Influence of inorganic fertilizer and organic manure application on fungal communities in a long-term field experiment of Chinese Mollisols

The effects of 35 years of manure amendment on fungal communities were evaluated in Mollisols of northeast China. Soil samples from different fertilization regimes were collected, and quantitative PCR analysis of fungal community size and Illumina platform based analysis of the ITS gene were performed to characterize soil fungal abundance and compare community structure and diversity. The treatments were no fertilizer (CK); manure (M); nitrogen, phosphorus and potassium inorganic fertilizer (NPK); and inorganic fertilizer plus manure (MNPK) regimes. Soil fungal diversity was decreased by inorganic fertilizer. Inorganic fertilizer plus manure induced a weak increase in fungal diversity and a slight decrease in size. The predominant phyla were Ascomycota (63.77–78.70%), Zygomycota (8.33–14.80%) and Basidiomycota (4.03–13.47%). At each taxonomic level, the percentages dramatically differed, especially between MNPK and NPK. For example, the numbers of Fusarium and Gibberella with potential pathogenicity were all higher in NPK than in MNPK; the beneficial genus Podospora was the highest in MNPK and the least in NPK. Principal coordinates analysis showed that CK and M were clustered together; the incorporation of NPK with manure improved the fungal structure near to that of CK and separate from that of NPK. Redundancy analysis indicated that fungal community structure was most affected by soil available phosphorus (AP) and organic matter contents, followed by soil pH. Simpson and Shannon indices were closely correlated with soil pH, AP, total phosphorus and total nitrogen. The results indicated that manure application altered soil properties and soil fungal community structure, and manure with inorganic fertilizer counteracted some of the adverse effects of the inorganic fertilizer.