Zhang Li, Li Ru-Xia, He Yu-Lei, Yao Yan-Po, Lin Da-Song
Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China.
Shilin Yi Autonomous County Agricultural Technology Extension Station, Kunming 652200, China.
Huan Jing Ke Xue. 2023 Aug 8;44(8):4479-4488. doi: 10.13227/j.hjkx.202208274.
Cadmium (Cd) heavy metal pollution has posed serious threats to soil health and the safe production utilization of agricultural products. A pot experiment was conducted to study the effects of biochar (BC) and nitrogen fertilizer with three levels, namely 2.6 g·pot (N1), 3.5 g·pot (N2), 4.4 g·pot (N3) biochar combined with nitrogen fertilizer (BCN1, BCN2, and BCN3), on soil Cd fractions, Cd enrichment, the transport of rice, and soil enzyme activity, as well as the changes in microbial community composition and complex interactions between microorganisms through high-throughput sequencing. The results showed that biochar combined with nitrogen fertilizer led to the transformation of Cd from the exchangeable state to the residue state, and the proportion of the exchangeable state was significantly reduced by 6.2%-14.7%; by contrast, the proportion of the residue state increased by 18.6%-26.4% relative to that in CK. In addition, singular treatments of nitrogen fertilizer enhanced the accumulation capacities of Cd in roots, which increased by 22%-33.5% compared with that in CK. By contrast, the BC and BCN treatments reduced Cd accumulation in roots and the transfer capacity from stems to rice husks and husk to rice. Furthermore, the BCN treatments promoted soil enzyme activities (urease, acid phosphatase, invertase, and catalase). MiSeq sequencing showed that BCN treatments increased the abundance of the main species of soil bacterial microbes (such as Acidobacteriales, Solibacterales, Pedosphaerales, and Nitrospirales). Moreover, co-occurrence network analysis showed that the complexity of the soil bacterial network was enhanced under the N, BC, and BCN treatments. Overall, biochar combined with nitrogen fertilizer reduced soil Cd availability, inhibited the capacity of Cd accumulation and the transport of rice, and improved the soil eco-environmental quality. Thus, using BCN could be a feasible practice for the remediation of Cd-polluted agricultural soil.
镉（Cd）重金属污染对土壤健康和农产品安全生产利用构成了严重威胁。进行了一项盆栽试验，研究生物炭（BC）与三种水平氮肥（即2.6 g·盆（N1）、3.5 g·盆（N2）、4.4 g·盆（N3））生物炭与氮肥组合（BCN1、BCN2和BCN3）对土壤镉形态、镉富集、水稻转运以及土壤酶活性的影响，以及通过高通量测序分析微生物群落组成变化和微生物之间复杂的相互作用。结果表明，生物炭与氮肥组合导致镉从交换态向残渣态转化，交换态比例显著降低6.2%-14.7%；相比之下，残渣态比例相对于对照增加了18.6%-26.4%。此外，单施氮肥处理增强了镉在根部的积累能力，与对照相比增加了22%-33.5%。相比之下，BC和BCN处理降低了镉在根部的积累以及从茎到稻壳和从稻壳到糙米的转运能力。此外，BCN处理促进了土壤酶活性（脲酶、酸性磷酸酶、转化酶和过氧化氢酶）。MiSeq测序表明，BCN处理增加了土壤细菌微生物主要种类（如酸杆菌目、芽孢杆菌目、球形杆菌目和硝化螺旋菌目）的丰度。此外，共现网络分析表明，在N、BC和BCN处理下土壤细菌网络的复杂性增强。总体而言，生物炭与氮肥组合降低了土壤镉的有效性，抑制了镉的积累和水稻的转运能力，改善了土壤生态环境质量。因此，使用BCN可能是修复镉污染农田土壤的一种可行做法。
