潮土细菌及真菌群落对化肥减量配施有机肥和秸秆的响应

为了研究化肥减量配施有机肥和秸秆对华北麦玉轮作田潮土细菌和真菌群落的影响，在天津市宁河区试验基地开展田间定位施肥试验，采用Illumina高通量测序技术比较了5种施肥模式（单施化肥处理，F；化肥减施处理，FR；化肥减量与秸秆配施处理，FRS；化肥减量与有机肥配施处理，FRO；化肥减量与有机肥和秸秆配施处理，FROS）下土壤细菌及真菌群落的组成、多样性和结构差异，并结合土壤理化性质分析，探究不同施肥处理下驱动细菌和真菌群落变化的关键土壤环境因子.结果表明，FRO处理显著提高了土壤SOM含量.FROS处理的TP含量显著高于FRS处理，增加了13.33%.FRO和FROS处理AP含量较其它处理显著增加，NH₄⁺-N含量显著高于化肥处理（F和FR）.各施肥处理土壤中优势细菌门类均为变形菌门（Proteobacteria）、放线菌门（Actinobacteria）、绿弯菌门（Chloroflexi）和酸杆菌门（Acidobacteria），优势真菌门类均为子囊菌门（Ascomycota）.在化肥减量配施有机肥（FRO）的基础上添加秸秆（FROS）显著降低了放线菌门（Actinobacteria）的相对丰度.FRS和FROS处理均显著降低了芽单胞菌门（Gemmatimonadetes）的相对丰度.FROS处理显著提高了浮霉菌门（Planctomycetes）和疣微菌门（Verrucomicrobia）的相对丰度.对于真菌群落而言，有机肥（FRO和FROS）的施入显著提高了子囊菌门（Ascomycota）的相对丰度.与FR处理相比，FROS处理显著降低了被孢菌门（Mortierellomycota）和油壶菌门（Olpidiomycota）的相对丰度，且FRS处理同样显著降低了油壶菌门（Olpidiomycota）的相对丰度.FROS处理的细菌群落Shannon多样性指数显著高于F和FR处理，分别增加了1.26%和1.25%，Chao1指数较F处理显著增加了4.51%，细菌Shannon多样性指数与AP和NH₄⁺-N含量显著正相关（P<0.05）.与FR处理相比，FRS、FRO和FROS处理显著降低了真菌群落Shannon多样性指数，分别达到29.85%、24.94%和25.73%，真菌Shannon多样性指数与AP含量显著负相关（P<0.05）.细菌群落结构在FROS处理下显著区别于F、FR和FRO处理，土壤SM、TP、pH和AP是导致细菌群落结构变化的主要驱动因子；真菌群落结构在FRO和FROS处理下显著区别于F和FR处理，真菌群落结构变化主要受土壤TN、AP和TP的驱动.综上所述，添加有机肥和秸秆改变了土壤理化性质，进而改变了土壤细菌和真菌群落组成，土壤真菌对有机物料的敏感程度高于细菌，细菌和真菌群落结构均受到土壤P的调控，在潮土农业耕作中应引起充分重视.

Response of Bacterial and Fungal Communities to Chemical Fertilizer Reduction Combined with Organic Fertilizer and Straw in Fluvo-aquic Soil

To investigate the effects of chemical fertilizer reduction combined with organic fertilizer and straw on bacterial and fungal communities in fluvo-aquic soil under a wheat-maize rotation system in North China, a field-oriented fertilization experiment was performed at a trial base in Ninghe District of Tianjin. The differences in composition, diversity, and structure of bacterial and fungal communities were evaluated using five fertilization patterns (chemical fertilizer, F; chemical fertilizer reduction, FR; chemical fertilizer reduction combined with straw, FRS; chemical fertilizer reduction combined with organic fertilizer, FRO; chemical fertilizer reduction combined with organic fertilizer and straw, FROS) using Illumina high-throughput sequencing technology. Further, the main soil environmental factors driving the alteration of bacterial and fungal communities under different fertilization treatments were explored in combination with soil chemical analysis. The results showed that adding organic fertilizer (FRO) significantly increased the SOM content. In comparison with the FRS treatment, the TP content in the FROS treatment significantly increased by 13.33%. The AP content increased significantly after applying the FRO and FROS treatment, and it increased by 18.03%-33.45% and 22.69%-38.72%, respectively, as compared to that with the other treatments. The NH₄⁺-N content of FRO and FROS treatments was significantly higher than that of chemical fertilizer treatments (F and FR), which was 2.14 and 2.23 times that of F treatment, and 2.23 and 2.33 times that of FR treatment, respectively. Proteobacteria, Actinobacteria, Chloroflexi, and Acidobacteria were the dominant bacterial phyla for all treatments, with Ascomycota being the dominant fungal phylum. Based on the chemical fertilizer reduction combined with organic fertilizer, the addition of straw (FROS) significantly decreased the relative abundance of Actinobacteria. Under the FRS and FROS treatments, a significant decrease in the relative abundance of Gemmatimonadetes was observed. Moreover, the FROS treatment caused a significant decrease in the relative abundance of Planctomycetes and Verrucomicrobia. As for the fungal community, the relative abundance of Ascomycota was significantly increased under the treatments applying organic fertilizer (FRO and FROS). In comparison with the FR treatment, the FROS treatment significantly decreased the relative abundance of Mortierellomycota and Olpidiomycota, and the FRS treatment also showed a significant inhibitory effect on the relative abundance of Mortierellomycota. The Shannon index of bacterial community of the FROS treatment was significantly reduced by 1.26% and 1.25% in comparison with the F and FR treatments, respectively; the Chao1 index increased by 4.51% as compared with that of the F treatment. The Shannon index of bacterial community exhibited a significantly positive correlation with available phosphorus as well as ammonium content (P<0.05). In comparison to the FR treatment, the FRS, FRO, and FROS treatments significantly decreased the Shannon index of fungal community by 29.85%, 24.94%, and 25.73%, respectively. A significantly positive relationship between the Shannon index of fungal community and available phosphorus content was observed. The community structure of bacteria of the FROS treatment was significantly different from that of F, FR, and FRO treatments, with the soil moisture, total phosphorus, pH, and available phosphorus as the major driving factors; the fungal community structure of the FRO and FROS treatments showed significant difference from that of the F and FR treatments, and the fungal community structure was mainly altered by total nitrogen, available phosphorus, and total phosphorus. In summary, our results indicated that the bacterial and fungal communities in fluvo-aquic soil exhibited a relatively strong response to the chemical fertilizer reduction combined with organic fertilizer and straw; meanwhile, the fungal community was also significantly influenced by chemical fertilizer reduction with organic fertilizer. Therefore, the organic fertilizer and straw drive the changes in the bacterial and fungal community composition, while improving the soil physicochemical properties. The fluvo-aquic fungi were more sensitive to the organic materials than the bacteria. Soil P was a common important influencing factor for regulating the bacterial and fungal community structure, and it should be paid full attention during the agricultural cultivation of fluvo-aquic soil.