Soil bacterial community response to biochar and P-solubilizing bacterial inoculum in a maize field

This field experiment on maize under reduced irrigation tested three soil conditioners: precision application of engineered coconut hull biochar (600ºC, 0.8Mg ha-1), soil P-solubilizing bacterial inoculum, and a co-application of inoculated biochar treatment. At the early maize growth phase (V4) and reproductive phase (R1), we measured soil nutrient supply with ion strips, maize leaf/ grain nutrient content, and bacterial community structure by sequencing amplicon sequence variants of 16S rRNA genes. The biochar treatment increased maize yield by 20% over the control, increasing early season supply of K and later season supply of S, which correlated to crop nutrient uptake. The biochar also changed the microbial community composition early in the season. Indicator taxa analyses revealed bacteria in the following phyla closely associated with the biochar treatment: Bacteroidetes, Chloroflexi, Proteobacteria, and Planctomycetes, as found in previous biochar studies. The inoculum treatment and combined treatment shifted bacterial community structure later in the season, but had no measurable impact on soil nutrients, uptake, or yield.