An act of defiance? Measuring farmer deviation from personalised extension recommendations in Zambia

Given the recognised role of blanket extension advice in the low uptake of productivity‐enhancing technologies among developing country farmers, personalised or site‐specific extension approaches are gaining attention. Focusing on the case of the plant clinic extension model which provides personalised crop protection services to smallholder farmers, we investigate to what extent and how accurately farmers adopt personalised extension advice, and the implications for agricultural productivity. We combine a unique database of personalised integrated pest management (IPM) recommendations provided to 420 plant clinic attendees in Zambia with survey data on the actual IPM practices implemented by these same clinic attendees. We find that more than 80% of the sample farmers deviated from the personalised IPM recommendations they received from plant clinics. Based on the degree of deviation from the personalised recommendations, we identify five categories of adopters of IPM practices and show their heterogeneous effects on maize productivity. For example, our multi‐valued treatment effect estimates suggest an 82% yield penalty for non‐adopters compared to full adopters of recommended IPM practices, while the yield gain for full adopters is more than double that of partial adopters, as well as that of those who adopted additional practices beyond what was recommended. Our findings have important implications for the promotion of personalised extension services and for the measurement of the impact of complex agricultural technologies.