Effects of biochar and biochar-based fertilizer on forest growth and soil fertility

Objective In order to study the impacts of biochar and biochar-based fertilizer application on the growth, nutrient uptake, and soil fertility of Michelia macclure, and provide a scientific foundation for encouraging the use of biochar in nutrient management on forest land

Method Taking the young forest of M. macclure as the research object, six treatments were set up, including no fertilization (CK) and application of compound fertilizer (CF), rice husk biochar (RB), wood chip biochar (WB), rice husk biochar based fertilizer (RBF), and wood biochar based fertilizer (WBF). After one year, the growth indices, quality indices, nutrient contents, and soil physicochemical properties of M. macclurei were measured.

Result Compared with CK, the biomass, leaf area, leaf N content, and root N accumulation of M. macclure treated with biochar significantly increased, with the increases of 59.1%−62.2%, 44.7%−66.0%, 29.5%−45.4%, and 68.6%−92.3%, respectively. The Dickson quality index and whole-plant N, P, and K accumulations increased significantly when compound and biochar-based fertilizers were applied, with the increases of 136.8%−192.2%, 167.7%−267.4%, 124.4%−224.5%, and 191.5%−265.5%, respectively. Moreover, the application of compound fertilizer and biochar-based fertilizers had a greater impact on the growth of M. macclurei than the application of biochar alone. The application of biochar-based fertilizer was found to promote both plant growth and soil improvement when compared to application of compound fertilizer alone. The RBF treatment significantly increased the soil pH, soil quick-acting K content, and SPAD value by 13.4%, 6.2%, and 99.7% respectively, while the WBF treatment significantly increased the whole-plant P and K accumulations and total biomass by 31.5%, 44.6%, and 22.1% respectively, and the soil bulk density significantly decreased by 17.3%. The fuzzy affiliation function revealed that the overall impact of treatments on M. macclurei growth and enhancement of soil physicochemical qualities was evaluated in the following order: WBF > RBF > CF > WB > RB > CK.

Conclusion While both biochar and biochar-based fertilizer can enhance the physical and chemical characteristics of soil and successfully encourage the growth and uptake of nutrients by M. macclurei, wood chip biochar-based fertilizer yields the greatest overall results and offers a novel approach to managing nutrients in forest areas.