Impact of urease and nitrification inhibitors on nitrous oxide emissions from fluvo-aquic soil in the North China Plain

Little information is available on the effects of urease inhibitor, N-(n-butyl)thiophosphoric triamide (NBPT), and nitrification inhibitor, dicyandiamide (DCD), on nitrous oxide (N2O) emissions from fluvo-aquic soil in the North China Plain. A field experiment was conducted at the Fengqiu State Key Agro-Ecological Experimental Station, Henan Province, China, to study the influence of urea added with NBPT, DCD, and combination of both NBPT and DCD on N2O emissions during the maize growing season in 2009. Two peaks of N2O fluxes occurred during the maize growing season: the small one following irrigation and the big one after nitrogen (N) fertilizer application. There was a significant positive relationship between In [N2O flux] and soil moisture during the maize growing season excluding the 11-day datasets after N fertilizer application, indicating that N2O flux was affected by soil moisture. Mean N2O flux was the highest in the control with urea alone, while the application of urea together with NBPT, DCD, and NBPT + DCD significantly lowered the mean N2O flux. Total N2O emission in the NBPT + DCD, DCD, NBPT, and urea alone treatments during the experimental period was 0.41, 0.47, 0.48, and 0.77 kg N2O-N ha(-1), respectively. Application of urea with NBPT, DCD, and NBPT + DCD reduced N2O emission by 37.7%, 39.0%, and 46.8%, respectively, over urea alone. Based on our findings, the combination of DCD and NBPT together with urea may reduce N2O emission and improve the maize yield from fluvo-aquic soil in the North China Plain.