Quantifying yield gaps and agronomic drivers of potato productivity in Bhutan

Potato ( Solanum tuberosum ) is a vital crop for food security and livelihoods in Bhutan, yet its productivity has declined, with a national average yield (11.8 t ha⁻¹) severely lagging behind regional and global benchmarks. This study employed a mixed-methods approach to quantify the yield gap for two popular varieties, Desiree and Yusi Maap, and identify key influencing factors. Significant yield gaps of 41% and 52% were found, respectively. The Classification and Regression Tree (CART) model identified seed source as the primary driver; using certified seeds boosted yields to 20.7 t ha⁻¹ compared to 12.3 t ha⁻¹ with self-saved seeds. Other critical factors included soil type, access to agricultural services, and weed management, where weeding twice increased yields by 50%. The findings underscore the need for improved seed systems, targeted agronomic training, and enhanced input access to close yield gaps and promote the sustainable intensification of potato farming in Bhutan.