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Chemical characterization of rice straw-derived biochar for soil amendment
- Wu, Weixiang, Yang, Min, Feng, Qibo, McGrouther, Kim, Wang, Hailong, Lu, Haohao, Chen, Yingxu
- Biomass and bioenergy 2012 v.47 pp. 268-276
- chemical composition, crystallites, rice, cation exchange capacity, greenhouse gas emissions, fertilizers, bioenergy, cations, heat, soil amendments, biochar, carbon sequestration, rice straw, soil fertility, alkalinity, analytical methods, temperature, biomass, pyrolysis, phosphorus
- Pyrolysis of rice straw to create biochar for soil amendment appears to be a promising method to address concerns with regard to improving soil fertility, increasing Carbon storage and decreasing Green House Gas emissions. However, the ability of rice straw-derived biochar to affect these factors might vary depending on its characteristics. It is therefore essential to investigate the properties before large-scale application of rice straw-derived biochar. In this study, rice straw-derived biochars produced at different temperatures (300, 400, 500, 600 & 700 °C) and residence time (1, 2, 3 & 5 h) were characterized using a suite of analytical techniques. Results showed that pyrolysis temperature had a greater influence than residence time on the chemical composition and structure of rice straw-derived biochar produced at low heating rate. The rice straw-derived biochars especially produced at 400 °C had high alkalinity and cation exchange capacity, and high levels of available phosphorus and extractable cations. These properties indicate potential application of rice straw-derived biochar as a fertilizer and soil amendment. Fourier transform infrared spectra showed that higher pyrolysis temperatures promote condensation reactions. Rice straw-derived biochars contained turbostratic crystallites at 400 °C, and displayed a high level of aromatization at 500 °C. Increasing charring temperature will increase the aromaticity of biochar, and might include its recalcitrance.