System Dynamics Modelling of Maize Production under Future Climate Scenarios in Kaduna, Nigeria

Nigeria is the second largest producer of maize on the African continent with more than 5 million hectares of land under maize production and an annual area and yield growth rate of 4.1 % and 2.7% respectively (Beyene et al., 2016). However, maize yields in sub-Saharan African countries, including Nigeria, remain low compared with global averages. Yields may be further impacted by shifts in temperature and rainfall under climate change in the coming several decades, given that most maize in Nigeria is rainfed. We used a system dynamics model combined with stakeholder input to simulate maize production in Kaduna state, Nigeria, under a range of scenarios including 1) adoption of hybrid early maturing maize varieties; 2) optimal fertilizer use; and 3) shifts in climate regimes. System dynamics modeling is a technique which allows researchers to investigate the future state of a complex system with both social and ecological components. Our goal with this model was not to replicate the accuracy of yield prediction generated by data-intensive agronomic models, but to build a tool for supporting policy decisions in the region while incorporating socio-ecological dynamics and stakeholder insights. Overall, the model suggests that agricultural policies with respect to maize production should focus on developing and disseminating knowledge and accessibility of early maturing /drought tolerant maize varieties alongside efforts to promote more efficient integrated fertilizer management strategies (such as mixed organic and conventional fertilizers) which increase the agronomic use efficiency of EM hybrid maize varieties. However, even under these optimal efforts to improve maize production in the face of climate change, maize productivity is expected to first rise, and then decline by mid-century under expected precipitation and temperature shifts, demonstrating an inverted U-shaped curve. In the context of a growing population, and therefore a growing demand for food, in Kaduna and in Nigeria more broadly, the results of this study imply the need for a diversification of the agricultural sector towards staple crops that will be less climate-sensitive than maize. This is consistent with other recent agronomic modeling work in sub-Saharan Africa which has found that climate change could severely impact staple food crop production, even under scenarios of technological advancement and fertilizer use (Ittersum et al. 2016; Sulser et al. 2014).