添加秸秆和石膏改善滨海盐渍土盐分淋洗效果的试验研究

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

【目的】探讨添加石膏和秸秆对滨海滩涂盐渍土盐分淋洗效果的改善作用。【方法】采用直径为20 cm,土层深度为60 cm的土柱开展室内试验,设置了对照组、秸秆覆盖、石膏覆盖以及秸秆+石膏覆盖4种试验处理;土柱饱和后观测了时长为5个淋洗周期(PV)的排水质量浓度变化,每2 L排水取淋洗液测量电导率、pH值和钠钾钙镁离子质量浓度;比较了土壤盐分淋洗过程中及试验结束后土壤EC_(e)和SAR值变化。【结果】①石膏覆盖处理和秸秆覆盖处理的土壤饱和电导率及交换性钠百分率在淋洗了5个淋洗周期后均达到脱盐标准(EC_(e)=4.0 dS/m)。②土壤盐分淋洗效果递减次序为秸秆+石膏覆盖>石膏覆盖>秸秆覆盖=对照组。【结论】在滨海滩涂盐渍土壤改良过程中,单独添加石膏覆盖或添加秸秆+石膏覆盖均可改善土壤的理化性质;秸秆+石膏覆盖处理对盐分淋洗有促进作用,单独使用则无明显效果。

【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(EC_(e)),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 EC_(e)=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.