Field validation of DNDC model for nitrous oxide emission from typical fluvo-aquic soils

The validities of DeNitrification-DeComposition(DNDC) model and the simulation parameters were examined by using field experiment data obtained from typical fluvo-aquic soils at Hengshui experiment station, Hebei Province. The results show that the DNDC model could be well used for simulating the temporal variations of soil moisture and mean daily temperature at soil surface during winter wheat/summer corn growing seasons. There is significantly positive correlation between soil N2O flux and soil moisture (water filled pore space), while the correlation between soil N2O flux and soil temperature is not significant during winter wheat/summer corn growing seasons. The peaks of N2O emission are mainly affected by rainfall and nitrogen application, and the simulated values are relatively close to the measured ones for peaks of N2O emission and its appearance time. It is necessary to modify some parameters of the DNDC model for capturing seasonal N2O emission fluxes precisely. According to sensitivity test on the DNDC model, soil N2O emission is found to be sensitive to the changes of the amount and time of nitrogen application, soil initial inorganic nitrogen content and soil texture, among which the amount and time of nitrogen application are the most sensitive factors. By modifying some parameters based on the local soil properties and management, the DNDC model could become a powerful tool for estimating N2O emission from agro-ecosystem.