Objective The improvement effects of biochar types made from different raw materials and carbonization temperature on acidified brown earth were investigated, and the effects of biochar on rape growth and soil organic carbon (SOC) mineralization were clarified. Efficient materials for improving acidified brown earth were obtained.
Method Three kinds of raw materials (tree branch, peanut shell and cow dung) were used to prepare biochar at different carbonization temperatures (300 ℃, 450 ℃ and 600 ℃). We investigated the effects of the application with three kinds of biochar on the improvement of acidified brown earth, rape growth and SOC mineralization.
Results The results showed that biochar application significantly increased the soil pH by 8.10%-40.99%, and clearly decreased the exchangeable acidity, exchangeable aluminum and exchangeable hydrogen by 61.57%-88.43%, 42.71%-85.83% and 78.03%-94.02%, respectively. The contents of malondialdehyde (MDA) and glutathione (GSH), the activities of superoxide dismutase (SOD) and glutathione reductase (GR) in rapes were significantly decreased by biochar additions. The plant height, leaf and yield were increased by 18.09%-44.61%, 17.87%-77.13% and 37.50%-159.68%, respectively. The applications of biochar decreased the SOC cumulative mineralization rates, and increased the proportion of mineral bound organic carbon. Biochar paralyzed at 450 ℃ and 600 ℃ could reduce the cumulative mineralization rates compared with 300 ℃.
Conclusion Biochar from fruit tree branches and cow dung had stronger mitigation effect on soil acidity and SOC mineralization. And biochar types paralyzed at 450 ℃ and 600 ℃ were stronger than that at 300 ℃. Overall, biochar from cow dung at 450 ℃ had the best improvement effect on acidified brown earth, but it also promoted SOC mineralization.
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