Advancing 10-m Crop Mapping Using All Sentinel-2 Observations over the Contiguous United States

High-resolution crop maps over large spatial extents are fundamental to many agricultural applications. However, generating high-quality crop maps consistently across space and time is challenging. In this study, we improved a workflow for operational crop mapping and developed the first openly available, annual, 10-m spatial resolution maize and soybean maps over the Contiguous United States (CONUS) from 2019 to 2022. We obtained all available Sentinel-2 surface reflectance data between May and October for every year, applied quality assurance, corrected the bidirectional reflectance distribution function (BRDF) effects, and generated 10-day composites as the analysis ready data (ARD) product. We then derived multi-temporal metrics from the 10-day ARD as training input for the national-scale wall-to-wall mapping. We conducted annual field surveys and collected ground data based on a stratified, two-stage cluster sampling framework. Utilizing the training data with Sentinel-2 multi-temporal metrics, we trained random forest models generalized for annual maize and soybean classification separately. Validated using field data, our annual maps achieved consistent overall accuracies (OA) greater than 95% with standard errors less than 1%. User’s accuracies (UAs) and producer’s accuracies (PAs) for maize were higher than 91% and 84% across the years, and UAs and PAs for soybean were greater than 88% and 82%, respectively. To illustrate the significant improvement of the 10-m map over existing datasets e.g., the Cropland Data Layer (CDL), we aggregated the 10-m maps to 30-m spatial resolution and quantified the amount of 30-m mixed pixels that can be reduced at field, regional, and national levels. The counties with the most maize and soybean production in Iowa, Illinois and Nebraska had the lowest reduction in mixed pixels, ranging from 1% to 10%, whereas southern counties had higher reduction in mixed pixels. Overall, the median percentages of mixed maize and soybean pixels across all counties were 14% and 16%, respectively, illustrating the substantial benefits of 10-m maps over 30-m maps. With more Sentinel-2-like data available from continuous observations and incoming satellite missions, we anticipate that 10-m crop maps will greatly benefit long-term monitoring for agricultural practices from the field to global scales.

Li, H., Song, X.P., Adusei, B., Pickering, J., Lima, A., Poulson, A.J., Baggett, A., Potapov, P., Stehman, S.V. and Hansen, M. (2024), Advancing 10-m Crop Mapping Using All Sentinel-2 Observations over the Contiguous United States. AGU Fall Meeting, Abstracts GC13O-0407, December 9-13, Washington, D.C., USA.