Biochar as a novel carrier affects Brassica napus L. growth, soil phosphorus fractions, and its uptake

Biochar increases soil fertility by enhancing nutrients retention in amended soil. In addition, biochar increases phosphorus availability in soil by reducing leaching process. The performance of biochar serving as an inoculum carrier depends on physicochemical properties (pH, porosity and, surface area) that impact the establishment of plant growth-promoting bacteria in amended soil. Biochar is largely used as a soil amendment for soil remediation and plants growth. However, little work has been conducted considering biochar suitability when applied as a carrier, which has resulted in inconsistent outcomes. In the present study, six biochar carriers including rice straw biochar (RSB), rice husk biochar (RHB), soybean straw biochar (SSB), peanut shells biochar (PNB), corn cobs biochar (CCB), and wood biochar (WB) were prepared and inoculated with liquid suspension of a phosphate solubilizing bacteria (PSB) identified as Bacillus megaterium KU647234 in a pot experiment. The data revealed that rape (Brassica napus L.) growth and biomass were significantly (P≤ 0.05) improved by up to 304% with amendments of carriers, particularly soybean straw (SSB). P bioaccumulation in roots, stems, and leaves increased significantly (P≤ 0.05) by up to 74%, 111%, and 75% respectively. In addition, RSB, SSB, RHB, PNB, WB, and CCB amendments Plate count assay data revealed that six carriers sustained the Bacillus megateriumabundance to varying degrees. The SSB carrier was identified as the best carrier that sustained higher rape biomass, and P bioaccumulation compared with other carriers