LAUSR

China is entering an impressive era of grain production since its reform and opening up in 1978. At present, China feeds 22% of the world population with only 9% of the world’s arable land [1]. Thus, China has become a leader in the global fight against hunger [2]. Grain production has increased dramatically, from about 3 10 t in 1978 to 6.21 10 t in 2016, which is an annual increase rate of 9% [3]. The increase rate of grain production has surpassed the growth rate of the population, resulting in an evident decrease in the proportion of malnourished people in China. However, the doubling of agricultural food production since 1978 in China is partly attributed to a three-fold increase in nitrogen (N) fertilization, an 11-fold increase in phosphorus (P) fertilization, and a 1.5-fold increase in the amount of irrigated cropland [3,4]. Huge inputs of various agricultural resources (fertilizers, water, insecticides, etc.) for grain production have caused an enormous waste of resources [4], which is a great challenge for realizing the goal of green development in agriculture and sustainable grain production in the future.