Adding Straw and Gypsum to Improve Efficiency of Remediating Coastal Saline Soils

Abstract

【Objective】 Enhancing salt leaching is critical to improving the efficiency of desalinating salt-affected soils. In this paper, we investigated the efficacy of adding straw and gypsum to improve efficiency of remediation of coastal saline soil. 【Method】 The experiment was conducted using repacked soil columns 60 cm high with an internal diameter of 20 cm. The soil was mulched with straw and gypsum separately, or in their combination. The control was no amendment. The soils in the columns were saturated first and they were then leached by amount of water equivalent to five times the pore volume of the soil in the columns. During the experiment, we measured the electric conductivity (ECe), pH, and the concentration of sodium, potassium, calcium, and magnesium ions in the leachates. 【Result】 The saturated electrical conductivity and sodium adsorption ratio in the soils treated with gypsum and straw reached the requirement of ECe=4.0 dS/m after 5 pore volume of water passed through the columns. Efficacy of the amendment in improving salt leaching was ranked in the order of gypsum + straw >gypsum > straw=CK. 【Conclusion】 Amending the soil with gypsum alone or in combination with straw can improve salt leaching from the coastal saline soil, and improve its physical and chemical properties. Our results showed that adding straw alone did not show identifiable improvement.

Keywords

• saline soil
• straw
• gypsum
• leaching
• desalination