玉米秸秆还田配施腐熟剂对土壤微生物群落结构和功能的影响

Effects of maize straw returning combined with a decomposition agent on soil microbial community structure and function

摘要:

背景 山西省临汾市尧都区地处晋南旱作农业核心区，近年来秸秆还田比例持续提升，但受褐土黏化板结的特性制约，存在秸秆腐解速率慢问题，秸秆腐熟剂通过强化微生物代谢功能有效提升腐解效率，然而，目前秸秆还田配施腐熟剂对该区域土壤微生物的影响尚缺乏深入的认识。目的 阐明秸秆还田配施腐熟剂对褐土土壤微生物群落和功能的影响。方法 2021年秋季在国家农用微生物尧都观测实验点设置玉米秸秆还田配施腐熟剂试验，包括秸秆不还田、秸秆直接还田和秸秆还田配施腐熟剂3个处理。2024年小麦收获期采集各处理0-20 cm土壤，采用宏基因组测序技术分析土壤微生物群落结构和功能。结果 相较于秸秆直接还田，秸秆还田配施腐熟剂使小麦产量增加11.24%，土壤有机质、速效钾、有效磷及碱解氮的含量分别增加17.25%、36.39%、5.58%、9.87%，小麦茎基腐病的病情指数降低47.10%；显著增加了放线菌门(Actinomycetota)的相对丰度，属水平上显著提升了类诺卡氏菌属(Nocardioides)和金黄线菌属(Chryseolinea)的相对丰度。碳、氮代谢特征分析表明，在碳固定过程中，柠檬酸循环途径相关基因的丰度较高；在氮代谢过程中，同化硝酸还原途径相关基因的丰度较高；秸秆还田配施腐熟剂提升了参与碳固定和氮代谢相关功能基因的丰度，与假单胞菌门(Pseudomonadota)、放线菌门(Actinomycetota)、酸杆菌门(Acidobacteriota)、拟杆菌门(Bacteroidota)和亚硝化球形菌门(Nitrososphaerota)密切相关。结论 秸秆还田配施腐熟剂能提升土壤有机质和速效养分含量，提高土壤微生物群落和功能基因的丰度，为秸秆腐熟剂推广应用提供了一定的科学依据。

Abstract:

Background Yaodu district, Linfen city, Shanxi province, is located in the core area of dryland agriculture in southern Shanxi. In recent years, the proportion of straw returned to the field here has been increasing, while the straw decomposition is slow due to the characteristics of brown soil which is clayey and compacted. Straw decomposition agents can improve the decomposition efficiency by enhancing microbial metabolism, while the effects of straw returning combined with a decomposition agent on soil microorganisms in the region are not well understood at present.Objective To clarify the effects of maize straw returning combined with a straw decomposition agent on the microbial community structure and function in brown soil.Methods We designed three treatments at the national agricultural microbial observation experimental site in Yaodu in the autumn of 2021. The three treatments were no straw returning (UC), direct straw returning (SR), and straw returning combined with a decomposition agent (SD). We employed metagenomic sequencing to analyze the microbial community structure and function in the 0-20 cm soil layer during the harvesting stage of wheat in 2024.Results Compared with SR, SD increased the wheat yield by 11.24% and the soil organic matter, available potassium, available phosphorus, and alkali-hydrolyzable nitrogen by 17.25%, 36.39%, 5.58%, and 9.87%, respectively, while reducing the disease index of wheat crown rot by 47.10%. Additionally, SD increased the relative abundance of Actinomycetota. At the genus level, SD elevated the relative abundance of Nocardioides and Chryseolinea. Characterization of carbon and nitrogen metabolism showed that the abundance of genes related to the citrate cycle pathway was higher in carbon fixation and that of genes involved in the assimilatory nitrate reduction pathway was higher in nitrogen metabolism. SD increased the abundance of functional genes involved in carbon fixation and nitrogen metabolism, which were closely related to Pseudomonadota, Actinomycetota, Acidobacteriota, Bacteroidota, and Nitrososphaerota.Conclusion SD enhanced soil organic matter and available nutrients and increased the abundance of soil microbial communities and functional genes, which provides a scientific basis for the popularization and application of decomposition agents.