Influence of long-term fertilization on structures of arbuscular mycorrhizal fungi community in a brown soil

Objectives This study aims to explore changes of community structures of AM (Arbuscular mycorrhizal) fungi and to find out main factors of affecting the structures in a corn-soybean rotation system and a long-term fertilization trial for 38 years in a brown soil.

Methods Soil samples (0–20 cm) were taken from six treatments of the long-term fertilization trial in April 2016, 1) no fertilization (CK); 2) chemical N input (N); 3) chemical N and P input (NP); 4) chemical N, P and K input (NPK); 5) pig manure (M); and 6) pig manure plus chemical N and P(MNP). Soil samples were analyzed using PCR-DGGE, cloning and sequencing techniques, and the relationship between community of AM fungi and environmental factors was analyzed using the redundancy analysis and canonical correlation analysis.

Results The results showed that the contents of total organic C (TOC), total N (TN), total P (TP), total K (TK), alkali-hydrolysable N (AHN), available P (AP), readily available K (AK) in the organic fertilizer treatments were significantly higher than those in the CK treatment and chemical fertilizer treatments, and the trend is: organic fertilizer > chemical fertilizer > CK. Compared with the CK treatment, the chemical fertilizer treatments decreased soil pH, while the organic fertilizer treatments increased soil pH. The redundancy analysis showed that pH had significantly negative correlation with the diversity and evenness of AM fungi. AP, TK and AHN had significantly positive correlation with spore density. There was no correlation between AM fungi diversity index with spore density. The cluster analysis showed that the community structures of AM fungi were divided into two groups, namely, non fertilization group and fertilization group, and their similarity was only 42% under the long-term fertilization. The result of sequencing showed that AM fungi species isolated from soil samples were mainly glomeromycota. The canonical correlation analysis showed AP, AK, TOC and NH₄⁺-N significantly influenced the species of AM fungi.

Conclusions The long-term fertilization changed community structures of AM fungi by changing soil physicochemical properties.