Ceramic Pellet-Based Microbial Formulations Reduce Soil Cadmium Levels and Improve Soil Microbial Community Structure

In order to remove the available cadmium (Cd) content in farmland soil, cadmium-tolerant strains were screened and combined with ceramic pellets as bio-modified ceramic pellets, and the effect of bio-modified ceramic pellets on soil and plant Cd content and soil microbial community structure was conducted through pot incubation. The results showed that Cd-tolerent bacteria were successfully isolated. Bacillus sp. h10 decreased Cd2+ content by 9.14% in solution. The bio-modified ceramic pellets (Ce-B1) showed a better adsorption rate of 88%, a more stable solution adsorption process, and a high removal rate (reached 66.26%) of soil available Cd. The removal rate of soil available Cd was Ce-B1>Ce-3>Ce-2>Ce-1>H, which was proportional to the applied amount and soil pH, and new functional groups on surface of the ceramic were involved for Cd adsorption in soil. At the same time, Ce-B1 increased Pak choi yield, reached at 113.64 g per pot, and reduced 58.86% Cd uptake by plants. The results of soil bacterial community structure analysis showed Ce-B1 generally promoted the diversity of soil microbial community structure and enriched dominant groups such as Firmicutes and Bacillus genus. Thus, the use of bio-modified ceramic pellets provides new ideas for soil heavy metal remediation