Impact of long-term fertilization on soil bacterial community

The addition of organic matters was considered to be a feasible practice to mitigate soil degradation and environmental problems caused by long-term application of chemical fertilizers. However, how different organic matters impact soil bacterial community and the correlations between soil bacterial community and crop yield are not clear. In the present study, we analyzed the shifts of soil bacterial community under long-term (32 years) application of chemical fertilizers and with different organic matters (wheat straw, pig manure and cow manure) addition. The application of NPK chemical fertilizers induced dramatical change of soil bacterial community structure and lowered its diversity significantly. The addition of wheat straw had no help for bacterial community structure recovery and reduced even much lower bacterial diversity. But the addition of manures could promote the recovery of bacterial community structure and diversity. Analysis revealed that the shifts of soil community structure and diversity were associated with the changes of soil pH. While bacterial abundance and crop yield was associated with soil nutrients level (e.g., nitrate nitrogen, total nitrogen, total carbon, available P). And there is no significant correlation between crop yield and soil bacterial community structure or diversity. These results indicate the addition of livestock manure is not only suitable for agricultural production, but also beneficial to agro-ecological stability. It also suggested that pH may be the key factor impacting not only bacterial distribution, but also bacterial community succession.