricultural Production Systems Simulator) model was evaluated, and the impacts of direct aerosol radiation on maize yield in China were analyzed by using the APSIM model. The results showed that:1) the verified APSIM maize model had good applicability in the maize producing areas of Beijing, Xianghe, and Taihu in China. The results of APSIM model were a better simulation of the developmental stages and the yield of maize, in which normalized root mean square error (NRMSE), coincidence indicator (D), and determinate coefficient (R²) were 1.55%-6.24%, 0.80-0.99, and 0.75-1.00, respectively. 2) Aerosols reduced direct solar radiation, and the decreasing trend was mainly affected by the net radiation flux of aerosols. The total solar radiation of Beijing, Xianghe, and Taihu stations reduced by 31.95%, 14.74% and 28.30%, respectively, from 2001 to 2014. 3) The direct radiation effect of aerosols caused a reduction in maize yield. The maize yields of the Beijing, Xianghe, and Taihu stations, caused by the direct radiation effect of aerosols, were reduced by 28.44%, 14.89%, and 13.43%, respectively, from 2001 to 2014. In general, because of the direct radiation effects of atmospheric aerosols, the maize yields from 2001 to 2014 were reduced by 13.43%-28.44% in three highly polluted areas (Beijing, Xianghe, and Taihu) in China.