Effects of long-term different fertilization on soil fungal communities in black soil based on the Illumina MiSeq platform

Abstract:

[Objective] Soil environmental problems caused by irrational fertilization are gradually becoming one of the important factors that restrict the sustainable development of agriculture in China. Soil fungi is a kind of important microorganisms in soil. Hence, it is significant to study the diversity and community distribution patterns of soil fungi under long-term fertilization and investigate the physical and chemical factors on the fungal community structure.[Methods] The black soil under the long-term fertilization experiment (1984-2017) in the northeast of China was adopted to be analyzed by routine analysis and Illumina MiSeq high-throughput sequencing. And then, the effects of long-term fertilization on soil nutrient contents and fungal community structures in black soil corn fields were studied.[Results] The results showed that the long-term application of nitrogen fertilizer significantly decreased pH in soil, but increased the yield of maize. The combined application of straw and fertilizer can increase the content of soil organic matter and total nitrogen. The results of operational taxonomic unites (OTU) curves showed that the long-term fertilization reduced the abundance and evenness of soil fungal sequences, and there was the lowest sequence number in the combined application of straw and fertilizer. Among the dominant communities, it has been found a total of five known fungal Phylum, Ascomycota, Basidiomycota, Zygomycota, Glomeromycota, Chytridiomycota. Among of them, Ascomycota accounted for not only 57.0% in the average of the total sequence, but also 70.35% in the soils with Fertilizer add high amount of straw treatment (NPK+S0.5). In the analysis of species abundance in soil fungal genus level, it has detected 109 known fungi. Humicola, Fusarium, Verticillium and Mortierella were the dominant genus. In addition to that, it was found that the abundance of Chaetomium, Trichocladium, Podospora and Preussia were high in the combined application of straw and fertilizer, and it all belong to a branch cluster. According to the analysis of diversity index, it can suggest that the combined application of straw and fertilizer can increase species abundance and community diversity. According to the Heatmap analysis, it can indicate that there were obviously different in the fungal community between the nitrogenous and non-nitrogenous fertilizers. In Redundancy analysis (RDA), the soil physical and chemical properties affected the community structure of soil fungi, especially soil pH, total nitrogen, total phosphorus and total potassium (TN, TP, TK), available phosphorus and available potassium (AP, AK) and ammonium nitrogen (NH₄⁺-N) is an important environmental factor.[Conclusion] The application of nitrogen fertilizer increased the yield. however, it caused soil acidification. Meanwhile, the application of nitrogen fertilizer increase the number of fungi, but the richness and diversity of fungi was decreased. Nevertheless, the combined application of straw and fertilizer can maintain soil healthy ecological environment and fungal community diversity.