滨海盐荒地不同高度台田地下水动态变化与脱盐效果

Dynamics of groundwater table and soil desalination of platform fields in coastal wasteland

  • 摘要: 为给大面积滨海盐渍荒地农业开发利用提供高效的技术支撑, 在黄河三角洲滨海盐渍荒地上, 设计135 cm、145 cm和175 cm高度台田处理, 以未做台田处理的盐荒地为对照, 定位监测挖深沟修台田后2年的地下水埋深与矿化度的变化动态, 以及连续种植5年后台田土体含盐量的变化。研究表明: 连续2年3种高度台田均能有效增加地下水的埋深, 盐渍荒地地下水埋深变化为0.65~2.10 m, 3种高度台田地下水埋深变化为2.20~3.63 m。3种高度台田的地下水矿化度同盐渍荒地相比均呈现升高趋势, 表明台田土体盐分通过灌溉和降雨作用淋洗进入地下水中。修建台田前荒地0~30 cm土壤含盐量为4.90~7.33 g·kg-1, 台田引黄灌溉洗盐后土壤含盐量降低到1.37 g·kg-1以下, 土壤脱盐率为81.31%~89.05%。连续种植5年后, 不同高度台田0~120 cm土体盐分含量均低于盐荒地, 尤其0~30 cm和30~60 cm土层的盐分含量与盐荒地相比降低显著; 其中135 cm和145 cm台田各土层盐分含量均小于1.62 g·kg-1。因此, “台田?深沟”模式是改良滨海重度盐渍土的一种有效工程措施, 考虑到开发成本和台田有效面积比, 台田高度可优先选择145 cm。

     

    Abstract: In this study, 135 cm, 145 cm, and 175 cm high platform fields were built on coastal saline wastelands in the Yellow River Delta. The dynamics of groundwater table were monitored over a period of 2 years and changes in soil salt content after 5 years crop cultivation were determined, with natural saline wastelands as the control. The main objective of the study was to provide data-driven technical support for large-scale agricultural development in coastal saline soils. The results of the 2-year consecutive monitoring showed that the three platform fields effectively increased saline water table. Groundwater table in saline wastelands changed in the range of 0.65~2.10 m, while those in the three platform fields changed in the range of 2.20~3.63 m. Compared with saline wastelands, groundwater salinity of the three platform fields significantly increased. This suggested that salts in platform fields leached from soil profile to groundwater via both irrigation and rainfall. Salt content in the 0~30 cm soil layer was 4.90~7.33 g·kg-1 in saline wastelands, which significantly dropped to <1.37 g·kg-1 after platform field development and irrigation. Desalination ratio of the platform fields was 81.31%~89.05%. Salt content in the 0~120 cm soil layer of the platform fields was lower than those of saline wastelands after 5 years cultivation. The differences in soil salt content between platform field and control field in both 0~30 cm and 30~60 cm soil layers were significant. Soil profile salt content in the 135 cm and 145 cm platforms was <1.62 g·kg-1. The results indicated that “platform field-deep ditch” was an effective engineering measure to ameliorate salinity in coastal wastelands. In terms of cost and effective area ratio, the 145 cm high platform field was recommended the best practice for coastal wasteland desalination.

     

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