Comparison of Gypsum, Sulfuric Acid, and Sulfurous Acid for the Reclamation of Salt-Affected Soils.

One of the most important agricultural challenges affecting the world is soil salinization and soil sodicity.  Irrigation with poor quality water and the lack of adequate drainage can lead to salinization and the accumulation of sodium in soils.  The management of salt-affected soils usually requires the addition of amendments that aid in the displacement of sodium and improve soil permeability by reducing clay swelling and dispersion. Gypsum is a common amendment used to reclaim salt-affected soils but can be expense.  Another common amendment, sulfuric acid, is hazardous to handle and corrosive to irrigation systems. As an alternative, sulfur burners are now being used by some growers because elemental sulfur is non-hazardous to handle, less corrosive, cheaper and has recently been approved by the USDA National Organic Program.  Sulfur burners generate SO₂ gas which readily dissolves in water to form sulfurous acid, a weak acid. The benefit of using a weak acid may be better distribution of the amendment throughout the soil profile and as a result, improved reclamation.  Thus, we propose that sulfurous acid may be a better amendment for sodic soil reclamation than either sulfuric acid or gypsum.  In this project we conducted a laboratory study to evaluate the relative benefits of gypsum, sulfuric acid, and sulfurous acid to remove sodium and improve soil permeability.