Wind-induced fertilizer deposition heterogeneity in sugar beet (Beta vulgaris L.) production: A CFD-DEM coupling study

Precise nitrogen management is critical for balancing the root biomass and sucrose purity of industrial sugar beets ( Beta vulgaris L.). As the working width of centrifugal spreaders increases, fertilizer particles become highly susceptible to wind fields, impairing distribution uniformity. Such nitrogen heterogeneity may increase the risk of localized luxury N uptake and impurity accumulation, which may pose risks to sucrose extractability and downstream processing efficiency. This study aims to identify configuration-specific aerodynamic operating boundaries and assess their potential relevance to sugar beet production. However, systematic research on the dynamic response mechanisms of particle swarms under multi-directional winds—especially oblique winds—remains limited. In this study, a one-way computational fluid dynamics and discrete element method (CFD-DEM) coupled model was developed to evaluate the kinematics and ground distribution of controlled-release urea particles under five wind directions and varying wind speeds. The results demonstrated that the coefficient of variation ( Cv ) reached 47.50% and 46.18% under 6 m·s⁻¹ crosswind and tailwind conditions, respectively. Such substantial distribution variance far exceeds the agronomic tolerance threshold ( Cv ≤ 30%), increasing the risk of localized nitrogen over-application and luxury-consumption zones. By analyzing the reconstruction of the aerodynamic drag field on particles under oblique winds, we defined a "zero-drag effect boundary" and established a 3 m·s⁻¹ critical wind speed threshold for safe operation. This configuration-specific threshold provides a practical reference for identifying wind conditions associated with increased deposition nonuniformity. Such heterogeneity may affect local nitrogen availability and pose potential risks to sugar beet growth and processing quality, although these effects were not directly measured in this study and require field validation.