Biochar's role in improving cabbage quality and microbial community structure in rhizosphere soil

Abstract: Biochar amendments enhance crop productivity and improve agricultural quality. To date, studies on the correlation between different amounts of biochar in Chinese cabbage quality and rhizosphere soil microorganisms are limited, especially in weakly alkaline soils. The experiment was set up to explore the effect of different concentrations of biochar on vegetable quality and the correlation between the index of quality and soil bacterial community structure changes. The results revealed that adding 3% biochar significantly changed plants and increased the contents of plant physiology. Meanwhile, soil enzyme activities and available nutrient content in rhizosphere soil increased. This study demonstrated that the relative abundance of the bacterial community in cabbage rhizosphere soil was changed by applying more than 3% biochar. Adding 3% biochar reduced the relative abundance of Gemmatimonas and increased the relative abundances of Ilumatobacter, Luteolibacter, Lysobacter, Arthrobacter, and Mesorhizobium. The nitrate content was positively correlated with the abundance of Gemmatimonadetes, and the nitrate content was significantly negatively correlated with the relative abundance of Ilumatobacter. Carbohydrate transport and metabolism in the rhizosphere soil of Chinese cabbage decreased, and lipid transport and metabolism increased after biochar application. 3% biochar changed the relative abundance of dominant bacterial communities in the soil and improved the relative abundance of some functional bacterial communities, improved the soil nutrient environment, promoted Chinese cabbage growth, and reduced nitrate accumulation in leaves. This study provides a valuable reference for promoting biochar application in cabbage production.