Abstract
Replacing biosilicon and biocarbon in soil via biochar amendment is a novel approach for soil amelioration and pollution remediation. The unique roles of silicon (Si)-rich biochar in aluminum (Al) phytotoxicity alleviation have not been discovered. In this study, the alleviation of Al phytotoxicity to wheat plants (root tips cell death) by biochars fabricated from rice straw pyrolyzed at 400 and 700 °C (RS400 and RS700) and the feedstock (RS100) were studied using a slurry system containing typical acidic soils for a 15-day exposure experiment. The distributions of Al and Si in the slurry solution, soil and plant root tissue were monitored by staining methods, chemical extractions and SEM-EDS observations. We found that the biological sourced silicon in biochars served dual roles in Al phytotoxicity alleviation in acidic soil slurry. On one hand, the Si particles reduced the amount of soil exchangeable Al and prevented the migration of Al to the plant. More importantly, the Si released from biochars synchronously absorbed by the plants and coordinated with Al to form Al-Si compounds in the epidermis of wheat roots, which is a new mechanism for Al phytotoxicity alleviation in acidic soil slurry by biochar amendment. In addition, the steady release of Si from the rice straw-derived biochars was a sustainable Si source for aluminosilicate reconstruction in acidic soil.
Highlights
Soil amendment by adding biochar is a novel and practical approach which may replace biosilicon and biocarbon for soil amelioration and pollution remediation[1,2,3,4,5,6,7,8]
After adding 1% rice straw (RS1001), the weight of the wheat roots increased to 127 mg/10 plants, and the weight of the shoot increased from 326 mg/10 plants to 400 mg/10 plants (RS1001)
When the amount of rice straw was increased to 5%, the root and shoot length were not further increased as compared with RS1001
Summary
Soil amendment by adding biochar is a novel and practical approach which may replace biosilicon and biocarbon for soil amelioration and pollution remediation[1,2,3,4,5,6,7,8]. The alleviation of Al phytotoxicity to wheat plants (root tips cell death and root elongation) by rice straw-derived biochars pyrolyzed at 400 and 700 °C (RS400 and RS700) was investigated using a slurry system containing typical acidic soils (oxisol) in a 15-day exposure experiment. The amendment of RS700 at 1% and 5% showed a similar trend to that of RS400, which confirmed that biochars can be used as effective materials to ameliorate the plant root growth inhibition in acidic soil, such as oxisol.
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