Remote sensing for crop mapping: A perspective on current and future crop-specific land cover data products

Crop mapping is an indispensable application in agricultural and environmental remote sensing. Over the last few decades, the exponential growth of open Earth Observation (EO) data has significantly enhanced crop mapping and enabled the production of detailed crop-specific land cover data at national and regional scales. These data have served multiple purposes across a wide range of applications and research initiatives. However, there is currently no comprehensive summary of the crop mapping data products, nor is there a detailed discussion of their uses in remote sensing studies. This paper provides the first in-depth review of remote sensing for crop mapping from the perspective of crop-specific land cover data by evaluating over 60 open-access operational products, archival crop type map datasets, single-crop extent map datasets, cropping pattern datasets, and crop mapping platforms and systems. Using the Cropland Data Layer (CDL) – one of the most widely used products with over 25 years of continuous monitoring of U.S. croplands – as a case study, we also conduct a systematic literature review on the application of crop type maps in remote sensing science. Our analysis synthesizes 129 research articles through three core research questions: (1) What EO data are used with CDL; (2) What scientific problems and technologies are explored using CDL; and (3) What role does CDL play in remote sensing applications. Furthermore, we delve into the implications of our vision for new data products and propose emerging research topics, ranging from extending the spatiotemporal coverage of current data products to improving global mapping reliability and developing operational in-season crop mapping systems. This review paper not only serves as a reference for stakeholders seeking to utilize crop-specific land cover data in their work, but also outlines the directions for future geospatial data product development.