Miscanthus-Derived Biochar Enhanced Soil Fertility and Soybean Growth in Upland Soil

As biochar improves soil fertility and crop productivity, there is a growing interest in it as a resource for sustainable agriculture. Miscanthus sacchariflorus has promising applications in various industries because it has a large amount of biomass. However, research on the agricultural utilization of Miscanthus-derived biochar is insufficient. The aim of this study was to demonstrate the effects of Miscanthus biochar on the soil environment and soybean growth. First, Miscanthus biochar was amended at different levels (3 or 10 tons/ha) in upland soil, after which the soil properties, root development, and yield of soybeans were compared with the control (without biochar). In the soil amended with 10 tons/ha of biochar (BC10), organic matter (OM) and available phosphate increased 1.6 and 2.0 times, respectively, compared with that in the control soil (CON). In addition, the soil dehydrogenase activity increased by 70% in BC10, and 16S rRNA gene sequence analysis revealed that the structure of the microbial community changed after amendment with biochar. The bacterial phyla that differed between CON and BC10 were Acidobacteria and Chloroflexi, which are known to be involved in carbon cycling. Owing to these changes in soil properties, the root dry weight and number of nodules in soybeans increased by 23% and 27%, respectively, and the seed yield increased 1.5-fold in BC10. In conclusion, Miscanthus biochar increased the fertility of soybean-growing soil and consequently increased seed yield. This study is valuable for the practical application of biochar for sustainable agriculture.