Contrasting effects of long-term fertilization on the community of saprotrophic fungi and arbuscular mycorrhizal fungi in a sandy loam soil.

The changes of saprotrophic fungi (SF) and symbiotic arbuscular mycorrhizal fungi (AMF) in response to different fertilizers were investigated in a period of 21 years. Denaturing gradient gel electrophoresis profiles showed fungal community structure significantly changed after long-term fertilization. Long-term organic and mineral fertiliza tion significantly increased the SF diversity, whereas mineral fertilization decreased the AMF diversity. SF quan tity significantly increased in response to organic fertilizers, whereas the AMF propagules were down-regulated by nutrient-rich fertilization but induced by N, P or K-deficiency. Redundancy analysis showed that long-term fertilization differentially affected diversity and quantity of SF and AMF. Nutrient-rich organic fertilizers, resulting in higher contents of soil organic C (SOC), total N and mineral N, total and available P, regulated the quantity and diversity of SF positively and quantity of AMF negatively, respectively. The diversity of AMF was slightly downregulated by SOC, total and mineral N and total P as well as the nutrient-rich mineral treatments, in contrast to the positive effects by available K and P. These results indicate that soil nutritional status and fertilizer types signifi cantly affect SF and AMF. Our study of soil fungal community in response to the long-term fertilization can provide new strategies for agronomic practice.