Maize yield gaps and their mitigation in Ethiopia: an integrated assessment

Over the past decade, Ethiopia has achieved the second highest maize yields per hectare in Africa. Yet, maize yields are only 20% of the estimated water-limited potential yield. The major aim of the thesis was to explain actual farmers’ maize yields and maize yield gaps along with the associated technologies and management practices used in maize production in Ethiopia. The study adopted an integrated production-ecological and socio-economic perspective and methodological approach and used large farm surveys from multiple years. First, the thesis provided a national level analysis of maize yield drivers and maize yield gap decomposition into efficiency, resource and technology components. Decomposing the yield gap into efficiency (18%), resource (20%) and technology (63%) components indicates their relevance and can guide policy design and implementation. Second, yield response to fertiliser use was estimated and economic attractiveness of fertiliser usage was evaluated at different levels of assumed risk aversion. Actual nitrogen use rate was far below the agronomic and economic optimum nitrogen levels. However, taking risk into account showed that actual nitrogen use rate was close to economic optimum. Addressing risk along with an improved fertiliser supply chain can improve fertiliser use and its returns. Third, major technologies and management practices in Ethiopian maize production were described and their association with maize yield and labor productivity was investigated. Technologies and management practices were used as complementary and substitutes. However, contrary to expectations, using different technologies and practices in combination did not always lead to higher maize yields, suggesting that they may not be practised optimally and/or not tailored properly to the local conditions.  Fourth, the thesis evaluated the factors that correlate with crop diversity decisions in maize-based systems and assessed the trade-offs between crop diversity and farm outcomes. The positive impact of specialisation on technical efficiency in maize cultivation, and hence income from maize, outweighed the potential positive impact from diversification on the value of production. However, these monetary benefits may come at the expense of higher risks associated with a less diversified crop portfolio. In conclusion, while more in-depth analysis of the management practices and technology implementation by smallholders is clearly needed, the analysis assembled in this thesis strongly indicates that farmers make agronomic management decisions which are informed by economic and other non-agronomic considerations. Profitability and risk seem to be key factors. Agronomic policy and investments may seek to integrate these factors into efforts to improve agricultural productivity through better agronomic practices.