State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, P.O. Box 821, Nanjing 210008, PR China.
Nanjing Institute of Environmental Science, Ministry of Ecology and Environment, Nanjing 210042, PR China; Key Laboratory of Pesticide Environmental Assessment and Pollution Control, Ministry of Ecology and Environment, Nanjing 210042, PR China.
Sci Total Environ. 2020 Jun 1;719:137448. doi: 10.1016/j.scitotenv.2020.137448. Epub 2020 Feb 19.
Biochar can effectively alleviate the Al phytotoxicity in acidic soils due to its alkaline nature. However, the longevity of this alleviation effect of biochar under re-acidification conditions is still unclear. In the present study, the maize root growth responding to the simulated re-acidification of two acidic soils amended by peanut straw biochar or Ca(OH) was investigated to evaluate the long-term effect of biochar on alleviating Al toxicity in acidic soils. Compared with Ca(OH) amendment, the application of biochar significantly retarded Al toxicity to plant during soil re-acidification. When 4.0 mM HNO was added, the maize seedling root elongation in an Oxisol with biochar was 99% higher than that in the Oxisol with Ca(OH). Also, the Evans blue uptake and Al content in the root tip in the biochar treatment were 60% and 51% lower than those in the Ca(OH) treatment. The retarding effect was mainly attributed to the slow decrease in soil pH during acidification and the release of dissolved organic carbon (DOC) in the soils amended by biochar. The slower decrease in soil pH resulting from the increased pH buffering capacity after biochar application inhibited the increase of soluble and exchangeable Al during re-acidification. The increased DOC after biochar application decreased the toxic soluble Al speciation at the same pH value and total Al concentration in soil solution. Therefore, given the re-acidification of soils, biochar presented a longer-term effect on alleviating Al toxicity of acidic soil than liming.
生物炭由于其碱性性质，可以有效地缓解酸性土壤中的铝毒害。然而，在重新酸化条件下，生物炭这种缓解效果的持久性尚不清楚。本研究通过模拟两种酸性土壤的再酸化，研究了添加花生秸秆生物炭或 Ca(OH)对玉米根系生长的影响，以评估生物炭对缓解酸性土壤铝毒害的长期效果。与 Ca(OH) 相比，生物炭的应用显著延缓了土壤再酸化过程中铝对植物的毒害。当添加 4.0 mM HNO 时，添加生物炭的氧化土中玉米幼苗根伸长率比添加 Ca(OH)的氧化土高 99%。此外，生物炭处理的根尖 Evans 蓝摄取量和 Al 含量分别比 Ca(OH)处理低 60%和 51%。这种延缓作用主要归因于酸化过程中土壤 pH 缓慢下降和生物炭添加土壤中溶解有机碳（DOC）的释放。生物炭应用后 pH 缓冲能力的增加导致土壤 pH 缓慢下降，抑制了再酸化过程中可溶性和可交换性 Al 的增加。生物炭应用后 DOC 的增加降低了在相同 pH 值和土壤溶液中总 Al 浓度下的有毒可溶性 Al 形态。因此，考虑到土壤的再酸化，生物炭对缓解酸性土壤铝毒害的效果比石灰更为持久。
