Arsenic Immobilization for Paddy Field and Improvement of Rice (Oryza sativa L.) Growth through Cerium–Manganese Modified Wheat Straw Biochar Application

Abstract

Arsenic (As) frequently emerges in paddy soils, necessitating measures to combat soil pollution and protect rice crops from As contamination. In this study, a novel functional biochar (MBC) by loading cerium manganese oxide was prepared, and its effects on soil As immobilization and As uptake by rice in two different As-contaminated paddy soils of 68.99 and 158.52 mgAs·kg−1 (marked as soil-L and soil-H, respectively) were detected. The pot experiment manifested that MBC performed better in stabilizing soil As than original biochar. The incorporation of MBC facilitated the conversion of soil active As to the stable state, promoted the growth of rice plants, and reduced As uptake by rice. Specifically, the total plant biomasses for MBC treatment were increased by 16.13–70.07% and 12.36–92.58% in soil-L and soil-H compared with CK (without material input), respectively. MBC treatments resulted in a reduction of As contents by 34.67–60.13% in roots, 43.68–66.90% in stems, and 54.72–64.65% in leaves for soil-L. Furthermore, in soil-H, the As content in rice roots, stems, and leaves showed a decrease by 49.26–79.03%, 87.10–94.63%, and 75.79–85.71% respectively. This study provides important insights for the remediation of As-contaminated paddy soil using MBC.