摘要:
盐结皮是干旱区灌溉后土壤表层形成的一个特殊层次,但目前对其形成条件和时空变化规律尚无系统研究.该文通过对2004和2005年在塔克拉玛干沙漠布置的试验地的调查研究表明,在咸水灌溉林地,土壤表层形成明显的盐结皮层.该文对盐结皮层厚度和电导率这两个主要特征进行了综合分析,得到以下结论:①灌溉水质、灌溉方式、灌水定额、灌水周期以及土壤质地在很大程度上可以影响盐结皮的性质.②盐结皮的性质具有明显的空间分布规律,畦灌和滴灌对林地盐结皮性质的微空间分布影响很大,坡向、土壤结构等立地条件在一定程度上也影响盐结皮性质的空间分布.③盐结皮性质存在明显的时间变化,在灌溉周期内,电导率经历增加→降低→稳定的变化过程,一般在灌溉后5 d盐结皮层开始形成;在年内盐结皮的电导率随着气温的变化而呈明显的月际变化;由于土壤中大气降尘和植物枯枝落叶年复一年的加入而导致土壤表层结构的极大变化,因此随着林地的发育,盐结皮层厚度逐渐趋于稳定,而电导率呈先增加后降低的趋势.
Abstract:
Salt crust is a special layer on soil surface after irrigation in arid zone.But now the research work on its forming conditions and temcporal and spatial rules isn't systematically carried out yet.The experiments carried out in 2004 and 2005 on the forestland irrigated with saline water in the Taklimakan Desert indicated that a significant salt crust layer formed in the topsoil of forestland affer being irrigated.Through surveying the thickness and electrical conductivity(EC) of salt crust layers in all experimental plots,some conclusions are drawn as the followings:1) the degree of minalization of irrigating water,irrigation method,irrigation program(irrigation water quota,irrigation interval) and texture of soil have great effects on the features of salt crust;2) the features of salt crust have a clear spatial distribution.The two irrigation ways,ie ridge irrigation and drip irrigation,have great effects on the micro-spatial distribution of characteristics of salt crust layers in the forestland.Slope aspects and soil texture and structure also have great effects on the distribution of salt crust;3) the temporal changes of salt crust are very significant.In an irrigation period,the EC of surface soil increases firstly,then decreases and levels off,salt crust generally forms since five days after irrigation.The EC of salt crust changes monthly with the variation of air temperature.Because of the dust deposition and litter accumulation on ground surface year by year,which leading to the great changes of topsoil structure, so with the development of forestland,the thickness of salt crust in the ground surface of forestland tends to be stable gradually,while the EC of it increases firstly and then decreases.
百度学术
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