Effect of different long-term fertilization regimes on the viral community in an agricultural soil of Southern China

• Long-term different fertilization changed soil viral abundance.
• Organic fertilization increased soil organic matter and pH value.
• Organic fertilization increased soil viral abundance and morphological diversity.

Fertilization plays a pivotal role on soil biological process and affects the soil bacterial community, which act as hosts for viruses. The effect of fertilization on soil viral community has not been well explored. In this study, a Haplic Acrisol soil, which is the soil type for 13 provinces in Southern China, was analyzed after 22 years different fertilization regimes for their viral composition. The soil responded to organic fertilizations with an increased amount of soil organic matter (SOM) and pH (increased from 5.7 to 6.6), while with the decreased SOM and pH for chemical fertilization, especially for single nitrogen fertilization. The combined effects of SOM and pH caused by long-term different fertilization regimes on soil viral communities were investigated by direct calculation of virus-like particles (VLPs) through epifluorescence microscopy. The highest VLP abundance (13.1 × 107 per gram dry soil) was detected in soil applied with chemical and organic fertilizers. The viral and bacterial abundances of organic soil were 4 and 5 times higher than those of inorganic soil respectively. Transmission electron microscopy observation revealed a higher frequency of Myoviridae viruses in soil with organic amendments than without organic amendments, and vice versa for Podoviridae viruses. These results demonstrate that organic fertilizer could increase viral abundance and morphological diversity through suppressing soil acidification and improving soil organic matter.