UAV Multispectral Imaging for Multi-Year Assessment of Crop Rotation Effects on Winter Rye

Crop rotation is a cornerstone of sustainable agronomy, whereas continuous monoculture can degrade soil fertility and crop vigor. A three-year field experiment (2023–2025) in Lithuania compared winter rye grown in a long-term field experiment of continuous monoculture (with and without fertilizer/herbicide inputs) with five diversified rotation treatments that included manure, forage, or cover crop phases. Unmanned aerial vehicle (UAV) multispectral imaging was used to monitor crop health via the Normalized Difference Vegetation Index (NDVI, an indicator of plant vigor). NDVI measurements at three key developmental stages (flowering to ripening, BBCH 61–89) showed that diversified rotations consistently achieved higher NDVI than monoculture, indicating more robust crop growth. Notably, the most intensive and row-crop rotations had the highest canopy vigor, whereas continuous monocultures had the lowest. An anomalous weather year (2024) temporarily reduced NDVI differences, but rotation benefits re-emerged in 2025. Overall, UAV-based NDVI effectively captured rotation-induced differences in rye canopy vigor, highlighting the agronomic advantages of diversified cropping systems and the value of UAV remote sensing for crop monitoring.