奇台县绿洲农田土壤盐渍化逆向演替过程

Reversal Evolvement of Farmland Soil Salinization in Qitai Oasis

在奇台县绿洲中部平原区和绿洲沙漠交错带选择不同耕种时间的农田,分析其剖面土壤可溶性总盐、pH值、有机质含量随耕种时间的变化。研究表明:奇台县绿洲地下水位已低于影响地表盐渍化的水位临界值(5 m),地下水矿化度低于3 g/L,研究区整体处于有利于土壤盐渍化逆向演替的环境。随着地下水位的不断下降以及耕种时间的延长,农田土壤含盐量逐渐减少,土壤有机质逐渐增加,土壤盐渍化逆向演替过程已经发生。土壤盐渍化的逆向演替过程具有时空特征,可以划分为初级、中级、高级3个阶段。由绿洲下部向上部,土壤盐渍化逆向演替阶段逐渐向高级过渡。

Choosing farmlands of different cultivated time in plain and oasis-desert ecotone in Qitai oasis, analyzes the temporal movement of soil soluble total salt, pH value, organic matter. The results show that Qitai oasis has already in a circumstance which is valuable for soil-salinization reversal evolvement, groundwater table is below 5 meters, the critical point which will affect the surface salt accumulation. Groundwater mineralization degree is lower than 3 g/L. With the decreasing of groundwater table and the increasing of cultivated time, the content of soil soluble total salt declined and organic matter enhanced, soil-salinization reversal evolvement has already occurred. Salinization reversal evolvement presents temporal and spatial characters, and can be classified as three different phases; the primary, the middle and the high-level. From the lower to the upside of Qitai oasis, the stage of soil salinization reversal evolvement gradually transfers to high-level.