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), SAR(e) = 397.22 (mmol(c) 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 K-s of the saline-sodic soil. Soil salinity (ECe), sodicity (SAR(e)) and pH decreased to 2.72 ds m(-1), 8.65 (mmol(c) L-1)(1/2), and 8.05 in the 200% GR treatment, and 4.93 ds m(-1), 24.74 (mmol(c) L-1)(1/2) and 8.75 in the 100% GR treatment from 24.65 ds m(-1), 390.60 (mmol(c) 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. (C) 2012 Elsevier B.V. All rights reserved.