Constraints on maize yield and yield stability in the main cropping regions in China

Understanding the distributions of zones of high/low and stable/unstable recorded maize (Zea mays L.) yield, and identifying the constraints on yield and yield stability, is essential for optimized crop distribution and agricultural management to mitigate limitations and improve maize production under climate change. In this study, we collected recorded maize yields and simulated three levels of yield potentials (radiation-temperature yield potential Y-p climatic yield potential Y-pw and soil-climatic yield potential Y-pws) with the Agricultural Production Systems sIMulator (APSIM-Maize) from 1981 to 2010 in the three main cropping regions in China [the North China spring maize region (NCS), the Huanghuaihai summer maize region (HS), and the Southwest China mountain maize region (SCM)]. The distributions of four categories of maize yield and yield stability zones, and limitations by precipitation, soil and technology & management on average yield, yield stability and total production were analyzed. The county-level average recorded yields during the period under study were 4624.26 kg ha(-1), 4718.32 kg ha(-1) and 3880.44 kg ha(-1) in NCS, HS and SCM, respectively. Coefficients of variations (CV) for recorded yields were 0.40, 0.30 and 0.27 in NCS, HS and SCM, respectively. Based on comprehensive analysis of both average yields and CV values, we divided the main maize cropping areas into four zone categories: those with high and stable yields (high-stable zone), those with high and unstable yields (high-unstable zone), those with low and stable yields (low-stable zone), and those with low and unstable yields (low-unstable zone). Comparison of Y-p, Y-pw,Y-pws and Y-a at the county level, among the three regions, revealed that precipitation was the most important limiting factor on both averages (56%, 9436.97 kg ha(-1) and 53%, 8114.21 kg ha(-1)) and CVs (0.42 and 0.39) of yield in all four zone types in NCS and HS. On the other hand, technology & management was the most important limiting factor in SCM (39%, 3934.87 kg ha(-1)). Total maize productions were reduced by 47.6% and 52.7% by precipitation in NCS and HS, respectively. Nevertheless, the limiting effect of soil was lower than that of technology & management in NCS, while it was higher in HS. In SCM, technology & management was the most important limiting factor (1295.72 x 10(4) t and 39.3%), followed by precipitation (613.80 x 10(4) t and 18.6%) and soil (219.62 x 10(4) t and 6.7%). In the three main cropping regions, the limiting effect of each factor on total productions in high-stable zone was the highest among all four zone types. Our results could be used to provide a theoretical basis for targeted climate change adaptation policies to improve maize yield and yield stability in China. In addition, our results may serve as a reference for other maize cropping regions in the world.