Simulating the Impact of Conservation Agriculture On Corn Yield in the Philippines Using the DSSAT Ceres-Maize Model.

This study aimed to predict the effect of conservation agriculture in terms of changes in soil organic carbon and total soil nitrogen on corn yield in the Philippines using a crop model. The DSSAT-CERES Maize model was calibrated and validated in an experimental site of SANREM-CRSP in Claveria, Misamis Oriental, Philippines under conservation agriculture production system and conventional plow-based system. An optimized step-wise procedure approach was used by setting up boundaries for each coefficient and specifying a constant interval for each coefficient. Optimized values were selected based on minimum RMSE and RRMSE, high d-index, R² and model efficiency (EF). The optimized values obtained are P1 = 270 GDD, P5 = 790 GDD, G2 = 850, G3 = 7.5 mg/ kernel per day, PHINT = 38.9 GDD and SLPF =1 under conventional plow-based system and SLPF = 0.9 under conservation agriculture production system. Validation of the model gave good estimates of silking and maturity dates, maximum LAI, yield and above ground biomass. The effect of conservation agriculture production system on corn yield was reflected by increasing the amount of soil organic carbon (OC) and total soil nitrogen (TN) of up to 30% on both variables. Simulation results showed that the highest positive percent relative crop yield changes of 10.2% and 5.5% were observed under a scenario with a 30% increase OC and 30% increase TN for August to December and December to April cropping periods, respectively. For the plow-based system, results showed that highest negative percent yield changes of 28.5% and 24.4% were observed under a scenario with 30% decrease OC and 30% decrease TN for August to December and December to April cropping period, respectively. These simulation results indicate that long term practice of conservation agriculture production system would result to corn yield being comparable or better than the yield obtained under conventional plow-based system.