Assessment of Semi-Automated Techniques for Crop Mapping in Chile Based on Global Land Cover Satellite Data

In recent years, the Chilean agricultural sector has undergone significant changes, but there is a lack of data that can be used to accurately identify these transformations. A study was conducted to assess the effectiveness of different spatial resolutions used by global land cover products (MODIS, ESA and Dynamic World (DW)), in addition to the demi-automated methods applied to them, for the identification of agricultural areas, using the publicly available agricultural survey for 2021. It was found that lower-spatial-resolution collections consistently underestimated crop areas, while collections with higher spatial resolutions overestimated them. The low-spatial-resolution collection, MODIS, underestimated cropland by 46% in 2021, while moderate-resolution collections, such as ESA and DW, overestimated cropland by 39.1% and 93.8%, respectively. Overall, edge-pixel-filtering and a machine learning semi-automated reclassification methodology improved the accuracy of the original global collections, with differences of only 11% when using the DW collection. While there are limitations in certain regions, the use of global land cover collections and filtering methods as training samples can be valuable in areas where high-resolution data are lacking. Future research should focus on validating and adapting these approaches to ensure their effectiveness in sustainable agriculture and ecosystem conservation on a global scale.