烟秆炭修复重金属污染土壤的效应及对烟草生长的影响

为了评估烟秆炭修复重金属污染土壤上种植烟草Nicotiana tabacum的可行性，以烟秆炭作为土壤修复剂，以重金属污染土壤为研究对象，利用盆栽实验研究了不同烟秆炭施加量（0，20，40，80 g·kg-1）对重金属污染土壤肥力、重金属生物有效性、土壤酶活性指数及烟草产量、烟叶重金属质量分数的影响。结果表明:施用烟秆炭可以显著提高重金属污染土壤pH值、土壤肥力和土壤酶综合活性指数，显著降低污染土壤重金属生物有效性。与对照相比，添加80 g·kg-1的烟秆炭对土壤肥力的改善、酶活性指数的提升和对土壤中镉的钝化效果最好，土壤有机质和有效磷质量分数分别显著（P < 0.05）提高了2.0倍和3.4倍，土壤酶指数显著提升了24.8%；但施用施加40 g·kg-1的烟秆炭已能使铜、铅的钝化效果达到最佳，与对照相比分别显著（P < 0.05）下降了33.7%和29.5%。另一方面，施用烟秆炭能显著（P < 0.05）增加烟草有效叶数和叶片的宽度，烟叶鲜质量在炭施加量为40 g·kg-1时达到最高，比对照显著（P < 0.05）提高了近50.0%，同时烟叶中铜、镉质量分数降至最低。综合分析当烟秆炭施加量为土壤总质量的4%时，其对重金属污染土壤的修复效果最好。因此，利用烟秆制成的生物质炭修复重金属污染土壤种植烟草是可行的。

Tobacco stalk biochar in heavy metal contaminated soil amendments with tobacco production

To assess the impacts of tobacco stalk biochar on tobacco (Nicotiana tabacum) growth and leaf yield, soil properties and metal immobilization in soil, and non-bioavailability to plants in a soil contaminated with Cu, Pb, and Cd, a pot experiment with biochar application rates of 0, 20, 40, and 80 g·kg-1 was conducted in Pingshan Experimental Ground in Zhejiang A&F University in 2016. And the biochar was mixed with 4 kg soil filled into plastic pots in a randomized design with 4 replications per treatment. Results compared to the control with no biochar additions, showed increases in soil pH, soil fertility, and soil enzyme activity indices as well as a decrease in soil heavy metal bioavailability with increasing application of biochar from 20 g·kg-1 to 80 g·kg-1. With a biochar application rate to the soil of 80 g·kg-1, content of soil organic matter and soil available P increased significantly (P < 0.05) (2.0 and 3.4 times, respectively), and the geometric mean of enzyme activities (GMea) also significantly increased (P < 0.05) (24.8%). Additionally, 40 g·kg-1 of biochar added to the soil led to the highest immobilization effect with decreases on Cu (33.7%) and Pb (29.5%) in the soil. Furthermore, with addition of biochar to the soil both number of tobacco leaves and foliar biomass increased significantly (P < 0.05). With a biochar application rate of 40 g·kg-1 to the soil, foliar fresh biomass was highest at nearly 50% higher than the control. At the same application rate of biochar to soil (40 g·kg-1), Cu and Cd concentrations in tobacco leaves significantly decreased (P < 0.05) to the lowest level. Thus, it may be feasible to use biochar derived from tobacco stalk waste to remediate metal-contaminated soils which can then be re-used for tobacco cultivation, and based on this study, 4% would be a suitable application rate for the biochar.