Abstract: In order to study the improvement effect of different amendments on coastal soil, a pot experiment was conducted to study the effects of calcium sulfate, aluminium sulfate, ferric sulfate, ferrous sulfate and sulfur on soil total salt, pH and ion composition. The results showed that with the different amendments applied, the content of ions in the infiltration water varied greatly. In the first leaching, the contents of Na⁺ and Cl^- in the infiltration water treated with calcium sulfate, aluminum sulfate and ferric sulfate were 54.78% and 58.25%, 35.44% and 39.22%, 32.65% and 34.82% higher than those of CK, respectively, indicating that the addition of these three amendments had a better effect on soil salinity reduction, and calcium sulfate treatment had the best effect. In the second leaching, the Na⁺ content of ferric sulfate, calcium sulfate and aluminum sulfate treatment was 75.14%~347.76% higher than that of CK. Combined with two times of leaching, the results showed that calcium sulfate treatment had a more significant effect on the leaching of Na⁺ in soil. Compared with CK, the soil pH of each amendment treatment decreased to varying degrees, and the pH decreased by 2.23%~3.84%. Different amendments had different effects on soil ions. The contents of Ca²⁺ and Mg²⁺ in soil treated with amendments were higher than those of CK. Considering the effects of different amendments on soil pH, Na⁺ and Cl^-, it was suggested that ferric sulfate and calcium sulfate should be combined to improve coastal saline-alkali land.

Key words: soil, coastal saline-alkali soil, amendment, soluble salt, salt ions