RTSI: An Analytical Radiative Transfer Model for Strip-Intercropping Systems

Strip-intercropping systems present challenges for radiative transfer modeling due to the complex mutual shadowing between alternating tall and short crops. To address this, we developed an analytical Radiative Transfer model for Strip-Intercropping (RTSI), validated against UAV observations and 3D simulations in a maize-soybean system. The model demonstrated high accuracy in capturing canopy reflectance (R²≥0.94, RMSE<0.0251). Sensitivity analysis confirmed RTSI's robustness (RRMSE<8%) across varying configurations, significantly outperforming the Spectral Linear Mixture (SLM) model, which produced large errors in heterogeneous scenarios. Furthermore, the study elucidated the role of multiple scattering in compensating for energy in shadowed regions, effectively reshaping bidirectional reflectance anisotropy. RTSI serves as a vital tool for analyzing light transport and supporting the precise retrieval of biophysical parameters in complex intercropping systems.