Modeling of Maize Yield Response to Biochar Application in Ghana.

Biochar is currently being considered as an important agricultural resource in sub-Saharan African countries where its application to soils can alleviate the decline of soil fertility due to agricultural intensification while improving crop productivity, soil performance, and greenhouse gas balance. Recent field experiments in Ghana indicated noticeable increases of maize yields likely associated with improved water hold capacity when biochar was applied along with chemical fertilizers. In order to investigate such relationship between water holding capacity enhanced by biochar application and corresponding maize yields, we utilized a process-based model for cropping systems - Decision Support System for Agrotechnology Transfer (DSSAT) model – coupled with an automatic calibration algorithm – Shuffled Complex Evolution method. We first calibrated the model’s parameters related to soil initial conditions and maize cultivars using yield records from 18 fields under farming practices with or without NPK fertilization. Then we calibrated and validated the model’s coefficient controlling water holding capacity of residue added to soils using yield records under biochar application. This type of work will permit DSSAT model to predict maize yield response to various biochar application rates in Ghana that can further link to policy and econometric models.