Extended Data Fig. 1: Flowchart for determining wheat production zone based on N management benchmarks at national and regional scales.

The boundaries for determining crop N output is 150 kg N ha⁻¹ season⁻¹, and N surplus is between 5.96e^{0.0061×N input} and 80 kg N ha⁻¹ season⁻¹ in China. In the spring wheat area of North China, the winter wheat area of North China, the winter wheat area of North China Plain, the winter wheat area of South China, the boundaries for determining crop N output is 115, 115, 175, and 130 kg N ha⁻¹ season⁻¹, and N surplus is between 6.39e^{0.0059×N input} and 85 kg N ha⁻¹ season⁻¹, 6.39e^{0.0059×N input} and 80 kg N ha⁻¹ season⁻¹, 8.60e^{0.0049×N input} and 80 kg N ha⁻¹ season⁻¹, and 4.66e^{0.0065×N input} and 85 kg N ha⁻¹ season⁻¹, respectively.