Abstract:

Soil acidification in tea gardens has become an important factor restricting the development of tea industry. Biochar has shown superior performance for short-term amelioration of acid soil in tea gardens, yet the temporal effectiveness and long-term environmental effects of biochar on acid soil improvement remain unclear. In this study, two different amounts (20 and 40 t∙hm^-2) of biochar were applied to study its performance in ameliorating acidified tea garden soil, and the changes of physicochemical properties and the microstructure of biochar were evaluated after 5 years of application. Results showed that the pH of tea garden soil increased by 0.77 and 1.11 units after 5 years, when biochar application rate was 20 and 40 t∙hm^-2. The surface morphology of biochar after aged for 5 years was physically broken and exfoliated, resulting in the decrease of specific surface area and increase of average pore size. However, the overall pore structure remained relatively unchanged. Surface Na, S and Cl disappeared in aged biochar, whereas the contents of Si, Fe, Al, H and N increased, suggesting that biochar can improve soil acidity by reducing exchangeable Al and soil exchangeable H⁺. Furthermore, the characteristic absorption peaks of lignin and cellulose in biochar disappeared, indicating that the number of oxygen-containing functional groups decreased and the content of aromatic ether C-O bond increased during the aging process of biochar. No significant differences in the changes of physicochemical properties and microstructure of aged biochar were observed between the two application rates. This study manifests that biochar is stable and has long-term effects on the amelioration of acidified tea garden soil.

Key words: biochar, stability, tea garden, soil acidification, physicochemical properties, microstructure

摘要：

茶园土壤酸化已成为制约茶产业发展的一个重要因素,生物炭对土壤酸度改良显著,在茶园试验短期效果良好,但生物炭对酸性土壤改良的时效性及长期环境效应尚不清楚。该研究设置生物炭田间施入量分别为20、40 t∙hm^-2,探讨生物炭酸性茶园土壤改良效应,并对施入茶园土壤5 a后生物炭理化性质及微观结构进行表征。结果表明,生物炭施入量为20、40 t∙hm^-2的茶园土壤在5 a后pH分别提高了0.77和1.11个单位;施入茶园土壤5 a的生物炭,表面形貌发生了物理破碎和剥离现象,但整体孔道结构完整,比表面积减小,平均孔径增大;生物炭表面Na、S、Cl元素消失,Si元素含量增多,新增了Fe、Al元素,生物炭中H含量和N含量升高,因此生物炭可以通过降低土壤交换性铝和土壤交换性酸而改良土壤酸化;生物炭中木质素和纤维素的特征吸收峰消失,说明生物炭在老化过程中含氧官能团数量减少,芳香醚C-O键含量增多。茶园施入量分别为20、40 t∙hm^-2的生物炭5 a后理化性质及微观结构无显著差异。施入茶园5 a的生物炭结构稳定,具有持续改良酸性土壤的潜能。

关键词: 生物炭, 稳定性, 茶园, 土壤酸化, 理化性质, 微观结构