间歇组合灌溉对中度盐化土壤水盐运移规律的影响研究

为了探究合理的微咸水农田灌溉模式,以中度盐化土壤为研究对象,在室内进行一维垂直积水入渗试验,研究不同咸淡水组合次序和间歇时间条件下土壤水盐运移规律,并对土壤盐分分布指标进行评价。结果表明:(1)间歇组合灌溉模式下各土层的土壤含水率均大于淡水直接灌溉,且与微咸水直接灌溉差异较小;先咸后淡土壤含水率变异系数介于9.24～16.62之间,相对于先淡后咸(11.54～20.88),土壤含水率分布更均匀。(2)在同一土层深度处,间歇组合灌溉模式下的土壤含盐量均小于微咸水直接灌溉,与淡水灌溉差异较小;在0～20 cm土层,先淡后咸土壤含盐量大于先咸后淡,而在20～55 cm土层,先咸后淡大于先淡后咸。(3)对土壤盐分评价指标进行分析表明,先咸后淡含盐量峰值大于先淡后咸;先淡后咸脱盐率平均值大于先咸后淡;在间歇组合灌溉模式下,脱盐区深度介于47.97～51.63 cm、达标脱盐区深度介于46.6～50.7之间,均超过了0～45 cm作物根系密度较大的土层;脱盐率平均值(0.36～0.543)、含盐量峰值(3.741～5.967)均高于微咸水直接灌溉,间歇组合灌溉更有利于为作物提供良好的生长环境。

Effects of alteration irrigation on soil water and salt transport in moderately saline soil

One dimensional vertical infiltration experiments were carried out to explore characteristics of water and salt transport in soil under alteration irrigation (AI)in moderately saline soil and evaluate the indexes of salinity distribution. The results showed that: (1)The soil water content with the AI treatment was higher than that with sole freshwater irrigation (F), but slightly differed from that of the sole brackish water irrigation (B). The variation coefficients of soil water content in soil after the irrigation sequence of brackish water irrigation followed by fresh water (B-F) varied from 9.24 to 16.62, which were less than that of irrigation of fresh water first followed by brackish water (F-B):(2)Within the same soil depth, the soil salinity content of treatment AI was less than that of treatment B, but slightly differed from treatment F.In the top 20 cm soil layers, the soil salinity content of treatments F-B was greater than that of B-F, but in 20~55 cm soil layers, the soil salinity content of treatments B-F was greater than that of F-B; (3)The analyses of the evaluation indexes of salinity distribution in dicated that the peak value of soil salinity of treatment B-F was greater than that of F-B. The soil desalination zone varied from 47.97 to 51.63 cm depth and the complied desalination zone varied from 46.6 to 50.7 cm, which was deeper than depth of dense crop roots (0~45 cm). The average desalination rate (0.36~0.543) and the peak value of soil salinity (3.741~5.967) in treatments ICI were higher than that in B, indicating that the ICI is more favorable than other irrigation methods to provide suitable soil water-salt environment for crops growth.