Fig. 1From: Biochar induced improvement in root system architecture enhances nutrient assimilation by cotton plant seedlingsActivities of the key enzymes involved in nitrogen metabolism in the fine and very fine roots of Gossypium hirsutum in the different treatments. GDH = Glutamic dehydrogenase, GPT = Glutamic-pyruvic transaminase, GOGAT = Glutamic synthase, and NR = Nitrate Reductase. Fine roots are those with diameter between 0.1 and 2 mm, while very fine roots are those with diameter less than 0.1 mm. The treatments include ck (control), sb (conventional 3.76 g urea kg−1 soil applied in the 0–10 cm soil layer), bb (conventional 3.76 g urea kg−1 soil applied in the 10–20 cm soil layer), soa (urea was reduced by 25% on the basis of sb plus 37.28 g biochar kg−1 soil), sob (urea was reduced by 50% on the basis of sb plus 37.28 g biochar kg−1 soil), boa (urea was reduced by 25% on the basis of bb plus 37.28 g biochar kg−1 soil), and bob (urea was reduced by 50% on the basis of bb plus 37.28 g biochar kg−1 soil). The last letters f and m of each treatment indicate very fine root and fine root, respectively. Results are presented as mean values for five plants with SE. Asterisk indicates significant difference with a confidence interval at *P < 0.05 or **P < 0.01Back to article page