A laboratory study of the effects of water dissolved gypsum application on hydraulic conductivity of saline-sodic soil under intermittent ponding conditions

Reclamation of saline-sodic soils has great importance in agricultural management. The objective of this study was to evaluate the effectiveness of the methods used to apply water and gypsum on hydraulic conductivity of a saline-sodic soil with an electrical conductivity of 28 dS/m and exchangeable sodium percentage of 46%. The experiment was conducted under laboratory conditions using disturbed and non-cropped soil columns. A total of 45 cm of water was applied to each column with 3, 6, or 9 separate water applications. Finely ground gypsum (< 0.5 mm maximum particle diameter) was either incorporated into the surface 2 to 3 cm of soil or was dissolved into the leaching water at a rate corresponding to 3.82 t/ha. Six or nine separate water applications of gypsum dissolved into leaching water significantly increased hydraulic conductivity (P < 0.01). Soil hydraulic conductivity increased (P < 0.01) with depth at separate applications of gypsum.