Desiccation cracking during water evaporation is a common phenomenon in soda saline-alkali soils and is mainly determined by soil salinity. Therefore, quantitative measurement of the surface cracking status of soda saline-alkali soils is highly significant in different applications. Texture features can help to determine the mechanical properties of soda saline-alkali soils, thus improving the understanding of the mechanism of desiccation cracking in saline-alkali soils. This study aims to provide a new standard describing the surface cracking conditions of soda saline-alkali soil on the basis of gray-level co-occurrence matrix (GLCM) texture analysis and to quantitatively study the responses of GLCM texture features to soil salinity. To achieve this, images of 200 field soil samples with different surface cracks were processed and calculated for GLCMs under different parameters, including directions, gray levels, and step sizes. Subsequently, correlation analysis was then conducted between texture features and electrical conductivity (EC) values. The results indicated that direction had little effect on the GLCM texture features, and that four selected texture features, contrast (CON), angular second moment (ASM), entropy (ENT), and homogeneity (HOM), were the most correlated with EC under a gray level of 2 and step size of 1 pixel. The results also showed that logarithmic models can be used to accurately describe the relationships between EC values and GLCM texture features of soda saline-alkali soils in the Songnen Plain of China, with calibration R2 ranging from 0.88 to 0.92, and RMSE from 2.12 × 10-4 to 9.68 × 10-3, respectively. This study can therefore enhance the understanding of desiccation cracking of salt-affected soil to a certain extent and can also help to improve the detection accuracy of soil salinity.
Keywords: GLCM; Songnen Plain; soda saline–alkali soil; soil surface crack; texture feature.