The potential of active and passive remote sensing to detect frequent harvesting of alfalfa

•First attempt to use satellite-based C-band radar in detecting alfalfa harvesting.•Evaluated multiple active and passive RS datasets in detecting alfalfa harvest.•Combined Landsat and Sentinel-2 observations to increase temporal resolution.•Investigated the role of radar incident angle in detecting alfalfa harvest.•Evaluated the sensitivity of various remote sensing datasets to alfalfa harvest.