The impacts of a biochar application on selected soil properties and bacterial communities in an Albic Clayic Luvisol

In this four-year study, we focused on the impacts of a biochar application on physicochemical soil properties (soil total carbon, total nitrogen, total potassium, total phosphorus, available nitrogen, available potassium, available phosphorus, pH, bulk density and moisture) and bacterial communities in an Albic Clayic Luvisol. The biochar was applied to plots only once with rates of 0, 10, 20 and 30 t/ha at the beginning of the experiment. The soil samples were collected from the surface (0-10 cm) and second depth (10-20 cm) soil layers after four years. The results showed that that the soil total carbon (TC) and pH increased, but the soil bulk density (BD) decreased with the biochar application. The soil bacterial sequences determined by the Illumina MiSeq method resulted in a decrease in the relative abundance of Acidobacteria, but an increase in the Actinobacteria with the biochar application. The bacterial diversity was significantly influenced by the biochar application. The nonmetric multidimensional scaling (NMDS) and canonical correspondence analysis (CCA) indicated that the soil bacterial community structure was affected by both the biochar addition and the soil depth. The Mantel test analysis indicated that the bacterial community structure significantly correlated to a soil with a pH (r = 0.525, P = 0.001), bulk density (r = 0.539, P = 0.001) and TC (r = 0.519, P = 0.002) only. In addition, most of the differences in the soil properties, bacterial relative abundance and community composition in the second depth soil layer were greater than those in the surface soil layer.