Journal Article

Estimation of Soil Salt Content at Different Depths Using UAV Multi-Spectral Remote Sensing Combined with Machine Learning Algorithms

Cui, Jiawei, Cui, Xin, Li, Guang, Han, Wenting, Ma, Weitong, Chen, Xiangwei

2023

Overview

Soil salinization seriously affects the sustainable development of agricultural production; thus, the timely, efficient, and accurate estimation of soil salt content (SSC) has important research significance. In this study, the feasibility of soil salt content retrieval using machine learning models was explored based on a UAV (unmanned aerial vehicle) multi-spectral remote sensing platform. First, two variable screening methods (Pearson correlation analysis and Grey relational analysis) are used to screen the characteristic importance of 20 commonly used spectral indices. Then, the sensitive spectral variables were divided into a vegetation index group, a salt index group, and a combination variable group, which represent the model. To estimate SSC information for soil depths of 0–20 cm and 20–40 cm, three machine learning regression models were constructed: Support Vector Machine (SVM), Random Forest (RF), and Backpropagation Neural Network (BPNN). Finally, the salt distribution map for a 0–20 cm soil depth was drawn based on the best estimation model. The results of experiments show that GRA is better than PCA in improving the accuracy of the estimation model, and the combination variable group containing soil moisture information performs best. The three machine learning models have achieved good prediction effects to some extent. The accuracy and stability of the model are considered comprehensively, the prediction effect of 0–20 cm is higher than that of 20–40 cm, and the validation set coefficient of determination (R2), Root-Mean-Square-Error (RMSE), and Mean Absolute Error (MAE) of the best inversion model are 0.775, 0.055, and 0.038, and the soil salt spatial map based on the optimal estimation model can reflect the salinization distribution in the study area. Therefore, this study shows that a UAV multi-spectral remote sensing platform combined with machine learning models can better monitor farmland soil salt content.

• Publisher: MDPI AG
• Subject: Accuracy / Agricultural development / Agricultural land / Agricultural production / agricultural soils / Algorithms / Aluminum / Artificial intelligence / Artificial neural networks / Back propagation networks / Comparative analysis / Correlation analysis / Data collection / Distribution / Drone aircraft / Efficiency / Feasibility studies / Learning algorithms / Machine learning / Measurement / Methods / multi-spectral remote sensing / Multispectral photography / Neural networks / Precipitation / prediction / Regression analysis / Regression models / Remote sensing / Root-mean-square errors / Salinization / Salt / salt content / salt distribution map / Salts / Soil depth / Soil moisture / Soil salinity / soil salinization / soil salt content / soil salts / soil water / Soils, Salts in / Support vector machines / Sustainable development / unmanned aerial vehicle (UAV) / Unmanned aerial vehicles / variable screening / Variables / Vegetation index