基于宏基因组学方法分析化肥减施对热带地区菜地土壤微生物群落的影响

为了探究化肥减量配施有机肥对热带地区蔬菜轮作土壤细菌、真菌和古菌群落组成和结构的影响,在海南省文昌市开展田间定位试验,采用宏基因组测序技术分析不同施肥方式下土壤细菌、真菌和古菌群落结构和组成的变化特征,并结合土壤理化性质,探究不同施肥处理下驱动细菌、真菌和古菌群落变化的关键土壤环境因子。结果表明：与全量化肥配施有机肥（M100NPK）相比,化肥减量75%配施有机肥（M75NPK）提高了土壤SOM、TN、NH₄⁺-N和NO₃^--N的含量,化肥减量50%配施有机肥（M50NPK）处理提高了土壤TK和AK的含量。3种施肥处理（M50NPK、M75NPK和M100NPK）显著增加了土壤细菌、真菌和古菌群落的丰度。与M100NPK处理相比,M50NPK和M75NPK增加了细菌群落主要优势菌门中变形菌门（Proteobacteria）和酸杆菌门（Acidobacteria）的相对丰度,而降低了放线菌门（Actinobacteria）和绿弯菌门（Chloroflexi）的相对丰度,同时也增加了真菌群落主要优势菌门中担子菌门（Basidiomycota）的相对丰度,降低了子囊菌门（Ascomycota）的相对丰度;古菌群落主要优势菌门中奇古菌门（Thaumarchaeota）的相对丰度在M75NPK处理呈现增加趋势,在M50NPK处理呈现降低趋势。与不施肥（CK）处理相比,M50NPK、M75NPK和M100NPK增加了土壤细菌和真菌的Shannon指数和Ace指数,而降低了土壤细菌和真菌的Simpson指数,同时也增加了土壤古菌的Simpson指数,但降低了土壤古菌的Shannon指数和Ace指数。可是施肥处理之间Alpha多样性均无显著性差异。土壤细菌、真菌和古菌群落结构组成对不同化肥减量配施有机肥的响应无显著性差异。土壤pH、TP、TN、SOM和AK是导致细菌、真菌和古菌群落结构变化的主要驱动因子。研究结果表明,与M75NPK和M100NPK相比,M50NPK不会改变土壤性质、微生物群落多样性和结构,但可降低过量化肥施用可能带来的环境风险。因此,M50NPK是热带地区蔬菜种植的优化施肥方式。

Soil Microbial Community Characteristics in Tropical Vegetable Soil under Different Chemical Fertilizer Reduction Based on Metagenomic Analysis

To investigate the effects of chemical fertilizer reduction combined with organic fertilizer on the community structure and composition of bacteria, fungi and archaea in a tropical vegetable rotation soil, a field-oriented fertilization experiment was performed in Wenchang, Hainan Island. Metagenomic sequencing technology was used to investigate the differences in the composition, diversity, and structure of the bacterial and fungal communities under different fertilization condition. Furthermore, the main environmental factors driving the changes of soil bacterial, fungal and archaea communities under different fertilization treatments were analyzed in combination with soil chemical characteristics. The results showed that compared with the treatment of organic fertilizer combined with chemical fertilizer (M100NPK), organic fertilizer combined with 75% reduction of chemical fertilizer (M75NPK) increased the content of soil SOM, TN, NH₄⁺-N and NO₃^--N, and organic fertilizer combined with 50% reduction of chemical fertilizer (M50NPK) increased the content of soil TK and AK. The application of M50NPK, M75NPK and M1000NPK fertilization treatments significantly increased the abundance soil bacterial, fungal and archaea. Compared with M100NPK, M50NPK and M75NPK increased the relative abundance of Proteobacteria and Acidobacteria, but decreased the relative abundance of Actinobacteria and Chloroflexi in the dominant bacteria community at the phylum level. Meanwhile, M50NPK and M75NPK increased the relative abundance of Basidiomycota, but decreased the relative abundance of Ascomycota in the dominant fungi community at the phylum level. The relative abundance of Thaumarchaeota, the dominant archaea community at the phylum level, increased in M75NPK treatment, but decreased in M50NPK treatment. For the soil bacteria and fungi, the Shannon and Ace index increased, but the Simpson index decreased after the M50NPK, M75NPK and M100NPK treatment. For the soil archaea, the Simpson index increased, but the Shannon and Ace index decreased after the M50NPK, M75NPK and M100NPK treatment. However, there was no significant difference in Alpha diversity among the three fertilization treatments. There was no significant difference in the response of soil bacteria, fungi and archaea to the application of different chemical fertilizer reduction combined with organic fertilizer. pH, TP, TN, SOM and AK were the main influencing factors driving for the variation in the community structures of bacteria, fungi and archaea. The results showed that compared with M75NPK and M100NPK, M50NPK did not change soil properties, microbial community diversity and structure, but could reduce the environmental risks caused by excessive fertilizer application. Therefore, M50NPK is an optimal fertilization regime for vegetable planting in tropical areas.