喷灌强度对滨海盐碱地土壤水盐运移特征的影响

为研究一维条件下喷灌强度对滨海盐碱地土壤湿润峰运移、水分再分布特征及盐分淋洗的影响,选用滨海盐碱地黏质重度盐碱土和砂质重度盐碱土2种土壤,设置5个喷灌强度(分别是1.72、3.13、5.27、8.75、10.11mm/h),进行室内喷灌条件下土柱模拟试验。结果表明,喷灌强度与土壤黏粒含量显著影响湿润锋运移。湿润锋推进速度随着喷灌强度增加而增大,而湿润深度随之减小,且土壤黏粒含量越高,越不利于湿润锋运移;随着土壤水分再分布过程的推进,黏质重度盐碱土在3.13mm/h喷灌强度下同一深度体积含水率较其他处理大,砂质重度盐碱土在1.72mm/h喷灌强度条件下土柱具有较高的保水性;采用喷灌淋洗,可使上层土壤脱盐,盐分均累积至下层土壤,并使其急剧增加且达到最大值。对于黏质重度盐碱土,3.13mm/h喷灌强度下,盐分淋洗效果较好,而对于砂质重度盐碱土,8.75mm/h喷灌强度淋洗效果优于其他处理。该研究可为喷灌技术合理和可持续开发利用滨海盐碱地提供参考。

Effect of watering intensity on characteristics of water and salt movement under sprinkle irrigation in coastal soil

Abstract: Sprinkler irrigation, as one of the useful technologies for the development and utilization of saline soils, has been extensively used in coastal saline soils. However, few studies have been related to the effects of water application intensity on movement of water and salt transport under sprinkle irrigation in this region. A soil-column experiment was carried out to investigate the effects of water application intensity on the movement of wetting front, water redistribution characteristics and salt leaching of coastal highly-saline soil. The experiments included two kinds of coastal highly-saline soils (clayey and sandy) and five water application intensity treatments, in which the sprinkle irrigation was controlled at 1.72, 3.13, 5.27, 8.75 and 10.11 mm/h, respectively. The results showed that under sprinkle irrigation, the water application intensity and soil clay content significantly influenced the movement of the soil-wetting front. With the increase of water application intensity, the driving velocity of the wetting front increased, while the moist depth decreased. To some extent, the soil clay content had a negative effect on the movement of the wetting front. With the redistribution of the soil moisture, the volumetric moisture content of the same depth was largest at the water application intensity of 3.13 mm/h in clayey highly-saline soil, while in sandy highly-saline soil, the most optimal water preserving capability was observed at the water application intensity of 1.72 mm/h. After sprinkler irrigation, the salts in the upper soil layer were well leached, and moved down to the subsoil, where the soil salt content increased sharply to reach maximum. The suitable water application intensity of sprinkler irrigation was different on these two kinds of soils. Among the five treatments, the best leaching effect was obtained at the water application intensity of 3.13 mm/h in clayey highly-saline soil, and 8.75 mm/h in sandy highly-saline soil. This research is meaningful for completing sprinkler irrigation technology to best utilize coastal saline soil, and it will provide a theoretical basis and technical support for developing a complete and systematic technology of water-salt regulation by sprinkler irrigation.