鸡粪好氧堆肥过程氨气与温室气体排放特征及协同减排机制

为研究畜禽粪便好氧堆肥过程氨气(NH₃)与温室气体的排放特征及协同减排机制,以鸡粪与蘑菇渣为原料,设置9组不同条件的好氧堆肥正交实验,并进行为期45 d的跟踪监测,了解好氧堆肥过程基本理化参数变化,分析NH₃和温室气体的排放规律及最佳减排条件,探究微生物群落与环境因子、气体排放通量之间的相关性。结果表明:含水率与碳氮比(C/N)变化影响整个堆肥进程,经45 d堆肥后,大多数处理组的堆肥均已经完全腐熟,且添加一定比例的椰壳生物炭与钙镁磷肥可以提高堆肥腐熟度。NH₃和4种温室气体(CH₄、N₂O、CO、CO₂)在堆肥前期(1~22 d)排放通量较高,人工翻堆会增加气体排放通量。NH₃和温室气体排放的影响因子和最佳减排条件各不相同,存在"此消彼长"的关系。对NH₃、CH₄、N₂O排放影响较大的因子是椰壳生物炭占比、钙镁磷肥占比和通风速率,有利于这3种气体协同减排的条件为含水率60%、椰壳生物炭0或5%、钙镁磷肥0或5%或10%、通风速率0.12 L·min^-1·kg^-1,其中含水率60%、椰壳生物炭占比5%、通风速率0.12 L·min^-1·kg^-1是NH₃和CH₄协同减排的最佳条件。整个堆肥过程中,门水平与属水平的微生物群落相对丰度均发生明显变化,C/N和温度是微生物群落变化的主要驱动因素;堆肥前期(22 d前),门水平的优势菌为Firmicutes、Actinobacteria、Bacteroidetes和Proteobacteria,其中Firmicutes对NH₃与温室气体的排放具有显著影响。研究表明,鸡粪好氧堆肥过程中影响NH₃和温室气体排放的因子很多,通风条件下进行调理剂种类及配比优选有望实现NH₃、CH₄和N₂O的协同排放。

Emission characteristics and the mechanism of synergistic emission reduction for NH3 and greenhouse gases during the aerobic composting of chicken manure

To study the emission characteristics of NH₃ and greenhouse gases and the mechanism of synergistic emission reduction during the aerobic composting of livestock and poultry manure, nine groups of orthogonal experiments for aerobic composting were performed with a mixed feedstock of chicken manure and mushroom residue under different conditions, and 45 d of tracking and monitoring were performed to understand the changes in the basic physicochemical parameters, analyze the emission rules and optimal emission reduction conditions of NH₃ and greenhouse gases during the process of composting, and explore the correlation between the microbial community and environmental factors, the gas emission flux. The results showed that the changes in the moisture content and C/N affected the whole composting process. The composts of most treatment groups were completely decomposed after 45 d, and the addition of coconut shell biochar and calcium magnesium phosphate fertilizer (suitable proportion) improved the maturity of the composts. NH₃ and four greenhouse gases (CH₄, N₂O, CO, and CO₂) both had high emission fluxes during the early stage of composting(1-22 d), and manual heap turning increased their emission fluxes. NH₃ and greenhouse gas emissions had different impact factors and optimal emission reduction conditions, and different gases showed no evident consistency with one another. The major factors affecting the NH₃, CH₄, and N₂O emissions were the proportions of coconut shell biochar and calcium magnesium phosphate fertilizer, and the aeration rate. The synergistic conditions that were beneficial for reducing the emissions of three gases were a water content of 60%, coconut shell biochar addition at 0 or 5%, calcium magnesium phosphate fertilizer addition at 0, 5%, or 10%, and an aeration rate of 0.12 L·min^-1·kg^-1; among them, a water content of 60%, coconut shell biochar addition of 5%, and aeration rate of 0.12 L·min^-1·kg^-1 were the best conditions for the synergistic reduction in the NH₃ and CH₄ emissions. Throughout the composting process, the relative abundance of the microbial community at the phylum and genus levels changed obviously, and the C/N and temperature were the main driving factors of the changes in the microbial community. During the early stage of composting (22 d before), the dominant bacteria at the phylum level were Firmicutes, Actinobacteria, Bacteroidetes, and Proteobacteria, among which Firmicutes had a significant effect on the emissions of NH₃ and greenhouse gases. Many factors could affect NH₃ and greenhouse gas emissions during the aerobic composting of chicken manure, and the optimal selection of conditioner types and ratios under aeration conditions is expected to achieve synergistic emissions reduction of NH₃, CH₄, and N₂O.