Difference of the ratio of maize stovers to grain and spatiotemporal variation characteristics of maize stovers in China

Since maize stovers resources are abundant in China, the ratio of stovers to grain is mostly used to estimate the stovers resources in the statistical methods. However, the recommended value for the ratio of stovers to grain deviates greatly from the actual one. This study aims to analyze the differences in the ratio of stovers to grain from the maize stovers in 9 provinces in China, thereby to explore the amount and distribution of maize stovers resources. According to the measured value for the ratio of stovers to grain, the spatial and spatiotemporal changes were evaluated on maize stovers resources in the past 10 years, and consequently predicted the potential of maize stovers resources. The results showed that the measured value was (0.84±0.23)for the ratio of stovers to grain in the maize stovers. The ratio of stovers to grain varied significantly in different regions and species. The improvement of corn species and changes in planting patterns resulted in the decrease in the ratio of stovers to grain year by year. From 2009 to 2018, the ratio of stovers to grain decreased from 1.2 to 0.8.The collection coefficient of maize stovers was becoming lower, as the mechanized harvest rate of corn increased, indicating a decrease from 0.93 in 2009 to 0.88 in 2018. In 2018, while, the theoretical output of maize stovers in China was 2.16×108t, only 3.9% increased from 2009. The corn stalk resources were highest in the Northeast and North China, accounting for more than 50% of the total. Compared with the output of 2009, the theoretical output of stovers in the Northeast, North China and Northwest increased by 1 142.8×104, 224.4×104 and 109.6×104 t in 2018. The theoretical output in the East, Central, Southwest, and South China declined slightly, indicating that reduced by 110×104-220×104 t. The ratio of stovers to grain of maize stovers decreased gradually, and the collection output of maize stovers per unit area decreased, as the region from north to south, and from west to east. Collection output of maize stovers per unit area was 4.51 t/hm2, showing an increase of 23% over 2009’s.The sort of collection output of maize stovers can be the Northeast, North China, East, Northwest, then Central, Southwest, and then South China. The theoretical output of maize stovers and the collection output were predicted to be (2.53±0.58)×108 t, and (1.86±0.51)×108 t in 2025. It was recommended to revise the existing statistical data of stovers resources, according to the measured value of ratio of stovers to grain. The finding can provide a basic reference data for rational planning and utilization of maize stovers.