Three-dimensional mapping of soil salinity in the southern coastal area of Laizhou Bay, China

Soil salinization is an important driver of land degradation and has been a major factor inhibiting agricultural production and development in the southern coastal area of Laizhou Bay. In this study, 3-D and 2-D geostatistics were respectively used to evaluate the spatial distribution of soil salinity and groundwater total dissolved solids (TDS) and depth. Results showed that soil electrical conductivity differed greatly within the same soil layer, and the difference in average electrical conductivity of different soil layers was relatively small. The mean value of TDS exceeded 3.0gL(-1) and the mean value of groundwater depth was 13.359m. The geographic distribution showed that the soil salinity gradually decreased from the north to the south horizontally, and the soil salinity showed a bottom accumulation tendency vertically. Over 90% of the study area has TDS values exceeding 1.0gL(-1), and approximately one-third of the area had a groundwater depth less than 3.0m. TDS and groundwater depth had good correlations with soil salinity, with coefficients of determination of 0.544 and 0.572, respectively. Changes in vegetation corresponded to changes in soil salinity. Soil salinity gradually decreased perpendicular to coastal lines in tidal flats without vegetative coverage to inland agricultural areas of wheat and vegetables. Soil salinization in the study area is mainly slight and moderate. Reasonable regional management measures are conducive to improving land economic benefits. The results provide a theoretical basis and reference for the partition, improvement, management of saline soil, and support for land degradation control.