不同堆肥工艺处理的城市污水污泥对滨海湿地土壤中养分释放特征和潜力的影响

通过土壤培养实验研究了4种不同堆肥［纯城市污水污泥堆肥、玉米秸秆生物炭（CSB）改良堆肥、益生菌菌剂（EM）改良堆肥和CSB+EM改良堆肥］在土壤中的碳、氮、磷和钾等养分释放特性及其对土壤溶解有机质（DOM）光谱特征、微生物群落的影响.结果表明，堆肥添加可显著降低土壤的pH，提高土壤的电导率，同时提高土壤中植物可利用养分［如可溶性有机碳（DOC）、NH₄⁺-N、NO₃^--N、速效磷（AP）和速效钾（AK）］含量；比较不同堆肥发现CSB+EM改良堆肥（CSB+EM-C）具备更高的养分释放潜力，且同时显著提高土壤DOM的腐殖化程度；高通量测序结果发现堆肥添加可以增加优势菌门水平上的相对丰度（如变形菌门、厚壁菌门、拟杆菌门和放线菌门），但不同堆肥之间有所差异，其中CSB+EM-C的提高潜力最大.综合上述结果证实CSB+EM的堆肥工艺具有最佳的堆肥养分供应和改善土壤质量的潜力.该研究能够为建立有效的城市污水污泥资源化利用和滨海湿地退化土壤改良综合技术策略提供科学的理论依据.

Effects of Different Biochar and Effective Microorganism Agent Improvement Approaches on the Nutrient Release Characteristics and Potential of Compost

The nutrient release characteristics of four types of composts, pure municipal sewage sludge compost, corn straw biochar (CSB) improved compost, effective microorganism agent (EM) improved compost, and CSB+EM improved compost, in coastal wetland soil were examined through a soil incubation experiment. The effects of different composts on the spectral characteristics of soil dissolved organic matter (DOM) and microbial community were also investigated. The results demonstrated that the compost additions could significantly reduce soil pH, while increasing soil electrical conductivity and contents of plant available nutrients (e.g., dissolved organic carbon, NH₄⁺-N, NO₃^--N, available phosphorus, and available potassium). By comparing the nutrient release potential among the improved composts, the CSB+EM-improved compost (CSB+EM-C) evidently had the highest nutrient release potential. Furthermore, the DOM in CSB+EM-C amended soil exhibited a higher humification degree than that of the other composts. The high-throughput sequencing results indicated that the compost additions increased the relative abundances of dominant bacteria at the phylum level, such as the Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria. CSB+EM-C exhibited a greater potential to improve the relative abundance of these dominant bacteria phyla than other improved composts. Overall, among all the improvement approaches, the combined use of CSB and EM agent was the optimal composting strategy owing to its highest potentials of nutrient supply and soil quality improvement. The present findings can provide a solid scientific theoretical basis for establishing an effective technology strategy involving the combination of municipal sewage sludge utilization and degraded coastal wetland soil remediation.