有机-无机肥变更对水稻土微生物群落结构的影响

Effects of organic-inorganic fertilization regime alterations on microbial community structures in paddy soils

摘要:

目的 探究变更施肥对水稻土微生物群落的影响。方法 在长期定位试验田中设置3组变更施肥模式处理：化肥与化肥改常量有机肥；常量有机肥与常量有机肥改化肥；高量有机肥与高量有机肥改化肥。通过宏基因组测序结合生物信息学分析研究施肥模式变更对土壤微生物群落结构、多样性及互作网络的影响。结果 与化肥处理相比，化肥改常量有机肥处理显著提高了土壤有机碳、溶解性有机碳、全氮和碱解氮的含量(P<0.05)。常量有机肥改化肥处理和高量有机肥改化肥处理的土壤碳、氮水平分别低于常量有机肥处理和高量有机肥处理。化肥改常量有机肥处理显著改变了酸杆菌、硝化螺菌、Candidatus Rokubacteria、毛霉菌和奇古菌的丰度；常量有机肥改化肥处理未显著改变水稻土微生物群落的相对丰度(门水平)；高量有机肥改化肥处理显著改变了硝化螺菌的相对丰度和古菌群落的组成。改变施肥模式对土壤微生物α多样性无显著影响(P>0.05)，但不同施肥处理之间微生物群落的β多样性存在显著差异(P<0.05)。网络分析显示，与化肥处理相比，化肥改常量有机肥处理的节点数(181)、边数(2 935)、平均度(16.215)、模块化(0.757)及平均聚类系数(0.495)均更高；常量有机肥改化肥处理的边数(3 894)和平均度(21.514)高于常量有机肥处理，而模块化(0.599)低于常量有机肥处理(0.751)；高量有机肥改化肥处理的网络拓扑参数均低于高量有机肥处理。冗余分析表明，溶解性有机碳(22.1%)、土壤pH (16.8%)、全氮(15.6%)、铵态氮(14.6%)、速效钾(11.8%)和有效磷(10.6%)是驱动微生物群落变化的主要因子。结论 变更施肥模式通过改变土壤理化因子影响了水稻土微生物群落结构和网络特征。无机肥变更为有机肥可优化微生物群落结构，增强土壤生态功能；而有机肥变更为无机肥施入可能降低土壤碳、氮供应水平，对土壤微生物群落的稳定性和复杂性产生负面影响。

Abstract:

Objective To investigate the effects of fertilization regime alterations on microbial communities in paddy soils.Methods We conducted a long-term field experiment with three treatments: chemical fertilizer (H) and H converted to a conventional amount of organic fertilizer (HC), a conventional amount of organic fertilizer (C) and C converted to chemical fertilizer (CH), and a high amount of organic fertilizer (G) and G converted to chemical fertilizer (GH). Metagenomic sequencing was combined with bioinformatics analysis to assess the structures, diversity, and co-occurrence networks of microbial communities in paddy soils.Results Compared with the H treatment, the HC treatment increased the soil organic carbon, dissolved organic carbon, total nitrogen, and alkali-hydrolyzable nitrogen (P<0.05). The CH and GH treatments exhibited lower soil carbon and nitrogen levels than C and G treatments, respectively. The HC treatment markedly altered the relative abundance of Acidobacteriota, Nitrospirota, Candidatus Rokubacteria, Mucoromycota, and Thaumarchaeota. The CH treatment showed no significant changes in microbial composition at the phylum level, whereas the GH treatment significantly modified the relative abundance of Nitrospirota and the archaeal community structure. Although fertilization regime alterations showed no significant effect on microbial alpha diversity (P>0.05), the beta diversity differed across treatments (P<0.05). Co-occurrence network analysis demonstrated that the HC treatment enhanced the network complexity relative to the H treatment, with increased nodes (181), edges (2 935), average degree (16.215), modularity (0.757), and clustering coefficient (0.495). The CH treatment showed more edges (3 894) and higher average degree (21.514) but lower modularity (0.599) than the C treatment (0.751). Conversely, the GH treatment diminished all network topology parameters relative to G. Redundancy analysis identified dissolved organic carbon (22.1%), soil pH (16.8%), total nitrogen (15.6%), ammonium nitrogen (14.6%), available potassium (11.8%), and available phosphorus (10.6%) as the primary drivers of microbial community variations.Conclusion The findings indicate that fertilization regime alterations influence the microbial community structure and network characteristics in paddy soils by modifying soil physicochemical properties. Transitioning from chemical to organic fertilization enhances microbial community stability and soil ecological functions, while replacing organic with chemical fertilization reduces soil carbon and nitrogen availability, potentially compromising microbial network complexity and resilience.