Spatial Variation Characteristics of Soil Salinity and Nutrient After Reclamation of Abandoned Coastal Salt Pans

<p indent="0mm"> Coastal saline soil is an important cultivated land reserve resource in China, which is of great significance to national food security and expanding cultivated land resources. In this study, we used the combination of classical statistics and geostatistics to study the change trend and spatial distribution characteristics of soil salinity and nutrients under different reclamation years. The results showed that the mean salt content of soil was <sc>1.16 g/kg</sc> in reclamation area 1, which was at mild salinization level, and the mean salt content was <sc>2.70 g/kg</sc> in reclamation area 2, which was at moderate salinization level. The content of organic matter, ammonium nitrogen, available phosphorus and cation exchange capacity were basically the same in the two study areas, while the difference of nitrate nitrogen content was large, with a difference of nearly three times. The coefficient of variation of each index ranged from 19.73% to 97.53%, which belongs to the moderate variation intensity. All the soil property indexes have strong spatial correlation in the reclamation area 1. The soil salt content and nitrate nitrogen have strong spatial correlation in the reclamation area 2, and the nugget to sill of other indexes was between 25% and 75%, with moderate spatial correlation. The two study areas showed significant negative relationships between soil salinity and available nitrogen, available phosphorus, cation exchange capacity. Available nitrogen showed a significant positive relationship with available phosphorus and cation exchange capacity. Available potassium showed a significant positive relationship with available phosphorus. The semi-variance model of each property index in the two study areas conforms to spherical model and Gaussian model. The spatial distribution of soil attribute indexes in the two study areas was significantly different. The interpolation results showed that the spatial distribution of soil attributes was different between the two study areas, and the spatial distribution characteristics of available potassium, available phosphorus and cation exchange capacity were similar in reclamation area 1. The spatial distribution characteristics of available nitrogen, available potassium, available phosphorus and cation exchange capacity were similar in reclamation area 2. The results provide technical support for the improvement and utilization, disaster prevention and mitigation, and policy formulation of saline soil in coastal areas.