Abstract:

【Objective】 To explore the effect of winter irrigation on water and salt regulation of saline-alkali soil under irrigation and drainage coordination.【Methods】 Based on field soil box test, two kinds of groundwater depths (G₁ (2 m) and G₂ (3 m)) and two irrigation methods: (W₁ (winter irrigation) and W₂ (non-winter irrigation)) were set, and the freeze-thaw characteristics of soil under different irrigation methods, the characteristics of soil salt return during non-growth period, the efficiency of salt leaching and drainage under winter irrigation combined with irrigation and drainage, and the emergence and seedling growth of cotton were studied.【Results】 Winter irrigation delayed the daily freeze-thaw cycle and daily ablation cycle of soil, and the duration of freeze-thaw and ablation after winter irrigation was shorter than that of non-winter irrigation.With the increase of soil depth, the freezing time lagged behind and the freezing duration became shorter.Winter irrigation could effectively wash the salt of 0-60 cm soil layer, and the salt drainage of 2 m groundwater depth was greater than 3 m.Before sowing in the next year, there was a significant difference in soil salt accumulation between winter irrigation and non-winter irrigation in 0-20 cm soil layer, and the salt of non-winter irrigation was higher than that of winter irrigation.Under the same irrigation method, the surface salt return amount of 2 m groundwater depth was greater than 3 m; at the same underground water depth, the salinity return degree of winter irrigation waS lower than that of non-winter irrigation.There were significant differences in cotton emergence and seedling growth after drip irrigation in the next year, and the emergence rate and seedling growth in the next year after drip irrigation were better than those after drip irrigation.【Conclusion】 Winter irrigation can reduce the soil temperature potential difference at the air-soil interface, reduce the duration of freeze-thaw alternations of 0-20 cm soil, inhibit soil salt return, and promote the growth and survival of cotton seedlings in the next year.Under the coordination of irrigation and drainage, the higher the groundwater depth of underground drainage, the lower the salt carrying efficiency.In the irrigation area, the salinity can be washed into the rising groundwater by winter irrigation, which is characterized by weak diving evaporation and weak salt return.In the spring warming period, groundwater is extracted timely, and the rapid salt return of soil surface is suppressed by reducing the groundwater level, so as to achieve the dual function of inhibiting salt return by drainage irrigation.

Key words: irrigation and drainage coordination; groundwater depth; irrigation in winter; water and salt regulation; cotton

摘要：

【目的】探究灌排协同下冬灌对盐碱土壤的水盐调控效应。【方法】基于野外测箱试验,设置2种地下水埋深:G₁(2 m)、G₂(3 m)和2种灌水方式:W₁(冬灌)、W₂(非冬灌),研究不同灌水方式下土壤冻融特征,非生育期土壤返盐特征,灌排协同下冬灌的盐分淋洗效率、排水排盐效率,棉花出苗及苗期生长状况。【结果】冬灌延迟了土壤日冻融循环和日消融循环,且冬灌后冻融、消融持续时间比非冬灌短。土壤完全冻结期随着土层深度增加在冻结时间上滞后,冻结持续时间变短;冬灌可有效淋洗土壤0~60 cm土层的盐分,且2 m埋深排水排盐量大于3 m;翌年播种前冬灌和非冬灌土壤盐分在0~20 cm土层聚集的差异显著,非冬灌土壤盐分高于冬灌。相同灌水方式下,2 m埋深的表层返盐量大于3 m;相同地下水埋深,冬灌返盐程度低于非冬灌;翌年滴水出苗后棉花出苗及苗期生长差异显著,冬灌后翌年滴水出苗的出苗率和苗蕾期长势优于非冬灌后滴水出苗处理。【结论】冬灌可降低气-土界面土壤温度势差,减少0~20 cm土壤冻融交替持续时间,抑制土壤返盐,翌年滴水出苗更有利于棉花促生保苗。灌排协同下,地下排水埋深越大,排水携盐效率越低;灌区在入冬期可利用潜水蒸发与返盐同步变弱的自然特征,通过冬灌将盐分淋洗至地下水中;春季升温期则适时抽取地下水,通过降低地下水位来抑制土壤表层快速返盐,达到灌排协同控制盐分的目标。

关键词: 灌排协同, 地下水埋深, 冬灌, 水盐调控, 棉花