Biochar stimulates tea growth by improving nutrients in acidic soil

The benefits of biochar application for enhancing plant growth by improving soil fertility have been widely documented. However, there is little information on the effects of biochar on the growth of tea [Camellia sinensis (L.) Kuntze]. We conducted a pot experiment to investigate the effects of biochar type (bamboo and rice) and application rate (2.5 % and 5.0 % w/w) on the growth and nutrient uptake of tea and the effects of biochar application on soil pH and nutrient availability. Both bamboo biochar and rice biochar applied at rates of 2.5 % and 5.0 % significantly improved tea growth compared with the control, while no significant differences were observed among the biochar treatments. The biochar treatments increased the plant P, K, and Mg concentrations, which all showed significant positive relationships with the aboveground biomass, leaf area, and rate of photosynthesis. The soil pH and available P, K, and Mg concentrations were increased by biochar application, which contributed to improved tea nutrients. Moreover, significant decreases in the plant Mn and Cu concentrations were observed with the biochar treatments, which were related to the increased soil pH and reduced soil-available Mn and Cu concentrations. This study showed that biochar could be used as a soil amendment to improve soil quality and promote tea growth by supplying P, K, and Mg and reducing the heavy metals Mn and Cu.