Effects of nitrogen on soil nutrients and bacterial community structure in peanut field with wheat straw returning during podding stage.

To investigate the effect of nitrogen on soil nutrients and microbial communities in peanut field with wheat straw returning under wheat peanut rotation mode, four nitrogen levels (N: 0, 45, 90, and 180 kg/hm²) were set to study the soil nutrient content, soil enzyme activity, soil bacterial community structure and diversity during podding stage. The results showed that under the same nitrogen level, straw returning increased soil nutrient content and soil enzyme activity in peanut field at pod setting stage. Compared to the corresponding nitrogen level, the increase of total nitrogen content and total carbon content in soil with straw returning were 12.8%-23.1% and 20.9% -35.4% respectively, and the increase of microbial biomass carbon and nitrogen content were all higher than 48.3%. Wheat straw returning also affected the relative abundance of bacteria in phylum level and the function of bacteria. Under wheat straw returning conditions, the soil microbial carbon and nitrogen content, soil enzyme activity, and peanut yield all showed a trend of first increasing and then decreasing with the increase of nitrogen application rate. Under 45 kg/hm² nitrogen level, the microbial biomass carbon and nitrogen content were highest, the activities of invertase and cellulase were highest, the soil bacterial richness index was high, and the relative abundance of Proteobacteria and Acidobacteria was most affected by wheat straw returning. Addition, there was no significant difference in soil total nitrogen, total carbon content, and peanut yield between 45 and 90 kg/hm2 nitrogen level. Correlation analysis showed that the composition of soil bacterial community of each treatment was affected by the soil total nitrogen, total carbon, ammonium nitrogen, and microbial biomass carbon and nitrogen content. The results indicate that wheat straw returning and nitrogen application not only affect the soil nutrient content and soil enzyme activity, but also affect the composition of soil bacterial community during peanut pod setting stage. Under the condition of wheat straw returning, the nitrogen application of 45 kg/hm² can not only ensure stable peanut yield, but also increase the microbial biomass carbon and nitrogen content in soil during the pod setting stage and improve the soil micro ecological environment. Therefore, the amount of nitrogen fertilizer application can be reduced in the production of peanut with wheat straw returning. [ABSTRACT FROM AUTHOR]