Figure 3.

Boxplots for nitrogen (N): synthetic fertilizer (ton km^–2 year^–1), animal number in livestock unit (lu km^–2 year^–1, see Supporting Information for converting animal numbers in livestock unit), share of sown area of vegetable and fruit to the total sown area (%), N use efficiency (NUE) of food production, urban population (% of the total population), rural labor (capita km^–2 year^–1), total output value of agriculture and forestry (billion yuan km^–2 year^–1), and farmers’ incomes (1000 yuan capita^–1 year^–1) among the four groups of total N losses (see Figure 1) in 2012 (A), and the pairwise comparisons from Tukey’s Honest Significant Difference (Tukey’s HSD) among the four groups (B). In B panels any 95% confidence intervals that do not contain 0 provide evidence of a difference in the groups.