吉林西部退化草原土壤盐渍化特征分析

Soil salinity, sodicity and alkalinity characteristics of degraded grassland in the west of Jinlin province, China

对吉林西部退化草原六种常见植被类型下的土壤(0～20 cm)盐渍化特征进行了分析。采用国际上通用的土壤饱和浸提液电导率(ECe)、碱化度(ESP)和pH分别表征土壤的盐度、钠质化和酸碱程度。土壤盐度分为轻度、中度、重度和极度四个等级,对应的变化范围分别为:2～4、4～8、8～16、>16 dS m-1;土壤钠质化程度分为轻度、中度、重度和极度四个等级,对应的ESP范围分别为:5～10%、10～20%、20～40%、>40%;土壤酸碱性分为酸性、中性和碱性三种,对应pH范围分别为<6.5,6.5～8.5、>8.5。结果表明,植被类型对土壤盐度具有很好的指示作用,按土壤盐度由高到低排列,植被类型的顺序依次为:无植被(碱斑)、碱蓬(Suaeda glauca)、碱茅(Puccinellia tenuiflora)、虎尾草(Chloris virgata)、芦苇(Phragmites australis)、羊草(Leymus chinensis)。碱斑地、碱蓬地、碱茅地和虎尾草地的盐渍土类型均为盐化钠质土(ECe>2 dS m-1,ESP>5%),其中碱斑地和碱蓬地土壤盐化程度为极度(26.54≤ECe≤176.80 dS/m)、钠质化程度为极度(50.22≤ESP≤94.54%);碱茅和虎尾草植被下土壤盐度分别为10.70≤ECe≤27.62 dS m-1和6.86≤ECe≤13.88 dS m-1,钠质化程度分别为30.97≤ESP≤60.26%和16.21≤ESP≤58.11%;芦苇地的盐化程度为1.56≤ECe≤3.37 dS/m,钠质化程度为轻度(7.82≤ESP≤15.88%);羊草地的土壤盐度和钠质化程度分别2.43≤ECe≤6.66 dS m-1和1.43≤ESP≤8.34%。就土壤pH而言,羊草地为中性(7.44≤pH≤8.23),芦苇地为中性和/或碱性(8.18≤pH≤10.02),虎尾草地、碱茅地、碱蓬地和碱斑地均为碱性(8.83≤pH≤10.63)。

Electrical conductivity of soil saturated paste extract （ECe）, exchangeable sodium percentage （ESP） and pH are usually used to determine soil salinity, sodicity and alkalinity, respectively. Soil salinity levels include slight, moderate, severe and extreme corresponding to 2≤ECe 〈 4 dS？m-1, 4≤ECe 〈 8 dS？m-1, 8≤ECe 〈 16 dS？m-1 and ECe≥16 dS？m-1, respectively. Soil sodicity consist of slight, moderate, severe and extreme levels corresponding to 5≤ESP〈10%, 10≤ESP〈20%, 20≤ESP〈40%and ESP≥40%, respectively. The terms acidic, neutral and alkaline were use to denote soils with pH values below 5.5, between 5.5 and 8.5, and above 8.5, respectively. Based on these parameters, 6 salt-affected soils under no vegetation, Suaeda corniculata, Puccinellia tenuiflora,Chloris virgata, Phragmites australis and Leymus chinensis were selected to determine salinity, sodicity and alkalinity properties, respectively. The results showed that the vegetation types could significantly indicate the degree of soil salinization. Arranged from heavy to light according to the degree of soil salinization, the order of vegetation type is alkali patch （no vegetation）, Suaeda corniculata, Puccinellia tenuiflora,Chloris virgata, Phragmites australis and/or Leymus chinensis. Soils under no vegetation, Suaeda corniculata, Puccinellia tenuiflora and Chloris virgata were saline-sodic. The salinity and sodicity of soil under no vegetation and Suaeda corniculata were high and extreme with ECe and ESP range of 26.54-176.80 dS？m-1 and 50.22%-94.54%, respectively. ECe and ESP of soil under Puccinellia tenuiflora and Chloris virgata ranged from 10.70 to 27.62 dS？m-1, 6.86 to 13.88 dS？m-1,30.97 to 60.26%and 16.21 to 58.11%, respectively. Soil with Phragmites australis is slight no-saline and/or saline sodic with 1.56≤ECe≤3.37 dS？m-1 and 7.82≤ESP ≤15.88%. The ECe and ESP of soil under Leymus chinensis ranged from 2.43 to 6.66 dS？m-1 and 1.43 to 8.34%, respectively. With respect to alkalinity, soil under Leymus chinensis was neutral, soil with Phragmites australis was neutral and/or alkaline and the others were alkaline.