黄河三角洲盐渍土蒸发对土壤盐分变化的响应特征

为了探明黄河三角洲盐渍土蒸发对土壤盐分变化的响应特征,采用矿化度分别为5,10,30,50,70,90 g/L的咸水灌溉黄河三角洲0~40 cm土壤,获得不同盐分梯度的盐渍土处理,依次标记为处理T1—T6,并测定各处理的土壤含水率和电导率、蒸发强度和累积蒸发量等指标.结果表明,蒸发过程中表层土壤含水率和电导率均随土壤含盐量增加呈逐渐增加趋势;蒸发结束时,处理T1—T6的土壤表层平均含水率比试验初期降低了80.0%~95.8%,表层含水率的降低幅度随着含盐量增加而逐渐降低;土壤表层电导率分别增加135%~330%,且蒸发前期表层电导率增加幅度明显高于蒸发后期.土壤含盐量对土壤剖面含水率及电导率分布影响差异具有统计学意义,蒸发结束时,处理T1—T6表层0~2 cm比3~6 cm土壤含水率低了8.3%~30.5%,土壤电导率则高了82%~196%,且随着土壤含盐量增加,盐分对土壤剖面盐分分布的影响逐渐增强,表层与深层土壤含盐量差异逐渐增大.蒸发过程中,土壤平均蒸发强度和累积蒸发量随土壤含盐量增加呈降低趋势,处理T1—T6的平均蒸发强度为3.5×10^-4,3.5×10^-4,3.4×10^-4,3.2×10^-4,3.0×10^-4和2.7×10^-4 mm/d,土壤累积蒸发量分别为26.13,26.20,25.50,24.26,22.50和20.58 mm,且蒸发前期各处理的土壤平均蒸发强度及累积蒸发量均高于蒸发后期,土壤含盐量对土壤蒸发的抑制作用主要在蒸发前期.研究表明土壤含盐量可影响土壤剖面含水率与电导率分布以及土壤蒸发强度和累积蒸发量.

Response characteristics of saline soil evaporation in Yellow River Delta under different salinity levels

In order to explore the response characteristics of soil evaporation in the Yellow River Delta under different salinity levels, saline water with salinity of 5, 10, 30, 50, 70, and 90 g/L were utilized to irrigate the 0-40 cm soil(which were labeled T1—T6 in turn)in the Yellow River Delta. And soil moisture treatment with different salinity gradient is marked as treatment T1—T6 in turn. The soil water content, electrical conductivity, evaporation intensity and cumulative evaporation were measured during the experimental period. The results showed that the surface soil moisture and electrical conductivity increased gradually with the increase of soil salt content during evaporation process. At the end of evaporation, the average water content of soil surface layer treated with T1—T6 was 80.0%-95.8% lower than that at the beginning of the experiment. The soil electrical conductivity of the surface layer increased by 135%-330%, and the electrical conductivity increase of soil surface during the early evaporation stage was significantly higher than that during the later stage. The distribution of soil moisture and electrical conductivity were significantly effect by soil salt content. At the end of evaporation, the soil moisture content of 0-2 cm surface layer of T1—T6 treatments were 8.3%-30.5% lower than that of 3-6 cm, while the electrical conductivity of 0-2 cm for T1—T6 treatments were 82%-196% higher than that of 3-6 cm. The difference between surface and deep layer for soil salt content gradually increased with the increase of soil salt content. During the evaporation process, the average soil evaporation intensity and cumulative evaporation decreased with the increase of soil salt content, and the average evaporation intensity of T1—T6 treatment were 3.5×10^-4, 3.5×10^-4, 3.4×10^-4, 3.2×10^-4, 3.0×10^-4 and 2.7×10^-4 mm/d, and the cumulative evaporation were 26.13, 26.20, 25.50, 24.26, 22.50 and 20.58 mm respectively. The average evaporation intensity and accumulated evaporation of each treatment in the early stage of evaporation were higher than those in the late stage of evaporation. The inhibitory action of soil salt content on soil evaporation was mainly in the early stage of evaporation. The results showed that soil salinity could affect the distribution of soil moisture and electrical conductivity, as well as soil evaporation intensity and cumulative evaporation.