Effect of combined biochar (B) and nitrogen fertilizer (N) rates on GWP (A) and GHGI (B). CN (sole N; average, 195 kg N/ha), LBLN (B ≤ 9 t/ha + N ≤ 140 kg N/ha), LBMN (B ≤ 9 t/ha+140 < N ≤ 240 kg N/ha), LBHN (B ≤ 9 t/ha + N > 240 kg N/ha), MBLN (9 < B ≤ 20 t/ha + N ≤ 140 kg N/ha), MBMN (9 < B ≤ 20 t/ha+140 < N ≤ 240 kg N/ha), MBHN (9 < B ≤ 20 t/ha + N > 240 kg N/ha), HBLN (B > 20 t/ha + N > 240 kg N/ha). Bars with different letters are statistically different from each other (p < 0.05). The error bars represent the standard deviation of the mean.