Objectives Combustible gases and biochar were prepared by the pyrolysis of brewing solid waste. An investigation on the influence of the biochar on soil and crop yield was then carried out to provide a theoretical basis for the judicious use of biochar in crop cultivation as a strategy for waste-to-wealth.
Methods The surface structure of biochar produced by pyrolysis at different temperatures (400°C, 480°C, and 600°C, respectively) was examined by an electron microscope. Selected physical and chemical properties of biochar produced at 480°C (BC) were analyzed. Thereafter, the influence of BC on crop yield and selected soil properties was studied in a sorghum-canola rotation field in Luzhou, Sichuan. The field treatments included no fertilization (CK), chemical fertilization (CF), and chemical fertilizers plus BC (CF+BC).
Results BC had a better surface pore structure and larger cation exchange capacity (33.41 cmol/kg) with a pH of 10.1, and contained higher C, N, P, and K. Compared with CF, CF+BC treatment significantly increased soil organic carbon, microbial biomass carbon and nitrogen, sucrase and phosphatase activities, and available nutrients including available N, P, and K. These results suggested the utilization of some BC by microbes, promotion of microbial growth, and increment of enzymes and nutrient biological availabilities in the soil. The application of chemical fertilizers in combination with BC increased canola yield by 9.3%, sorghum yield by 9.5%; phosphorus and potassium economic efficiencies by 15.1% and 30.7%, respectively.
Conclusions The biochar prepared by pyrolysis temperature at 480℃ has excellent physical and chemical properties. The application of biochar with chemical fertilziers is beneficial to enhance canola and sorghum yields, improve soil physical, chemical, and biological properties, with promising potentials for sustainable crop production.
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