Changes in soil bacterial community and enzyme activity under five years straw returning in paddy soil

摘要

Soil biological properties are essential for sustainable agriculture development. A five-year field experiment was conducted to understand the effects of mineral fertilizers combined with straw returning on bacterial community composition and enzyme activities in paddy soil. Treatments included three fertilizer rates of unfertilized (FO), half and full of conventional mineral fertilization (F1: 138.0 kg N ha(-1) y(-1), 67.5 kg P2O5 ha(-1) y(-1) and 39 kg K2O ha(-1) y(-1) and F2: 276.0 kg N ha(-1) y(-1), 135.0 kg P2O5 ha(-1) y(-1) and 78 kg K2O ha(-1) y(-1)) and combined with (S1: 9.0 Mg ha(-1)) or without straw (SO). Organic matter content increased by 62.8% in S1F1 and 67.2% in 51F2 in the 0-10 cm soil compared to S0F0. Compared with S0F0, S1F0 treatment increased the soil available nitrogen (AN), phosphorus (AP) and potassium (AK) content by 8.8% 9.7% and 30.0%, respectively, in 0-10 cm soil. The soil phosphatase, urease and invertase activities were increased with straw returning. The treatments of S0F1 and S0F2 reduced the soil phosphatase and invertase activities. Compared with S0F0, the S1F2 treatment significantly decreased bacterial diversity, while the S1F1 alleviated the decrease of soil bacterial diversity. Bacterial of Proteobacteria, Acidobacteria and Chloroftexi were the dominated phyla, and RDA identified that soil AN and SOM were closely correlated with bacterial community composition in both 0-10 cm and 10-20 cm soil, respectively. The higher carbon:nitrogen ratio was also observed in the S1F1, which was better for bacterial diversity. Overall, the continuous application of straw with mineral fertilizer improved soil enzyme activities and altered soil bacterial community composition. This suggests that the bacterial community respond differently to the long-term straw returning combined with mineral fertilization, which may result from different effects of C and N content or C: N ratio of soil on the composition of bacterial community.