The effects of CO2 database on a localized AquaCrop model construction based on the field experiment

To examine whether the use of default CO 2 database affected the simulation results, this paper built the AquaCrop models of winter wheat based on the measured CO 2 database and the default CO 2 database, respectively. The models were calibrated with data (2017–2018) and validated with the data (2018–2019) in the North China Plain. The residual coefficient method (CRM), root mean square error (RMSE), normalized root mean square error (NRMSE) and determination coefficient (R 2 ) were used to test the model performance. The results showed that the accuracy of simulation under the two CO 2 database were both good. Compared with the default CO 2 database, the simulation accuracy under the measured CO 2 database had higher accuracy. In order to verify the model further, the simulated values of evapotranspiration, soil water content and measured values were compared and analyzed. The results showed that there were some errors between the measured evapotranspiration and the values of simulation in the filling and waxing period of winter wheat. In general, the simulation values of evapotranspiration were consistent with the measured value at different irrigation levels. The simulated values ​​of the soil water content at the three levels of irrigation were all higher than the measured values, but the simulated results basically reflected the dynamic changes of soil water content throughout the growth period. The model adjustment value of WP*(the normalized water productivity) were a difference under the two CO 2 databases, which is one of the reasons for the difference in the simulation results. The results show that in the absence of measured CO 2 data, the default CO 2 database can be used, which has little influence on the model construction, and the accuracy of the model constructed meets the actual demand. The research results can provide a basis for the establishment of crop models in North China Plain.