Rational utilization of urease and nitrification inhibitors improve the ammonia-oxidizing bacteria community, nitrogen use efficiency and peanut growth

Peanuts (Arachis hypogaea L.) is an important oil and nitrogen (N) fixing crop. Urease inhibitors (UIs) and nitrification inhibitors (Nis) can mitigate the release of N and reduce the harmful effects of excessive N concentrations. However, the effect of these inhibitors on the soil nutrient-microbial activity-plant growth system is unknown in peanut. The purpose of this study was to investigate the effects and mechanism of N-(n-butyl) thiophosphoric triamide (NBPT), 3,4-dimethylpyrazole phosphate (DMPP) and sulfur-coated urea (SCU) on peanut. The results showed that comparing with urea alone, adding NBPT + DMPP inhibited the urea hydrolysis better and decreased the concentration of NH4+-N + NO3−-N by 20.8% in soil. Therefore, it increased the net photosynthetic rate, promoted the development of roots even the absorption of N by peanut, with N use efficiency (NUE) up to 20.8%. The effect of NBPT + DMPP on microorganism was better than that of NBPT alone, which considerably impacted the structure and abundances of aonia oxidizing bacteria (AOB) but not ammonia-oxidizing archaea (AOA). Specifically, g_Nitrosospira and g_Nitrosomonas decreased by 46.9% and 2.2% respectively, and g(c) Betaproteobacteria increased. Furthermore, when combined with SCU on this basis, the overall effect was clearer.