The influence of biochar on soil urea hydrolysis process is associated with its potential ability on soil nitrogen amelioration. The objective of this study was to investigate the effect of biochar on urea hydrolysis and identify the main factors that drive their consequent behavior. The short-term incubation experiment was conducted to quantify the soil ureC gene copies and urea hydrolysis rate (UHR) as well as the gross N mineralization rate in response to biochar or its extracts pyrolyzed at 300 °C (BC300) and 600 °C (BC600). Biochar soil incorporation enhanced the ureC gene copies, and consequently increased the UHR by 39.49% (BC300) and 39.86% (BC600). Biochar addition also accelerated the gross organic N mineralization and NH₄⁺-N immobilization rates, which proved that biochar stimulated ureolytic microorganism abundance in response to urea hydrolysis. In comparison to control, BC300 extracts increased soil ureC gene copy number by 23.18%, while BC600 extracts showed an inhibition effect of 29.65%. Property analysis revealed that BC300 extracts contained lower concentrations of water-soluble phenols but higher concentrations of water-soluble carbon than BC600, which indicated that the stimulated soil ureolytic microorganism abundance was primarily attributed to an increase in biochar labile carbon. Meanwhile, the inhibition effect may be offset by biochar high pH thereby promoting the urea hydrolysis in BC600-amended soil. This study indicates that the considerable labile carbon in biochar stimulated the thriving of ureolytic microorganisms and, combined with liming effect, buffered the negative effect from phenols or other toxicities, and eventually increased the soil UHR.

生物炭对土壤尿素水解过程的影响与其对土壤氮素改善的潜在能力有关。本研究的目的是研究生物炭对尿素水解的影响，并确定驱动其后续行为的主要因素。进行短期孵育实验以量化土壤ureC基因拷贝和尿素水解率 (UHR) 以及响应于 300 °C (BC300) 和 600 °C 热解生物炭或其提取物的总氮矿化率（ BC600）。生物炭土壤掺入增强了ureC基因拷贝，从而使 UHR 增加了 39.49% (BC300) 和 39.86% (BC600)。添加生物炭也加速了总有机氮矿化和 NH ₄ ⁺-N 固定率，这证明 biochar 刺激尿素水解微生物的丰度以响应尿素水解。与对照相比，BC300 提取的土壤ureC增加基因拷贝数增加了 23.18%，而 BC600 提取物显示出 29.65% 的抑制作用。性质分析表明，与 BC600 相比，BC300 提取物含有较低浓度的水溶性酚类，但含有较高浓度的水溶性碳，这表明受刺激的土壤尿素分解微生物丰度主要归因于生物炭不稳定碳的增加。同时，生物炭的高pH可能会抵消抑制作用，从而促进BC600改性土壤中尿素的水解。这项研究表明，生物炭中相当多的不稳定碳刺激了尿素分解微生物的繁殖，并结合石灰效应，缓冲了酚类或其他毒性的负面影响，最终增加了土壤 UHR。