Evaluation of agricultural potential of chicken manure biochar: growth and nitrogen use efficiency of kimchi cabbage and N2O emissions of upland soil

This study investigated the effects of chicken manure biochar (CMBC), produced via co-pyrolysis of chicken manure and woody biomass (80:20 w/w) at 400℃, on the growth, nitrogen use efficiency, and nitrous oxide (N 2 O) emissions of kimchi cabbage ( Brassica rapa ssp. pekinensis ) in upland soil. The experiment compared a control group, inorganic fertilizer (IF), and three CMBC application rates (3, 5, and 7 t ha⁻¹, referred to as CMBC3, CMBC5, and CMBC7, respectively). Post-harvest soil analysis revealed that CMBC application increased soil pH, organic matter, available phosphate, and cation exchange capacity (CEC) compared with the control and IF treatments, with these effects showing a dose-dependent pattern. While the IF treatment yielded the highest fresh weight (1,453 g plant − 1 ), CMBC7 showed significant growth improvement (1,244 g plant − 1 ) and achieved the highest head height (23.2 cm plant − 1 ). Notably, CMBC7 demonstrated superior nitrogen dynamics, reaching the highest agronomic efficiency (AE_N: 8.88 kg N ha − 1 ) and apparent recovery fraction (ARF_N: 26.0%), both of which surpassed the IF treatment. Furthermore, CMBC application significantly mitigated N 2 O emissions by 59.2% to 72.1% compared to the IF treatment. These results suggest that applying CMBC at 7 t ha − 1 is an effective strategy for enhancing soil fertility and nitrogen use efficiency while simultaneously reducing greenhouse gas emissions in intensive vegetable production systems.