Enhancing Agronomic Efficiency of Fertilizers in Sub-Saharan Africa: Evidence from the Field

Abstract

While global fertilizer use has significantly increased since the 1960, and played an important role in the Green Revolution in South America and Asia, fertilizer use in Africa has remained very low, near 18 kg nutrients ha-1. Increased use of fertilizers, improved seed, and irrigation in Asia and Latin America have combined to increase cereal yields from 1.3 t ha-1 in the 1960s to above 4.0 t ha-1 in 2009 (Van der Velde et al., 2013). During the same time, average cereal yields in sub-Saharan Africa (SSA) have stagnated near 1.5 t ha-1 while the yield gap, attributed mainly to low and inefficient use of agricultural inputs, remains very high. While smallholder farmers in SSA appreciate the benefits of fertilizers, and African governments have increasingly invested in fertilizer purchases since the 2006 Abuja declaration, access to fertilizer remains severely restricted. Bationo et al. (2004) found that farmers in SSA removed about 4.4, 0.5, and 3.0 million (M) t ha-1 yr-1 of nitrogen (N), phosphorus (P), and potassium (K); while only returning 0.8, 0.3, and 0.2 M t, respectively, and little has changed since then. Hence, soil nutrient mining amounts to five times nutrient application every year. Many factors constrain the use of fertilizer by smallholder farmers and this situation is especially aggravated by the following issues: 1. Access to inputs: Smallholder farmers have limited financial resources and market access to appropriate chemical fertilizers. Fertilizer prices are impacted by long value chains and unregulated markets, particularly in landlocked countries, where prices could double over short distances. Past samples of average prices for urea found them lowest in Ghana (0.80 USD kg-1), Kenya (0.97 USD kg-1), and Nigeria (0.99 USD kg-1), while fertilizers are most expensive in landlocked countries (Burundi: 1.51, Uganda: 1.49, and Burkina Faso: 1.49 USD kg-1; Bonilla Cedrez et al., 2020). Unless strategic and targeted use of fertilizers is employed, the economic returns to investment in fertilizer by smallholder farmers is very poor under the prevailing production and market conditions. The most recent increases in fertilizer prices are already impacting the costs of both inputs and food imports in SSA.