脱硫石膏施用下宁夏盐化碱土水盐运移特征

Characteristics of Soil Water and Salt Movement in a Saline Alkali Soil Treated with Desulfurized Gypsum

为定量描述脱硫石膏施用下盐化碱土土壤剖面盐分与淋洗水量的关系,通过室内土柱淋洗试验开展了脱硫石膏施用下不同淋洗水量对宁夏盐化碱土水盐运移影响的研究。结果表明:施用脱硫石膏对增加水分入渗和降低0—20cm土层土壤pH、盐分含量产生了积极影响,土壤脱盐率84.39%~95.41%,但较大水量的淋洗有可能会加剧土壤碱化。连续淋洗条件下,最大脱盐深度位于60—80cm土层。脱硫石膏施用下,0—20cm土层Cl^-、Na^+溶脱率随淋洗水量的增加变化不大,低淋洗水量下,SO_4^(2-)溶脱率低于Na^+和Cl^-,高淋洗水量下,3种离子溶脱率接近;20—40cm土层主要盐分离子溶脱率由大到小依次为Cl^-、SO_4^(2-)、Na^+,各离子脱盐率随淋洗水量的增加先增加较快后趋于平缓。当淋洗水量达到60cm时,SO_4^(2-)和Na^+在80—100cm土层累积,Cl^-则运移至100cm土层以下。

In order to describe the quantitative relationship between soil salinity in the profile of a saline alkali soil and leaching water volume,the effects of leaching water volume on soil water and salt movement in a typical saline alkali soil in Ningxia Province treated with desulfurized gypsum were studied by an indoor soil column leaching test.The results showed that applying desulfurized gypsum had a positive effect on increasing water infiltration,reducing soil pH and salinity of the 0-20 cm soil layer,and soil desalinization rate was between 84.39%and 95.41%,but large leaching water volume might aggravate soil alkalization.Under continuous leaching condition,the maximum desalting depth lied in the 60-80 cm soil layer.In the 0-20 cm soil layer,the desalting ratio of Cl^-and Na^＋had a small variation with the increasing amount of leaching water volume.Under small leaching water volume,the desalting ratio of SO4^2-was lower than those of Cl^-and Na^＋.Under large leaching water volume,the desalting ratios of three ions were very close.In the 20-40 cm soil layer,the desalting ratio of major salt ion was in a descending order of Cl^- 〉SO4^2- 〉Na^＋,and they increased fast first and then became gentle with increasing leaching water volume,and under small leaching water volume,Cl^-,Na^＋,SO4^2-accumulated in the 40-60 cm soil layer.Under large leaching water volume,they continued downward migration.When leaching watervolume reached 60 cm,SO4^2-and Na^＋accumulated in the 80-100 cm soil layer,while Cl^-migrated to〉100cm soil layer.