Long-term moderate carbon input benefited arbuscular mycorrhizal fungal community diversity and vitality in a sandy loam soil

Soil arbuscular mycorrhizal (AM) fungi play crucial roles in facilitating agroecosystem functioning. However, little is known about their performances in either community composition or ecological function as affected by fertilization with different carbon (C) input levels. Here, an eight-year field experiment established in a sandy loam soil at Northern China, including four treatments of non-fertilization (Control), and NPK-balanced fertilization with no C (F), with relatively low C input level (LCF), and with relatively high C input level (HCF), was adopted to assess soil AM fungal community composition using the Illumina sequencing. Ten genera with the dominance of Glomus followed by Paraglomus and Claroideoglomus were identified, and the communities varied significantly between control and fertilized soils. Long-term fertilization, notably LCF and HCF, increased soil AM fungal diversity, alkaline phosphatase (ALP) activity, and glomalin-related soil protein (GRSP) concentration, which were closely correlated to soil organic C and/or pH. In addition, LCF rather than HCF significantly increased both Chao1 and Shannon indices of AM fungi relative to F, while HCF rather than LCF significantly decreased not only the mycorrhizal colonization relative to control but also the ratio of total GRSP to soil organic C relative to F, suggesting that LCF is better with respect to promoting AM fungal diversity and maintaining their ecological vitality. Our study demonstrated the great value of moderate C input in conserving soil AM fungi and exploring their services.

Automated summary

Soil arbuscular mycorrhizal (AM) fungi play crucial roles in agroecosystem functioning. However, the effects of different carbon input levels on AM fungal community composition and ecological function are not well studied. This eight-year field experiment showed that fertilization significantly influenced the composition of AM fungal communities. Long-term fertilization increased AM fungal diversity, alkaline phosphatase activity, and glomalin-related soil protein concentration, which were closely related to soil organic C and/or pH. Moreover, low C input level (LCF) was better at promoting AM fungal diversity, while high C input level (HCF) negatively affected mycorrhizal colonization and the ratio of total glomalin-related soil protein to soil organic C.