Interaction Features of Some Acid Ameliorants in the Process of Chemical Reclamation of Sodic Solonetz-Solonchaks

The purpose of the study is to reveal the mechanisms of interaction of some acid ameliorants in the process of chemical reclamation of Sodic Solonetzes-Solonchaks (SSS). The experiments have been carried out within 2018-2020 under laboratory conditions using soil column techniques. 13 soil samples have been collected from Ararat valley, Republic of Armenia. These soils have a high alkaline reaction (pH 9.5-10.5), a sodium exchangeable percentage (ESP 44.5-74.0%) and electrical conductivity (EC 12.4-42.2 dS cm-1). It has been shown, that in the case of iron sulphate application the products of its hydrolysis promote soil dealkalization and improvement of soil physical properties due to creation of iron-clay complexes accumulated in the soil primarily in crystalline form (66-67 %). It has been revealed, that the penetration depth of 1% of sulphuric acid and iron sulphate solutions during the chemical reclamation is 8-12 cm, and the accumulation of gypsum in topsoil (0-12 cm) is observed. Due to the higher solubility of magnesium sulphate in the process of acidification, soil dealkalization and the increase of filtration rate of soil solutions (10-12 cm day-1) are watched. During the soil leaching process, the newly-formed gypsum plays a major role in further dealkalization process of soils and regulation of exchangeable Ca and Mg relation in optimal range. It is shown, that in the process of acidification, the pressure of the formed carbon dioxide gas (CDG) in the soil may reach up to 2.2 atm, in which the solubility of calcium and magnesium carbonate are increased, and the share of CDG in soil dealkalization process is in average 50%. The results obtained allow for the opportunity to recommend improvements of SSS chemical reclamation technology.