How Demonstration Farms Drive Adoption: Evidence from a 20-Year Scoping Review and Dynamic Payback Analysis

Demonstration farms remain one of the most widely used but unevenly evaluated approaches to agricultural extension. This paper synthesizes evidence from a 20-year scoping review of 57 demonstration-farm interventions conducted between 2005 and 2025 across Sub-Saharan Africa, Southeast Asia, and Europe. Rather than estimating a single pooled effect size, the review maps patterns in yield response, adoption, institutional continuity, and economic performance across heterogeneous contexts. Median yield gains among participating farmers clustered around the mid-teens, with adoption typically increasing over successive seasons as peer observation and local credibility accumulated. To evaluate economic performance over time, the study applies Return on Investment (ROI) and a Dynamic Payback Analysis (DPA) that models cumulative farmer benefit against cumulative program cost across cropping seasons. Results indicate that demonstration farms tend to reach economic break-even within approximately 2–3 seasons, earlier where local governance and in-season troubleshooting support are present. The findings suggest that demonstration farms function less as short-term training events and more as durable learning infrastructure, generating compounding agronomic and economic benefits when embedded in local institutions. The analysis has implications for extension design, evaluation timelines, and funding strategies that seek sustained adoption rather than short-term reach. Keywords: Farms Drive, Adoption, 20-Year Scoping, Dynamic Payback, Analysis