堆肥添加剂降低碳氮损失的微生物学机制研究

为了探明添加剂如何影响堆肥微生物优势群落的演替进而影响碳氮损失，以玉米秸秆和鸡粪为原料，添加不同量的生物质炭和凹凸棒作为添加剂，设置5个处理（CK （鸡粪+玉米秸秆）、BC1（鸡粪+玉米秸秆+5%（干重）生物质炭）、BC2（鸡粪+玉米秸秆+10%（干重）生物质炭）、PG1（鸡粪+玉米秸秆+5%（干重）凹凸棒）和PG2（鸡粪+玉米秸秆+10%（干重）凹凸棒））进行堆肥.结果表明，相较于CK，BC1、BC2、PG1、PG2处理的碳和氮损失分别减少了8.60%、12.05%、2.03%、6.14%和14.54%、20.14%、8.40%、11.23%.优势微生物菌群与碳氮损失的冗余分析表明，添加10%生物质炭和添加10%凹凸棒都显著促进了堆肥过程中固氮类细菌相对丰度，而抑制反硝化细菌的相对丰度，且添加10%生物质炭效果更佳；KEGG分析表明，添加10%生物质炭显著影响氨基酸代谢和碳水化合物代谢功能基因，而添加10%凹凸棒显著影响氨基酸代谢功能基因.由此可见，10%添加剂的碳氮损失都低于5%添加剂的处理，添加生物质炭的碳氮损失都低于凹凸棒处理，添加剂通过影响优势微生物群落及其氨基酸代谢和碳水化合物代谢功能基因抑制堆肥过程中的碳氮代谢，从而减少碳氮损失.

Microbiological mechanism of reducing carbon and nitrogen loss by composting additives

The primary objective of the study was to analyze how compost additives influenced the succession of predominant microbiota during composting process to affect the losses of C and N. Co-compost of chicken manure (CM) and corn stover (CS) with additives of biochar (5% and 10%, dry weight basis) and attapulgite (5% and 10%, dry weight basis) was conducted and the samples were marked as CK, BC1, BC2, PG1 and PG2, respectively. Results indicated that the losses of C (8.60%, 12.05%, 2.03% and 6.14% in BC1, BC2, PG1 and PG2 groups) and N (14.54%, 20.14%, 8.40%, and 11.23% in BC1, BC2, PG1 and PG2 groups) were all significantly lower than those in the CK group. Redundancy analysis (RDA) between predominant microbial species and the losses of C and N indicated that 10% addition of BC and PG both promoted the growth and relative abundance of nitrogen fixing microorganisms, and inhibited the growth and abundance of denitrifying microorganisms. Analysis based on Kyoto Encyclopedia of Genes and Genomes (KEGG) showed that 10% BC significantly affected genes associated with amino acid and carbohydrate metabolism, while PG2 significantly affected genes associated with amino acid metabolism. Overall, the losses of carbon and nitrogen in the compost went down as the dosage of the additives went up from 5% to 10%, and BC showed better performance on improving the quality of the compost than PG. Both additives reduced the loss of carbon and nitrogen during composting by altering the microbial community through regulating genes associated with amino acid metabolism and carbohydrate metabolism, which could be utilized to improve compost quality for co-composting manure and agricultural waste.