不同耕种时间下土壤剖面盐分动态变化规律及其影响因素研究

DYNAMIC OF SOIL SALT IN SOIL PROFILES DIFFERENT IN CULTIVATION AGE AND ITS AFFECTING FACTORS

以新疆奇台县绿洲不同耕种时间土壤含盐量为研究对象,运用聚类分析与相关分析法对其含盐量变化规律、盐分剖面类型及其影响因素进行了研究。结果表明:在荒地转化成人类熟作的农田(5 a以上)过程中,土壤剖面盐分特征变化依次为表聚型、均匀型、震荡型和底聚型。未耕地土壤含盐量高,是典型的盐渍土,且表层聚集现象明显,含盐量在表层(0～20 cm)占整个剖面的34.31%。耕种5 a、10 a的土壤,多为底聚型盐分剖面。随耕种时间加长,土壤各层含盐量的活跃程度变化依次为活跃层、次活跃层和较稳定层;土壤含盐量与有机质含量的关系由极显著正相关转变为极显著负相关,而与土壤pH的关系变化则相反。有耕作活动的土壤盐渍化发生了逆向演替,耕种10 a土壤平均含盐量仅为未耕地的20.90%,脱盐速度随着时间的增加而减小,由早期(0～3 a)的1.56 g kg-1a-1,下降为后期(5～10 a)的0.04 g kg-1a-1。

Salt contents in soils different in cultivation age in Qitai County of Xinjiang were investigated for analysis of rules of the variation of soil salt content, types of soil salinity profiles and their affecting factors, using the cluster analysis method and some other related methods. Results show that along with the transformation of wasteland into farmland （at least 5 years in cultivation history）, characteristics of soil salt content distribution in the soil profiles varied and fell into four types, i.e. surface accumulation profiles （SAP）, even distribution profiles （EDP）, oscillation profiles （OP） and bottom accumulation profiles （BAP）. Uncultivated land high in salt content is typical of salinized soil, with an apparent phenomenon of surface salt accumulation ; and the salt in the surface layer （0 - 20 cm） accounted for 34.31% of the tatol in the soil profile. Farmlands, 5 or 10 years old, are mostly of the type of BAP. With the farming operation going on and on, soil salt content in various salt-containing layers varied in activity degree showing an order of active layer （AL）, subactive layer （SAL） and relatively stable layer （RSL） , and the relationship between soil salt content and soil organic matter content gradually turned from extremely positive one into extremely negative one, while the correlation between soil salt content and soil pH went the other way round. Under farming activities, soil salinization developed reversely. The average salt content in farmlands 10 years old was only 20.90% as much as in wasteland. The desalination rate was reducing with the farming operation going on from 0. 156% a^-1 in the first three years of farming down to 0. 004% a^-1 in the years beyond 5.