The effect of phosphogypsum and steel pickling electrolyte on chemical characteristics of paddy soils in the conditions of the Rostov region

Abstract

Purpose: to study the effect of various ameliorants and their combinations, as well as leaching on paddy soil characteristics in laboratory conditions for determining the possibility of their further application. Materials and methods. In the course of the research, a soil reclamation survey of paddy fields in Rostov region was carried out. Soil samples analyzes were carried out in an environmental analytical laboratory using generally accepted methods. Soils with different chemistry, degrees of salinity and salinization, and different gypsum content were taken for the laboratory experiment. Based on the results of soil samples study, phosphogypsum, steel pickling electrolyte, and their combinations were used as ameliorants. Results. Leaching without ameliorants contributed to a total salt content decrease. On slightly saline soils of chloride-sulfate chemistry, their number decreased by 54 %, and on moderately saline soils of sulfate salinity by only 5 %. Ameliorants, especially phosphogypsum, increased their amount in non-saline soils by 5 times, and in slightly saline soils – by 2.7 times due to the accumulation of calcium sulfates. Their accumulation was not observed in moderately saline gypsum-containing soils. The steel pickling electrolyte reduced their quantity by 18 %, compared to the control. The soil absorption complex of non-saline and slightly saline soils was optimized, but in gypsum-containing soils it remained virtually unchanged. Conclusions. Laboratory experiments have shown that soils of chloride-sulfate salinity, having magnesium salinity and undersaturation with exchangeable calcium in the soil absorption complex, can be improved by using phosphogypsum and steel pickling electrolyte as an ameliorant, as they are the most accessible to land users. They promote the formation of gypsum, which accelerates the process of replacing exchangeable magnesium and sodium with calcium. Reclamation of highly gypsum-rich soils with a gypsum content of more than 20 % and easily soluble salts of more than 1.0 % using traditional methods is not very successful.

Keywords

• chemical soil characteristics
• chemical reclamation
• gypsum-containing soils
• salinity chemistry
• salt composition of soil