Urea hydrolysis in different farmland soils as affected by long-term biochar application

Urea is a commonly used nitrogen (N) fertilizer that contributes to world food production, and there have been increasing concerns about relatively low urea-N use efficiency. Biochar has shown the potential mitigate N loss, but how biochar influences urea hydrolysis underlying mechanisms are still unclear. In this study, long-term biochar-amended upland, paddy greenhouse soils were sampled at depths of 0–20 20–40 cm in Haicheng City, Northeast China. Soil contents, rates (UHRs), total, intracellular extracellular urease activities determined, as well total bacterial ureolytic microbial gene abundance quantified. The results showed increased activity by 32.64–66.39% upland soil 2.90–2.13-fold soil. Both ureases contributed increase activity. However, soil, (+35.07–74.22%) (−40.14–77.68%) responded inconsistently incorporation. Increases ureC copy numbers (2.15- 4.47-fold) (20.93%) implied stimulated microorganisms capable producing urease, liming effect pH (0.11–0.60 units), which optimized reaction, together explained increases We found decreased content was accompanied higher UHR soils, suggesting accelerated exerted negative on content, possibly caused excessive NH 3 volatilization. where not increased, an effective amendment for simultaneously improving content.