不同气候带海水灌溉下滨海盐土水盐运动特征

Characteristics of Hydrosalinity Balance on Three Different Type of Coastal Saline Soils under Seawater Irrigation

自2001年开始,采用田间试验与室内模拟相互验证的方法,对山东莱州(暖温半干旱带)、江苏大丰(暖温湿润带)、海南乐东(热带湿润带)进行了海水灌溉下滨海盐土水盐运动特征研究,结果表明:(1)各气候带适宜的灌溉定额下,未作任何人为调控措施,半干旱的莱州虽呈自然积盐的趋势,但即使用50%的海淡水混灌,2年0～60cm土层盐分仍未超过3‰,江苏大丰用60%的海淡水灌溉,海水灌溉携入的总盐量与1m土体淋失的盐量持平,而海南乐东盐分收支平衡的海淡水比例为75%;(2)在半干旱的山东莱州,0～60cm各土层含盐量变幅起伏较大,表明蒸发为盐分运动的控制因子,而在湿润的江苏大丰,30cm以下土层含盐量平稳,地下水控制盐分运动的作用增强。两个气候带,在整个夏季,各海水灌溉处理表层土壤含盐量明显低于下层土壤;(3)海水灌溉明显降低土壤水吸力,表明海水灌溉可以缓解土壤水的蒸发,越是干旱,这种作用越明显。

During the two years of 2001 and 2002, field experiments and simulating trials were conducted to study hydrosalinity balance on different type of coastal soils(respectively situated in Laizhou region of Shandong province, Dafen region of Jiangsu province, and Yuedong region of Hainan province) under seawater irrigation. The results showed that, irrigated with suitable amounts of blended water with different salinity level, the soil profile in Laizhou had a trend to accumulate soluble salts, but when using the blended water with salinity level of 20 ds/m, total salt in 0~60 cm soil layer was also less than 0.3%. In Dafen region and Yuedong region, respectively irrigated with blended water of 24 ds/m and 30 ds/m, total salt in 1 m soil mass obtained hydrosalinity balance. In semiarid region of Laizhou, total salt in 0~60 cm soil layer fluctuated a bit, implicated that evaporation played a dominant role in salt and water movements. While in humid region of Dafen, total salt below the 30cm of soil layer maintained rather stable, which indicated that stable ground water table mainly influenced salt and water movements. In the experiments of seawater irrigation, the result also showed that total salt in upper soil layers was less than that in deeper soil layers in varying treatments during the summer. In the study of water-contained characteristics of the coastal saline soils, we found that seawater irrigation could reduce soil suction, that is, seawater irrigation could render the soil keep more water for plant utilization, especially for halophytes.