Azotobacter Raw sequence reads

Soil amendments have been widely used to remediate heavy metal contaminated soils. However, the potential impacts of soil amendments on soil properties, Cd bioavailability, and bacterial community in Cd-contaminated paddy soils are not clear. In this study, MgO-Cao-SiO2 conditioner (A), Fe-modified biochar (B), and MgO-Cao-SiO2 + organic matter (C) with two different application rates (2250 kg ha-1 (A150, B150, C150), 4500 kg ha-1 (A300, B300, C300)) were applied to investigate their impacts on soil properties, soil Cd bioavailability, stem and rice Cd uptake in a field experiment. Bacterial community composition was also assessed using high-throughput sequencing based on 16S rRNA gene. Compared with CK, soil pH and cation exchange capacity (CEC) were significantly elevated whereas soil Cd bioavailability was lower in soil amendments treated treatments, and soil pH and CEC were significantly and positively correlated with soil available Cd. Soil amendments applications significantly decreased Cd concentration in rice straw and grain, with lowest Cd concentration in the C300 treatment. Soil amendments significantly increased bacterial Chao and Shannon indexes and altered its community composition, with shifts in community structure mostly driven by soil pH, soil Cd and nutrients availability. Structural equation model showed that soil amendments could improve bacterial shannon index and changed soil pH and CEC, which were conducive to inhibit the migration and transformation of Cd. These results show that soil amendments induced the interactions among soil chemical properties, soil available Cd, and bacterial community assembly are key in remediating heavy contaminated paddy soils.