Soil bacterial community composition in rice-fish integrated farming systems with different planting years.

The high productivity and efficient nutrient utilization in rice-fish integrated farming system are well reported. However, the characteristics of soil bacterial communities and their relationship with soil nutrient availability in rice-fish field remain unclear. In this study, we selected three paddy fields, including a rice monoculture field and two rice-fish fields with different planting years, to investigate the soil bacterial community composition with Illumina MiSeq sequencing technology. The results indicated that the soil properties were significantly different among different rice farming systems. The soil bacterial community composition in the rice-fish field was significantly different from that in the rice monoculture field. Five of the top 15 phyla were observed with significant differences and Nitrospirae was the most significant one. However, no taxa observed with significance between the rice planting area and aquaculture area no matter in the 1st or 5th year of rice-fish field. RDA analysis showed that the soil bacterial community differentiation in the 5th year of rice-fish field was positively correlated with soil properties, such as AN and OM contents, EC and pH value. Although the rice yields in rice-fish field decreased, the net economic benefit of the rice-fish system enhanced obviously due to the high value of aquaculture animals.