Effect of Brackish Ice on Salt and Nutrient Contents of Saline Soil in Flue-Gas Desulfurization Gypsum Amended, Raised Bed Agroecosystem

摘要

The effect of brackish ice application on the salt content and nutrient levels of a saline soil was determined in a flue-gas desulfurization (FGD) gypsum amended, raised bed agroecosystem. Experimental plots in the raised bed were exposed to six treatments: 0, 4000, and 8000 m(3) ha(-1) brackish ice mulch, with or without the use of FGD gypsum. The applied brackish ice significantly decreased (P < 0.05) the electrical conductivity of a saturated soil paste extract (ECe) to 4.22 (4000 m(3) ha(-1)) and 3.85 dS m(-1) (8000 m(3) ha(-1)) from 7.20 dS m(-1) (non-brackish ice mulch) in the 0- to 20-cm soil layers in the absence of FGD gypsum. Electrical conductivity was also significantly decreased in the 0- to 40-cm soil layers following incorporation of FGD gypsum. The application of brackish ice significantly reduced (P < 0.05) soil Na adsorption ratio (SAR) to < 11 and exchangeable Na percentage (ESP) in the 0- to 20-cm soil layer, compared with the control treatment to which brackish ice had not been applied, regardless of FGD gypsum incorporation. The incorporation of FGD gypsum increased soil ECe to 12.89, 7.72, and 7.03 dS m(-1) (P < 0.01) but gave a lower soil SAR (P < 0.05) in the 0- to 20-cm soil layer following zero, low, and high volumes of brackish ice application compared with the same treatments without FGD gypsum. The incorporation of FGD gypsum significantly decreased soil pH in the 0- to 20-cm soil layer compared with the treatment without FGD gypsum, regardless of brackish ice volume. The application of brackish ice significantly decreased the available P of the 0- to 20-cm soil layer (P < 0.05) and NO3-N content of the 0- to 40-cm soil layer (P < 0.05) compared with the control treatment without brackish ice when FGD gypsum was not incorporated. These results indicated that mulching of raised beds of saline soil by brackish ice seems to be a promising technology for growing spring crops on soils that would normally be unproductive.