Nitrated Hydrochar Reduce the Cd Accumulation In Rice and Shift the Microbial Community in Cd Contaminated Soil

Accumulation of cadmium in rice planted in Cd-contaminated soil could cause a severe toxicant impact on humans. A negative influence on Cd absorption of rice was found by hydrochar (HC) addition, which was reported more nutrient and lower phytotoxicity through nitric acid aging. However, there was little known about the effects and mechanisms of nitrated hydrochar (NHC) on Cd accumulation in rice. A rice-soil column experiment was carried out by applying HC and NHC to the soil at addition rates of 1% and 2% in present study. Results showed that NHC markedly promoted root biomass of rice by 58.70% - 72.78%, whereas these effects of HC were 35.86% - 47.57%. Notably, NHC at 1% application rate significantly inhibited the absorption of Cd in grain, root and straw by 28.04%, 15.08% and 11.07%, which attributed to the consistent reduction of ion-exchangeable Cd concentration by 36.30% in soil. Meanwhile, HC and NHC applications caused a great shift of soil microbial community. The relative abundance of Acidobacteria was decreased by 62.57% in NHC-2% compared to by 56.89% in HC-1%. Whereas, Protebacteria and Firmicutes were promoted by NHC addition compared to HC. Co-occurrence network of dominated bacterial families showed NHC generated a more complex and centralized network than HC. These observations provide an enrichment of paddy soil microbial responds to interaction of NHC with Cd and lay a foundation for the remediation of Cd-contaminated soil by NHC