2C-Net: A Novel Spatiotemporal Dual-Channel Network for Soil Organic Matter Prediction Using Multi-Temporal Remote Sensing and Environmental Covariates

Abstract

Highlights: What are the main findings? Propose a new framework for soil organic matter (SOM) mapping by combining deep learning. Considering multi-temporal remote sensing images (MTRSI) as multi-channel time series data to assist in SOM mapping. What is the implication of the main finding? The accuracy of SOM prediction using this framework surpasses the widely used Random Forest (RF) method. The bare soil period after tilling is a more important time window for SOM inversion. Soil organic matter (SOM) is essential for ecosystem health and agricultural productivity. Accurate prediction of SOM content is critical for modern agricultural management and sustainable soil use. Existing digital soil mapping (DSM) models, when processing temporal data, primarily focus on modeling the changes in input data across successive time steps. However, they do not adequately model the relationships among different input variables, which hinders the capture of complex data patterns and limits the accuracy of predictions. To address this problem, this paper proposes a novel deep learning model, 2-Channel Network (2C-Net), leveraging sequential multi-temporal remote sensing images to improve SOM prediction. The network separates input data into temporal and spatial data, processing them through independent temporal and spatial channels. Temporal data includes multi-temporal Sentinel-2 spectral reflectance, while spatial data consists of environmental covariates including climate and topography. The Multi-sequence Feature Fusion Module (MFFM) is proposed to globally model spectral data across multiple bands and time steps, and the Diverse Convolutional Architecture (DCA) extracts spatial features from environmental data. Experimental results show that 2C-Net outperforms the baseline model (CNN-LSTM) and mainstream machine learning model for DSM, with R2 = 0.524, RMSE = 0.884 (%), MAE = 0.581 (%), and MSE = 0.781 (%)2. Furthermore, this study demonstrates the significant importance of sequential spectral data for the inversion of SOM content and concludes the following: for the SOM inversion task, the bare soil period after tilling is a more important time window than other bare soil periods. 2C-Net model effectively captures spatiotemporal features, offering high-accuracy SOM predictions and supporting future DSM and soil management.