河套平原弃耕地土壤盐碱化特征

运用经典统计和主成分分析方法,对河套平原弃耕地盐渍化土壤全盐量、pH、阴阳离子组成、碱化度(ESP)的分布特征进行了分析。结果表明:研究区土壤为中度至重度盐渍化,土壤全盐、pH、碱化度(ESP)在剖面中的变化趋势一致,呈表聚和底聚两个过程。全盐量介于2.80~6.69g kg-1之间,pH介于9.20~9.69之间,碱化度介于10.97%~33.33%之间。0~60 cm土层全盐量随土层深度增加而降低,60~120 cm土层全盐量随土层深度增加而增加。剖面中阳离子以Na++K+为主;阴离子以SO42-为主。除pH外,土壤各盐碱指标呈强烈空间变异特征;不同土层SO42-与Ca2+、Mg2+、全盐量差异达极显著水平,Cl-与K++Na+相关性随土层深度增加而减弱,pH、碱化度与CO32-达极显著水平。土壤全盐量、SO42-可作为研究区土壤盐化状况特征因子;CO32-、HCO3-、pH可作为研究区土壤碱化状况特征因子。由此可见,在改良利用过程中要以降低土壤盐度和碱度来调控离子组成,进而改善土壤结构。

Characteristics of Salinization of Deserted Farmland in Hetao Plain, China

AbstractObjective]To explore characteristics of the salinization of deserted farmlands in the Hetao Plain.Method]In this study soil samples were collected from the farmlands and analyzed with the classical statistics and principal component analysis methods for total salt content,pH,anion and cation composition,and distribution of alkalization degree.Result]Results show that the abandoned farmlands in the Hetao plain were mild to severe in salinization,with soil salt content,pH and alkalization degree varying between 2.80 and 6.69 g kg-1,9.20 and 9.69,and 10.97% and 33.33%,respectively and distributed similarly along the soil profile,that is,accumulating in the surface and bottom. The salt content decreased with soil depth in the 0~60 cm soil layer,increased with soil depth in the 60~120 cm soil layer. The cations in the soil profile were dominated with Na+ and K+ while the anions were with SO42-. All the salinization indices,except soil pH,showed extremely strong spatial variability. Contents of SO42-,Ca2+,Mg2+ and total salt varied sharply from soil layer to soil layer.The correlations of Cl- with K+ and Na+ declined in significance with soil depth. Soil pH and alkalization degree were significantly correlated with the content of CO32-. Principal component analysis shows that the total salt and SO42- could be used as diagnostic factors of soil salinization;while CO32-,HCO3- and pH as diagnostic factors of soil alkalization in this research area,explaining 88.74% of the total variance.Conclusion]Therefore,it is quite obvious that the deserted farmlands in the Hetao Plain are severe in salinization degree,and it is essential to lower soil salinity or alkalinity,regulate soil ion composition and improve soil structure during the soil amelioration process. It is expected that this study may provide certain theoretical basis for ameliorating and utilizing salinized soil,and improving regional ecological environment of deserted farmlands in the Hetao Plain.