| In order to study the effects of humic acid in overcoming cropping obstacles of flue-cured tobacco, three trials in the field were set including control (B1), local conventional fertilization (B2), and humic acid fertilizer (B3), to investigate the changes of nitrogen accumulation and quality in flue-cured tobacco. The results showed that root nitrogen accumulation tended to be increased during reproduction, reaching the highest level with B3 treatment, 32.62% higher than that by B2 during harvest. Stem nitrogen accumulation with B3 treatment was 41.62% higher than that with B2, exhibiting significant differences. Nitrogen accumulation in lower leaves with B3 treatment was 35.37% higher than that with B2 treatment. Middle leaves with B3 were 14.61% higher than those with B2 treatment, displaying significant differences. Upper leaves with B3 were 32.64% higher than those with B2 treatment, showing significant differences. B3 treatment promoted distribution of nitrogen into stem, 5.27% and 1.84% higher than B1 and B2 treatments, respectively. Yield with B3 was 6.94% and 7.94% higher than B1 and B2, respectively. Leaf qualities of lower, middle, and upper leaves scored 1.50, 2.00, and 2.00 lower than those with B2 treatment. Comprehensive analysis indicated that humic acid played important roles in improving nitrogen accumulation, resulting in best yield of flue-cured tobacco. |