不同潜水埋深下土壤水盐运移特征及其交互效应

Migration characteristics of soil water and salt and their interaction under different groundwater levels

为探讨盐水矿化度下土壤水盐分布特征对潜水埋深的响应规律及其水盐交互效应,以黄河三角洲建群种柽柳（Tamarix chinensis Lour）栽植的土壤柱体为研究对象,模拟设置0.3、0.6、0.9、1.2、1.5和1.8 m共6种潜水水位,测定分析各水位处理下不同土壤剖面的相对含水率、含盐量及土壤溶液绝对浓度等水盐参数。结果表明：随潜水水位的增加,整个土柱水分均值显著降低,土壤含盐量和溶液绝对浓度均值先升高后降低,1.2 m水位是土壤水盐变化的转折点,此水位下各土壤剖面的含盐量和土壤溶液绝对浓度均达最高。土柱水分和盐分变化幅度最大的水位分别在中水位0.9∽1.2 m,浅水位0.6 m,土壤溶液绝对浓度变化最剧烈的是深水位1.5∽1.8 m。随土壤深度的增加,土壤水分显著升高,土壤盐分先降低后升高,表土层盐分均值最高达1.36%,但土壤溶液绝对浓度显著减小。土壤含盐量、土壤相对含水率与潜水水位分别呈极显著（P〈0.01）和显著（P〈0.05）负相关,土壤相对含水率与盐分呈极显著正相关（P〈0.01）。地下盐水矿化度下,柽柳幼苗栽植深度应超过20 cm深,适宜潜水水位在1.5∽1.8 m,栽植深度以30∽40 cm较好。研究结果可为地下盐水作用条件下土壤次生盐渍化的防治和柽柳栽植管理提供参考。

Soil salt and water closely related to groundwater depth mainly affect vegetation distribution pattern and community succession of the Yellow River Delta. Thus,it is important to explain the changing process of water and salt in groundwater and soil and their effects on the occurrence of the secondary salinization. This study aimed to understand the response of soil water-salt distribution characteristics to groundwater depth and their interactive effects under saline groundwater conditions. To achieve the objective, a laboratory experiment was carried out in a controllable greenhouse of Shangdong Provincial Key Laboratory of Eco-Environmental Science for Yellow River Delta, Binzhou University, China in 2014. Soils were collected from Yellow River downstream and air-dried. A total of 18 soil columns planted with Tamarix chinensis Lour, a constructive species in the Yellow River Delta were prepared and the soil columns were made of polyvinyl chloride resin. These soil columns were immersed into saline water that simulated groundwater levels of 0.3, 0.6, 0.9, 1.2, 1.5 and 1.8 m. The water-salt parameters（such as relative soil water content, soil salt content and soil solute absolute concentration） of different soil column profiles were measured. The results showed that： 1） Relative soil water content of soil columns was greatly decreased as the level of groundwater increased while soil salt content： soil moisture fluctuated dramatically for treatment of groundwater level 0.9-1.2 m and was stable for groundwater level 0.3-0.6 m; 2） Soil solution absolution concentration increased first and then decreased, and the turning point of soil water and salt content occurred at level of groundwater 1.2 m, under which soil salinity and soil solution absolute concentration of soil profiles were both the highest; 3） The maximum variation of water content, salt content and soil solution absolution concentration occurred for treatments of the level of groundwater 0.9-1.2 m, 0.6 m and 1.5-1.8 m, respectively; 4） As soil depth increased, the relative soil water content also increased, the soil salt content fell first and then rose up to 1.34% at surface layer, while soil solution absolute concentration decreased; From the soil surface down the soil profile, the change range and degree of relative soil water content and soil solution absolute concentration decreased gradually with increasing groundwater level; The groundwater level corresponding to the highest salt content of all soil profiles was 1.2 m; and 5） Soil salt content and relative soil water content had significant negative correlations with level of groundwater at P0.01 and P0.05, respectively, and a significant positive correlation（P0.01） was observed between relative soil water content and soil salt content. Based on changes in soil moisture, salinity and soil solution absolute concentration, the T. chinensis should be planted 20 cm at least of soils, preferably 30-40 cm under saline groundwater conditions. The suitable level of groundwater was between 1.5 and 1.8 m. The results can provide important information for the prevention of soil secondary salinization, and the planting and management of T. chinensis under saline groundwater conditions.