Effect of biochar and its combined fertilizers on the dynamics of soil nitrogen supply in tea plantation

Background and Aims: Tea plantations are frequently given substantial quantities of nitrogen fertilizers. However, there is the potential for considerable nitrogen loss to occur. This study assesses the nitrogen retention of acidic tea plantation’s soil and the role of biochar in improving nitrogen dynamics, highlighting the need for innovative technologies to streamline and enhance nitrogen supply management. Methods: Adopting a modified two-week aerobic incubation and ion-exchange membrane technology, this research offers a novel approach to evaluate soil nitrogen supply and to monitor the nitrogen dynamics of tea plantation soil following early-summer supplementary fertilization. Results: The study revealed that the surface soil of tea plantation had the ability to provide 48 mg N·kg ^-1 soil as inorganic nitrogen for 130 days. The utilization of a small amount of biochar (10 t·ha ^-1 ) had no impact on the soil's effective nitrogen availability. Nonetheless, the application of biochar at rates of 20 and 30 t·ha ^-1 resulted in a significant enhancement in soil effective nitrogen availability as measured using ion exchange membranes, with an increase of 65%–81%. Furthermore, the utilization of biochar-based organic fertilizers, when used at appropriate rates, has the potential to enhance the availability of nitrogen in the soil, thereby increasing its effectiveness. Conclusion: The study's findings underscore the efficacy of the employed methodologies in capturing the nuanced impact of biochar on nitrogen retention and availability in tea plantation soils. The use of aerobic incubation and ion-exchange membrane technology has proven effective in elucidating the potential of biochar to significantly improve nitrogen dynamics.