Biomass crops, such as willow, are often characterized by low shoot density and high variability in yield and biomass quality parameters. To deliver reliable information on crop production and biomass quality aspects, the adoption of an appropriate sampling area and method are essential. The current study investigated the optimal sampling area required for willow to determine dry matter yield and quality characteristics with variability ≤10%. For this purpose, whole plots of willow were divided into 1-m² subplots and harvested to determine fr...