Soil Salt Content and Its Relationship with Crops and Groundwater Depth in the Yinchuan Plain (China) Using Remote Sensing

Soil salt content and its relationships with crops and water table depth were investigated in this study by using remote sensing techniques and field measurements in the Yinchuan plain of China. Moderate Resolution Imaging Spectroradiometer-Normalized Difference Vegetation Index (MODIS NDVI) was used as an indicator of crop development, field samples were analyzed for soil salt content, and observation wells provided water table data. Comparison of crop development defined from NDVI to soil salt values indicated that crop may develop well when the surface soil salt content is lower than 0.5 g/kg. Its growth is restricted when the soil salt content is between 0.5 and 4 g/kg, and little crop growth occurs when the soil salt content is greater than 4 g/kg. Comparison of soil salinity and water table depth in the beginning of the growing season showed, that areas with water table depth between 0.9 m and 3 m are the most affected by soil salinization. This information is crucial for the optimal control of drainage and irrigation in this important cropping region of China.