Pedosphere 34(5): 929--940, 2024
ISSN 1002-0160/CN 32-1315/P
©2024 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Biochar regulates biogeochemical cycling of iron and chromium in a soil-rice system by stimulating Geobacter and Clostridium |
Min XU1,2, Yang LIN2, Jing MA3, Lulu LONG1, Chao CHEN1, Gang YANG1, Chun SONG1, Jun WU1 , Xiaohong ZHANG1, Peng GAO4 |
1 College of Environmental Science, Sichuan Agricultural University, Chengdu 611130 (China);
2 Soil, Water, and Ecosystem Sciences Department, University of Florida, Gainesville FL 32611 (USA);
3 College of Water Conservancy and Hydropower Engineering, Sichuan Agricultural University, Yaan 625014 (China);
4 Department of Environmental and Occupational Health, University of Pittsburgh School of Public Health, Pittsburgh PA 15261 (USA) |
| ABSTRACT |
| In soil-rice systems, microbial reduction of iron (Fe) has been recognized as a crucial biogeochemical process that regulates Fe and chromium (Cr) translocation; however, the underlying processes are unknown. To investigate the impacts of biochar on the biochemical cycling of Fe and Cr and their toxicity to rice, maize straw biochar was applied at 1% (weight/weight) to a paddy soil spiked with 300 mg kg-1 Cr under two phosphorus (P) levels (0 or 90 mg kg-1) in a pot experiment. The key microbial groups affecting Fe dissimilatory reduction and their environmental drivers were explored. Biochar inhibited root Cr uptake by 36%, owing to the promoted iron plaque (IP) formation on the rice root surface. Correlation analysis showed that Fe concentration in pore water was strongly linked to the abundances of Geobacter (r = 0.81-0.94, P < 0.05) and Clostridium (r = 0.83-0.95, P < 0.05), indicating that Geobacter and Clostridium played essential roles in Fe reduction. Redundancy analysis showed that labile carbon and pore water P concentrations were the key determinants influencing Fe-reducing bacterial abundances, accounting for 42% and 32% of the variation in community composition, respectively. Besides, biochar increased Fe and P concentrations in root cell walls, which retained more Cr. Overall, Cr stress in rice under biochar treatment was relieved through increasing IP formation and altering subcellular distribution. These mechanistic insights had important implications for reducing Cr uptake by rice. |
| Key Words: chromium translocation,iron plaque,iron reduction,maize straw biochar,microbial reduction,paddy soil,phosphorus fertilization,subcellular distribution |
| Citation: Xu M, Lin Y, Ma J, Long L L, Chen C, Yang G, Song C, Wu J, Zhang X H, Gao P. 2024. Biochar regulates biogeochemical cycling of iron and chromium in a soil-rice system by stimulating Geobacter and Clostridium. Pedosphere. 34(5): 929-940. |
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