A Novel Framework for Improving Soil Organic Carbon Mapping Accuracy by Mining Temporal Features of Time-Series Sentinel-1 Data

Zhibo Cui, Bifeng Hu, Songchao Chen, Nan Wang, Defang Luo () and Jie Peng
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Zhibo Cui: College of Agriculture, Tarim University, Alar 843300, China
Bifeng Hu: Department of Land Resource Management, Jiangxi University of Finance and Economics, Nanchang 330013, China
Songchao Chen: College of Environment and Resources Sciences, Zhejiang University, Hangzhou 310058, China
Nan Wang: Department of Earth System Science, Ministry of Education Key Laboratory for Earth System Modeling, Institute for Global Change Studies, Tsinghua University, Beijing 100084, China
Defang Luo: College of Agriculture, Tarim University, Alar 843300, China
Jie Peng: College of Agriculture, Tarim University, Alar 843300, China

Land, 2025, vol. 14, issue 4, 1-20

Abstract: Digital soil organic carbon (SOC) mapping is used for ecological protection and addressing global climate change. Sentinel-1 (S-1) microwave radar remote sensing data offer critical insights into SOC dynamics through tracking variations in soil moisture and vegetation characteristics. Despite extensive studies using S-1 data for SOC mapping, most focus on either single or multi-date periods without achieving satisfactory results. Few studies have investigated the potential of time-series S-1 data for high-accuracy SOC mapping. This study utilized S-1 data from 2017 to 2021 to analyze temporal variations in the correlation between SOC and time-series S-1 data in southern Xinjiang, China. The primary objective was to determine the optimal monitoring period for SOC. Within this period, optimal feature subsets were extracted using variable selection algorithms. The performance of the partial least squares regression, random forest, and convolutional neural network–long short-term memory (CNN-LSTM) models was evaluated using a 10-fold cross-validation approach. The findings revealed the following: (1) The correlation between time-series S-1 data and SOC exhibited both interannual and monthly variations, with the optimal monitoring period from July to October. The data volume was reduced by 73.27% relative to the initial time-series dataset when the optimal monitoring period was determined. (2) Introducing time-series S-1 data into SOC mapping significantly improved CNN-LSTM model performance (R 2 = 0.80, RPD = 2.24, RMSE = 1.11 g kg⁻ 1 ). Compared to models using single-date (R 2 = 0.23) and multi-date (R 2 = 0.33) data, the R 2 increased by 0.57 and 0.47, respectively. (3) The newly developed vertical–horizontal maximum and mean annual cumulative indices made a significant contribution (17.93%) to mapping SOC. Therefore, integrating the optimal monitoring period, feature selection, and deep learning model offers significant potential for enhancing the accuracy of digital SOC mapping.

Keywords: soil organic carbon; Sentinel-1; optimal monitoring period; convolutional neural network–long short-term memory (search for similar items in EconPapers)
JEL-codes: Q15 Q2 Q24 Q28 Q5 R14 R52 (search for similar items in EconPapers)
Date: 2025
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