Economic efficiency and stage-level loss elasticity of the maize ( Zea mays L.) postharvest system in Zambia

Understanding how postharvest losses (PHL) respond to economic and production dynamics across value chain stages is critical for targeted interventions. This study estimates stage-level loss elasticities in Zambia’s maize (Zea mays L.) postharvest system using a 23-year dataset (2000–2022) across six value chain stages: harvesting and field drying, further drying, threshing and shelling, transport from the field, household level storage, and transport to the market. An Autoregressive Distributed Lag (ARDL) error correction framework is employed to estimate short- and long-run PHL dynamics guided by five hypotheses: yield-induced efficiency, price-driven loss mitigation, development-path loss modulation, production shock transmission, and a structural break associated with the 2008 global food price crisis. Findings show marked heterogeneity across stages; Income growth reduces losses in mechanizable stages (e.g. threshing/shelling: β = −0.525, p < 0.001) but increases losses in market-exposed stages (e.g. transport to market: β = 0.615, p < 0.001), revealing a structural divergence between mechanization gains and commercialization challenges. In the short-run, production shocks significantly exacerbate losses (elasticity = 0.801, p < 0.001), indicating binding capacity constraints. Counterfactual simulations indicate that a 5% PHL reduction would save about 19,059 tonnes annually (∼USD 4.57 million), with cumulative caloric recovery sufficient to feed approximately 2.8 million people. These findings challenge uniform intervention approaches and highlight the need for stage-specific, economically informed investment strategies.