The Response of Maize to N Fertilization in a Sub-humid Region of Ghana; Understanding the Processes Using a Crop Simulation Model

Abstract

Crop simulation models afford the opportunity to study and understand underlying processes that impact on crop yield, hence, helps in designing appropriate strategies to improve crop production. The response of maize to N fertilization in a sub-humid environment was evaluated using DSSAT (crop simulation model). Two field experiments were conducted in the major and minor seasons in 2007. One was conducted under limited water and nutrient stress conditions and data collected used to calibrate model. The second independent experiments were conducted with different levels (0, 40, 80 and 120 kg N ha–1) of N fertilizer. Grain and biomass yields were predicted with an index of agreement of between 0.64 and 0.95 in both major and minor seasons. Biomass N content and crop phenology were also adequately simulated. Model simulations were better with higher rates of N fertilization and lesser water stress conditions. Water stress during the reproductive stage significantly affected grain yield. Sensitivity of selected soil parameters to grain yield indicated more sensitivity when no N fertilizer was applied. The DSSAT model has been satisfactorily calibrated and evaluated for the study area and hence, can be used to aid decision making in respect of farm management options.