施用生物炭对重金属污染农田土壤改良及玉米生长的影响

为了解生物炭的农业环境效应,采用大田试验,研究了不同生物炭施用量(0、5、10、20、30 t·hm-2)对韶关仁化县矿区周边重金属污染农田土壤理化性质、玉米(粤甜9号)生长状况、产量及重金属累积等的影响。结果表明:与对照(CK)相比,生物炭显著提高土壤pH值和有机质质量分数,其提升幅度随施用量的增加而升高,而土壤阳离子交换量随施用量的增加先升高后降低;生物炭施加量达到30 t·hm-2时,土壤速效钾含量是CK处理的3.1倍,但不同生物炭施用量对土壤碱解氮含量的影响没有显著性差异;不同用量生物炭均能降低土壤Pb和Cd的含量,降低幅度分别为11.3%和23.9%。各处理均能有效降低Pb、Cd在玉米粒、玉米芯、玉米叶和玉米秆中的累积。当施用量为20 t·hm-2时,玉米粒中Pb的含量降低幅度达49.4%,Cd的降低幅度达45.4%;生物炭对玉米的增产效果随施用量的增加而增加,分别为CK的1.75、6.16、8.84倍和8.90倍。综上所述,生物炭通过提高土壤pH值和有机质含量,实现了对南方酸性土壤的改良,对玉米产量具有促进作用,可降低污染土壤重金属的生物有效性。

Impacts of biochar application on amelioration of heavy metal-polluted soil and maize growth

In the present study, a field trial was adopted to study the effect of biochar application at different concentrations(0, 5, 10, 20 t·hm^-2 and 30 t·hm^-2) on the physicochemical properties of the heavy metal-polluted farmland soil near mining areas in Renhua, Shaoguan, China. In addition, we investigated the impacts of biochar on the growth and yield of maize(Yuetian 9) as well as on the accumulation of heavy metals in the crops. The results indicated that the addition of biochar significantly elevated the soil pH and organic matter fractions compared with the CK treatments, and the rate of increase was positively related to the amount of biochar applied. Conversely, the cation exchange capacity of soil first increased and then decreased with an increase in the amount of biochar applied. When the biochar application amount was 30 t·hm^-2, the content of available potassium in soil was approximately 3.1 times of that in the CK treatments; however, the addition of different amounts of biochar showed no significant impact on the content of hydrolysable nitrogen in soil. The soil contents of Pb and Cd reduced by 11.3% and 23.9%, respectively, regardless of the application amount of biochar. A significant reduction was observed in the accumulation of Pb and Cd in the grain, cob, leaf, and stalk of maize in all biochar treatments. When the biochar application amount was 30 t·hm^-2, the contents of Pb and Cd in maize grain decreased by 49.4% and 45.4%, respectively. With the application of 5, 10, 20 t·hm^-2 and 30 t·hm^-2 biochar, the maize yields were 1.75, 6.16, 8.84 times and 8.90 times higher than that in CK treatment, respectively, indicating that the maize yields increased with an increase in the amount of biochar applied. Overall, the application of biochar ameliorated the acidified soil in Southern China by increasing its pH and organic matter content, subsequently promoting the yield of maize and reducing the bioavailability of heavy metals in contaminated soils.