Modified biochar-immobilized Bacillus spp. for the release of nutrients and its response to soil microbial community activity and structure
Jie Cheng, Qiwu Sun, Lei Liu
Abstract
In response to the growing fertilizer demand due to population expansion and the environmental challenges arising from inefficient fertilizer use, this study presented an innovative biochar-based microbial fertilizer (BMF) by integrating biochar, pyroligneous acid, and Bacillus spp., focusing mainly on its nutrient slow-release characteristics and the underlying mechanisms driving its potential effects on soil microbial community structure. The abundance of -OH groups provided by BMF with a significant advantage in the adsorption of nitrogen, phosphorus, and potassium nutrients. When pyroligneous acid and Bacillus spp. were added to biochar in a 1:1 ratio, the mixture exhibited excellent slow-release properties. By constructing a multitrophic ecological network, soil microorganisms were categorized into several modules. In the treatments with biochar, pyroligneous acid, and Bacillus spp., the top three modules, ranked by node count, were Modules 1, 2, and 3. These modules represented 19.57 %, 9.78 %, and 7.61 % of the total nodes, respectively. This study would contribute to understanding how to scientifically and strategically apply biochar, pyroligneous acid, and Bacillus spp. to optimize the efficient utilization of nitrogen, phosphorus, and potassium in soil. • Integrating biochar, pyroligneous acid, and Bacillus exhibited well release properties. • Pyroligneous acid might facilitated acylation reactions with nitrogen-containing compounds. • Biochar-based microbial fertilizers enhanced the ecological function of the bacterial community. • Surface-modified biochar demonstrated positive association with the plant characteristics. • N-N or N-O bonds formed on the biochar surface could preventing nutrients loss.