Deciphering the turnover of bacterial groups in winter agricultural soils.

In winter, snowpack is an important driver of soil bacterial processes. Amending soil through the addition of organic compost has also been reported to affect soil properties and bacterial communities. However, the effects of snow and organic compost on soils have not been systematically researched and compared. To investigate the effects of these two activities on the succession of bacterial communities in the soil and on important soil nutrients, four treatment groups were established in this study: no snow without compost (CK-N), no snow with compost (T1-N), snow without compost (CK-X) and snow with compost (T1-X). Four representative time periods were also selected according to the extent of snow accumulation, including the first snow and melt. In addition, the compost pile was treated with fertilizer made from decomposing food waste. The results indicate that Proteobacteria was more affected by temperature and that fertilization increased its proportional abundance. The abundance of Acidobacteriota was increased by snow. Ralstonia could depend on nutrients provided by organic fertilizers, which prevented them from ceasing to breed at low temperatures, while snow cover was still able to reduce their survival. However, snowpack increased the abundance of RB41. Snow reduced the point and connectivity of the bacterial community and increased the association with environmental factors, especially the negative correlation with total nitrogen (TN); the prefertilizer application made the community network larger while maintaining association with environmental factors. Specifically, more key nodes in sparse communities after snow cover were identified by Zi-Pi analysis. The present study systematically assessed soil bacterial community succession in the context of snow cover and fertilizer application and interpreted the farm environment from a microscopic perspective through the winter. We found that snowpack affects TN through bacterial community succession. This study offers new insight into soil management.