{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,3]],"date-time":"2026-04-03T13:17:20Z","timestamp":1775222240781,"version":"3.50.1"},"reference-count":43,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2021,5,4]],"date-time":"2021-05-04T00:00:00Z","timestamp":1620086400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002661","name":"Fonds De La Recherche Scientifique - FNRS","doi-asserted-by":"publisher","award":["40001781"],"award-info":[{"award-number":["40001781"]}],"id":[{"id":"10.13039\/501100002661","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Pilot studies have demonstrated the potential of remote sensing for soil organic carbon (SOC) mapping in exposed croplands. However, the use of remote sensing for SOC prediction is often hindered by disturbing factors at the soil surface, such as photosynthetic active and non-photosynthetic active vegetation, variation in soil moisture or surface roughness. With the increasing amount of freely available satellite data, recent studies have focused on stabilizing the soil reflectance by building image composites. These composites tend to minimize the disturbing effects by applying sets of criteria. Here, we aim to develop a robust method that allows selecting Sentinel-2 (S-2) pixels with minimal influence of the following disturbing factors: crop residues, surface roughness and soil moisture. We selected all S-2 cloud-free images covering the Belgian Loam Belt from January 2019 to December 2020 (in total 36 images). We then built nine exposed soil composites based on four sets of criteria: (1) lowest Normalized Burn Ratio (NBR2), (2) Normalized Difference Vegetation Index (NDVI) &lt; 0.25, (3\u20135) NDVI &lt; 0.25 and NBR2 &lt; threshold, (6) the \u2018greening-up\u2019 period of a crop and (7\u20139) the \u2018greening-up\u2019 period of a crop and NBR2 &lt; threshold. The \u2018greening-up\u2019 period was selected based on the NDVI timeline, where \u2018greening-up\u2019 is considered as the last date of acquisition where the soil is exposed (NDVI &lt; 0.25) before the crop develops (NDVI &gt; 0.25). We then built a partial least square regression (PLSR) model with 10-fold cross-validation to estimate the SOC content based on 137 georeferenced calibration samples on the nine composites. We obtained non-satisfactory results (R2 &lt; 0.30, RMSE &gt; 2.50 g C kg\u20131, and RPD &lt; 1.4, n &gt; 68) for all composites except for the composite in the \u2018greening-up\u2019 stage with a NBR2 &lt; 0.07 (R2 = 0.54 \u00b1 0.12, RPD = 1.68 \u00b1 0.45 and RMSE = 2.09 \u00b1 0.39 g C kg\u20131, n = 49). Hence, the \u2018greening-up\u2019 method combined with a strict NBR2 threshold allows selecting the purest exposed soil pixels suitable for SOC prediction. The limit of this method might be its coverage of the total cropland area, which in a two-year period reached 62%, compared to 95% coverage if only the NDVI threshold is applied.<\/jats:p>","DOI":"10.3390\/rs13091791","type":"journal-article","created":{"date-parts":[[2021,5,5]],"date-time":"2021-05-05T22:51:42Z","timestamp":1620255102000},"page":"1791","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":59,"title":["Sentinel-2 Exposed Soil Composite for Soil Organic Carbon Prediction"],"prefix":"10.3390","volume":"13","author":[{"given":"Klara","family":"Dvorakova","sequence":"first","affiliation":[{"name":"Georges Lema\u00eetre Centre for Earth and Climate Research, Earth and Life Institute, Universit\u00e9 Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3865-1912","authenticated-orcid":false,"given":"Uta","family":"Heiden","sequence":"additional","affiliation":[{"name":"German Aerospace Center (DLR), Remote Sensing Technology Institute (IMF), Oberpfaffenhofen, 82234 Wessling, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4007-0241","authenticated-orcid":false,"given":"Bas","family":"van Wesemael","sequence":"additional","affiliation":[{"name":"Georges Lema\u00eetre Centre for Earth and Climate Research, Earth and Life Institute, Universit\u00e9 Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium"}]}],"member":"1968","published-online":{"date-parts":[[2021,5,4]]},"reference":[{"key":"ref_1","unstructured":"United Nations (2021, March 14). 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