Effects of crop rotation and straw return on soil microbiome in a southern paddy field

Crop rotation and straw return are important sustainable agricultural practices.However, their combined impact on the soil microbiota is poorly understood.Here, the effects of crop rotation and straw return on rice (Oryza sativa L.) productivity, soil properties and soil microbial community was investigated in a Chinese southern paddy soil.There were six treatments, including rice-fallow (RF), rice-rape (Brassica campestris L.) rotation (RR), rice-edamame (Glycine max (L.) Merr.) rotation (RE), RF with rice straw return (RFS), RR with rice and rape straw return (RRS), and RE with rice and edamame straw return (RES).The results showed that rice yields in RR and RE were increased by 6.28% and 6.93% relative to RF and straw return group increased by 3.03%-8.16%relative to the group without straw return.Rotation increased soil available P (AP) and RRS significantly increased soil organic matter (OM), total N (TN) and available K (AK) in comparison with RR.Rotation impacts soil microbial community in a stronger way than straw return.Rotation increased the bacterial species numbers and fungal Shannon index.Disease-suppressing bacteria were enriched and some fungal pathogen was decreased in rotation treatments.Straw return had no potential risk in increasing the microbial pathogens.Soil fertilities like AK and AP were closely correlated with bacterial alpha-diversity and rice yield.In conclusion, our research demonstrated that combined crop rotation and straw return is an optimum agricultural practice in increasing rice productivity and soil fertility.The impacts of crop rotation and straw return on the microbiota were distinct.These findings help us manage the crops and residues in southern China.