It is provision of drainage and leaching of soluble salts from the soil what is needed in saline soils amelioration.

Saline soils contains more amount of neutral salts (Chlorides and sulphates of Ca, Mg, Na and K) as compare to carbonates and bicarbonates of Na. To manage the saline soils there is no need of any chemical amendment as they are neutral soluble salts. Here we can manage the soils by Leaching process (Removal of salts below the root zone by using good quality water)

Salt-affected soils can be corrected by: improving drainage, leaching, reducing evaporation, applying chemical treatments, and a combination of these methods. Gypsum is the most common chemical amendment used to correct saline-sodic or sodic soils that have no calcium source such as gypsum or free carbonates.

If your soil contains free carbonates, you can add acids to it to form gypsum, which will react with the soil to remove the exchangeable sodium. Add sulfuric acid, sulfur, iron sulfates and aluminum sulfate, which will react in the soil to produce acid. The acid will then react with the calcium carbonates (limestone) to form calcium sulfate (gypsum), water and carbon dioxide. The acidity may also displace some of the sodium.

https://agrilifeextension.tamu.edu/library/gardening/managing-soil-salinity/

In the evaluation of chemical actions to correct salinity, it is inferred that Calcium is essential to combat the effects of salinity on the physicochemical properties of the soil and the exclusion of the salts that cause the problem, such as sodium salts, in addition , high level of Calcium is positive, it is an indicator of minimum concentrations of other exchangeable cations that cause negative effects, such as Sodium Na+ in sodic soils. The rehabilitation of sodic soils is achieved by replacing most of the Na+ with Ca+2. Likewise, in terms of acidity/alkalinity, in naturally acidic soils or soils acidified by agricultural use (loss of exchange bases due to the export of crop nutrients, high application doses of ammoniacal or ammonium-forming fertilizers, etc.) Calcium and magnesium-calcium correctors are used, such as calcite and dolomite, with an alkaline reaction in the soil, and which are also effective in providing Ca and Mg to crops. Calcium sulfate hemihydrate (Ca(SO4)1/2H2O) has been applied in many studies in the recovery of saline soils due to its low cost.

Ponding of water lead to solubilization of salts (sulphate & chloride of Na, Ca etc) following by their drainage is basically a chemical method of amelioration of saline soil. Because, here water is a chemical and solubilization is a chemical process.

To minimize the salinity of agricultural land, high levels of calcium, dihydrated calcium sulfate Ca(SO4)1/2H2O) (baked gypsum) are used, in addition, with irrigation, with fertilizers and biological components.