Bangwei Zhang and colleagues, in their article published in Scientific Reports , investigate how biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More application rates and combinations with fertilizers influence nitrogen (N) dynamics in acidic soils of tea plantations. This study highlights effective strategies to improve N retention and optimize fertilization practices while minimizing losses.

The research used a 2-week aerobic incubation and ion-exchange membrane (IEM) techniques to assess soil N dynamics following early-summer top-dressing. The findings revealed that biochar does not directly increase N mineralization but significantly enhances the soil’s ability to retain mineral N. In acidic tea plantation soils, mineralized N levels were measured at 120–127 kg N/ha in the topsoil (0–20 cm) and 113–117 kg N/ha at a depth of 20–40 cm during summer.

A critical threshold was identified for biochar application: rates of 20–30 tonnes per hectare improved N retention and fertilizer effectiveness, while applications beyond 40 tonnes per hectare reduced the availability of inorganic N. This suggests that 20 tonnes per hectare is the optimal biochar application rate, balancing soil N supply and cost-effectiveness. Additionally, the study found that inorganic fertilizers applied in summer have a narrow window of maximum effectiveness—just 2–4 weeks. However, combining biochar with organic fertilizers extends this window, improving N availability and retention in the soil.

This research underscores the potential of biochar-based fertilizers to enhance nitrogen dynamics in tea plantations, offering sustainable solutions to reduce N losses and support soil health. By refining biochar application strategies, tea growers can improve nutrient management while reducing environmental impact.

Zhang, B., Liu, C., Li, Q., Ye, J., Lin, Y., Wang, Y., & Burton, D. L. (2025). Evaluating the effect of biochar rate and combination with fertilizer on the dynamics of soil nitrogen supply in tea plantation. Scientific Reports, 15(3135). https://doi.org/10.1038/s41598-025-87942-4