Reclamation of saline-sodic soil properties and improvement of rice (Oriza sativa L.) growth and yield using desulfurized gypsum in the west of Songnen Plain, northeast China

Several million hectares of salt-affected land in the western Songnen Plain, in northeast China, is characterized as hard saline-sodic soils because of their poor physical and chemical properties. Desulfurized gypsum, a by-product of thermal power plants for removal of sulfur from coal, may be used as an external source of Ca2 + for reclamation of saline-sodic soil in this plain because it is comparatively cheap, generally available, and has a high gypsum content (> 900 g kg− 1). In the present study, the effects of desulfurized gypsum on physical and chemical properties of saline-sodic soil and growth and yield of rice (Oriza sativa L.) were assessed in a soil column experiment. Desulfurized gypsum was added to the saline-sodic soil (ECe = 26.00 dS m− 1, SARe = 397.22 (mmolc L− 1)1/2, pH = 10.48) at rates of 0.00 g kg− 1 (control), 15.00 g kg− 1 (100% gypsum requirement (GR) treatment) and 30.00 g kg− 1 (200% GR treatment). The results demonstrated that desulfurized gypsum significantly increased the wet stability of macro-aggregates (> 0.25 mm), the IR and the Ks of the saline-sodic soil. Soil salinity (ECe), sodicity (SARe) and pH decreased to 2.72 ds m− 1, 8.65 (mmolc L− 1)1/2, and 8.05 in the 200% GR treatment, and 4.93 ds m− 1, 24.74 (mmolc L− 1)1/2 and 8.75 in the 100% GR treatment from 24.65 ds m− 1, 390.60 (mmolc L− 1)1/2 and 10.28 in the control, respectively. The yield of rice (O. sativa L.) increased from 0.0 g plant− 1 in control to 1.83 g plant− 1 and 2.45 g plant− 1 in 100% GR treatment and 200% GR treatment, respectively. Desulfurized gypsum is an effective amendment for saline-sodic soil in the west of Songnen Plain, northeast China.