RESUMO
Aiming at the problems of excessive and unreasonable fertilizer application, lower nitrogen use efficiency, increasing N2O emission from soil and fertilizer in current intensified agricultural productions, a field experiment was conducted to study the effects of dicyandiamide (DCD) combined with nitrogen fertilizer application at different levels, i.e., 150, 225, 300 kg . hm-2, on N20 emission and relevant economic benefit in a typical winter wheat-summer maize rotation system in North China Plain. The results showed that DCD application decreased N2O emission fluxes and cumulative emissions by 25.6%-32.1% and 23.1%-31.1% in the year-round. There was a significant positive exponential correlation between N2O flux and soil surface temperature or soil moisture content. The effect of soil moisture on N2O emission was stronger in wheat season than in maize season, while the effect of temperature on N2O emission was on the contrary. The yields of winter wheat and summer maize with DCD addition were increased by 16.7%-24.6% and 29.8%-34.5%, respectively, and the average economic income of two seasons was increased by 7973.2 yuan . hm-2. Therefore, appropriate rate of N fertilizer combined with DCD could not only increase crop yield and economic income, but also reduce N2O emission. Considering environmental and economic benefit under this experimental condition, DCD combined with nitrogen of moderate level (total N amount 225 kg . hm-2) was a good nitrogen management mode in North China.