Establishing and assessing a new two-dimensional module in CERES-maize for maize production under mulched drip irrigation

Abstract

In view of the problem that the traditional CERES-maize model does not consider plastic film covering and the water balance module describes a one-dimensional movement of soil water, this study modified the input data of air temperature, which was compensated by the soil accumulative temperature under plastic film mulching, based on the invariance of growing degree days principle in the model, and established a two-dimensional (2D) CERES-Maize model. The 2D model was calibrated and verified with maize phenological period, aboveground biomass (AB), grain yield and yield components, and maize actual evapotranspiration (ET_{c act}) during the whole growing season in 2015 and 2016 under mulched drip irrigation. Results indicated that the modified model effectively improved the simulating accuracy of maize phenological period and main growth indexes, which made the Absolute Relative Error (ARE) decrease by 11.2 %, 1.8 % and 2.1 % points for maize emergence, anthesis and maturity date respectively, and made the normalized Root Mean Square Error (nRMSE) reducing 1.5 % and 5.9 % points for grain number per ear and AB respectively, due to the compensation of soil temperature under film mulching for the air temperature during maize Sowing∼V6 (the sixth leaf) period. The 2D CERES-Maize model was established with a consideration of plastic film mulching effect on soil water evaporation and the two-dimensional water movement characteristics of drip irrigation. The simulating accuracy of 2D model was improved with a decrease of 1.5–2.5 % and 2.5–4.8 % points in nRMSE for grain yield and AB, respectively, compared with those of 1D model. The 2D model could simulate the differences of maize ET_{c act} during the whole growing season under different irrigation quotas very well (nRMSE<10 %), and the simulating accuracy of 2D model was significantly improved with a decrease of 2.2–5.9 % points of nRMSE for maize ET_{c act}, compared with that of 1D model. In conclusion, the 2D CERES-Maize model preliminarily established in this study basically realized the simulation of maize production under mulched drip irrigation, but how to consider the warming effect of plastic film mulching in the model remains to be further improved.