生物炭对铝富集酸性土壤的毒性缓解效应及潜在机制

Mitigative Effect of Biochar on Aluminum Toxicity of Acid Soil and the Potential Mechanism

【目的】红壤铝毒是土壤改良持续关注的问题之一。生物炭因其自身的理化和生物学特性,为探索解决该难题提供了新的思路和途径。论文通过在红壤中添加外源铝并种植作物,研究生物炭对铝富集土壤铝毒的缓解效应及潜在机制。【方法】选用酸性红壤做盆栽试验,种植小白菜,添加花生壳生物炭和外源铝,设置CK(0C+0Al)、C(2%C)、Al(1 mmol·L^(^(-1))Al)、C+Al(2%C+1 mmol·L^(^(-1))Al)4个处理,分析生物炭对铝富集红壤不同活性铝及作物生长的影响。【结果】铝毒会显著抑制小白菜的出苗,且加重红壤小白菜生长受抑制的情况,降低小白菜的生物量,同时,铝毒会显著提高小白菜铝含量。而施用生物炭能缓解铝毒对小白菜的抑制影响,显著改善小白菜的生长状况,降低小白菜铝含量,C+Al处理小白菜铝含量较Al处理降低89.4%。铝毒会显著降低红壤的pH,Al处理红壤pH较CK处理降低了0.36个单位,而施用生物炭能显著提高土壤pH,C+Al处理土壤pH较Al处理上升0.62个单位。Al处理较CK处理土壤活性铝含量上升276.4μg·g^(-1),远大于添加量(27μg·g^(-1)),而施用生物炭能显著降低土壤活性铝含量,C+Al处理较Al处理下降14.9%。此外,Al处理交换性Al^(3+)含量较CK处理上升23.1%,施用生物炭后,C+Al处理交换性Al^(3+)含量较Al处理下降46.5%。CK与Al处理土壤活性铝形态主要以具有生物毒害性的交换性Al^(3+)为主,C与C+Al处理土壤活性铝形态主要以单聚体羟基铝离子、胶体Al(OH)30为主。【结论】添加外源铝降低了土壤pH,加重铝的毒害,抑制作物的生长发育。此外,外源铝的添加对红壤中活性铝有较强的激发效应,使得交换性Al^(3+)含量显著升高。然而,生物炭能显著提高酸性土壤pH,且改变不同活性铝的含量,但其对4种不同形态活性铝的效应有较大差异,其主要通过降低具有生物毒性的Al^(3+)含量来缓解铝毒,从而改善作物生长状况。

【Objective】Aluminum toxicity of acid soil is one of the hot topics in soil science research, and biochar with some bio-characters give a new method to solve this problem. The objective of this experiment is mainly to clarify the mitigative effect of biochar on aluminum toxicity of acid soil and the potential mechanism. 【Method】 An experiment including CK（0C＋0Al）, C（2%C）, Al（1 mmol·L（-1）Al）, and C＋Al（2%C＋1 mmol·L（-1）Al） treatments indoor planting pakchoi in pots added with biochar and exogenous aluminum was conducted. The effects of biochar on different active aluminum and the growth of crop of aluminum enrichment red soil were analyzed. 【Result】 The results showed that aluminum toxicity significantly decreased the emergence rate of pakchoi. The growth of pakchoi restrained significantly and the biomass of pakchoi decreased under aluminum toxicity, meanwhile, the Al content of the pakchoi increased significantly under aluminum toxicity. However, the growth of pakchoi improved significantly and the Al content reduced under biochar addition, and the aluminum content of C＋Al treatment pakchoi reduced by 89.4% compared with Al treatment. Aluminum toxicity decreased the pH of the red soil, the pH of Al treatment decreased by 0.36 compared with CK treatment, but the pH of the red soil increased significantly under biochar addition, the pH of C＋Al treatment increased by 0.62 compared with Al treatment. The active aluminum of Al treatment was 276.4 mg·kg（-1） more than CK treatment. Application of biochar decreased the active aluminum of red soil, and the active aluminum in C＋Al treatment decreased by 14.9% compared with Al treatment. Besides, the exchangeable Al（3＋） of Al treatment increased by 23.1% compared with CK treatment, but the exchangeable Al（3＋） of C＋Al treatment decreased by 46.5% compared with Al treatment. The main active aluminum form of CK and Al treatment soil was the exchangeable Al（3＋） that had biological toxicity, the main active aluminum form of C and C＋Al treatment soil was dimer hydroxy aluminum ion and colloid Al（OH）30. 【Conclusion】 Exogenous aluminum had a strong stimulating effect on the addition of active aluminum of red soil. Exchangeable Al（3＋） which has biological toxicity increased significantly under aluminum toxicity. Besides, adding exogenous aluminum can decrease the p H and stimulate the poison, restrain the growth of the crops. Although application of biochar can increase the p H and ease the aluminum toxicity of red soil, its effect on different 4 forms of active aluminum has a quite large difference. Application of biochar can reduce the poison by decreasing the exchangeable Al（3＋） which has biological toxicity, and thus improve the growth of crop.