Abstract:

【Objective】 To find a more reasonable irrigation system in the dry cotton field area.【Methods】 Field experiments were carried out to study and analyze the dynamics of soil water, heat and salt and the emergence of cotton seedlings after drip irrigation in winter under different irrigation quotas and on the basis of different treatments in the next year. With the flood irrigation quota of 2,250 m³/hm² as the control (CK), four gradient irrigation quotas were designed under the two irrigation modes of drip irrigation(D) and drip irrigation under the control of dry seeding and wet discharge(DG),4 drip irrigation quotais 600, 900, 1,200, 1,500 m³/hm²(D₁,D₂,D₃,D₄); Under the control of drip irrigation in winter, two irrigation quotas of dry seeding(D₁G₁,D₂G₂,D₃G₃, D₄G₄;The Errigation quota of G₁,G₂,G₃ and G₄ is 225(45+180)m³/hm² ) and wet production were 0 and 225(45+180) m³/hm², a total of 9 treatments.【Results】 The results showed that dry-sowing and wet-out could alleviate the sudden change of temperature and soil surface temperature in early spring, and the canal water in early spring would reduce the soil surface temperature by 1-2℃. The dry-sowing and wet-out had a significant impact on the temperature of 10 and 20 cm soil layers. Compared with CK treatment, the temperature of 10-20 cm soil layer after dry-sowing and wet-out treatment increased more gently. Compared with flood irrigation, drip irrigation was more uniform in water infiltration. The larger the irrigation quota of drip irrigation in winter, the more stable the soil temperature would be, the higher the average soil surface moisture content was, and the higher the surface moisture content would be after dry seeding and wetting. After 10 days of treatment, the volume water content of the surface layer with the irrigation quota of D₄G₄(1,500+225)m³/hm² was still higher than that of other treatments. The average water content of the surface layer with the total irrigation amount of D₃G₃(1,200+225) m³/hm² was higher than that of the CK treatment, and the total irrigation amount was 825 m³/hm² less than that of the CK treatment. After dry-sowing and wet-out, the salt leaching effect of the narrow row surface layer was significant. The water infiltration and salt migration areas were concentrated in the 0-30 cm soil layer, and the root system of cotton was mainly distributed in the 0-30 cm soil layer at the germination stage. The larger the winter irrigation quota of drip irrigation, the more obvious the vertical leaching and movement of salt on the soil surface, and the more uniform the soil moisture content, the more likely the salt return phenomenon would be likely to occur. Adding dry seeding and wetting could timely supplement the moisture and suppress the salt return phenomenon. 【Conclusion】 The seedling emergence rate and seedling preservation rate of drip irrigation winter irrigation plus dry seeding are higher than that of drip irrigation winter irrigation only. The seedling emergence rate and seedling preservation rate of irrigation quota of D₃G₃(1,200+225) m³/hm² are higher than that of ordinary flood irrigation.

Key words: cotton; drip irrigation under film; winter irrigation; irrigation quota; dry sowing and wet out

摘要：

【目的】研究滴灌冬灌调控下干播湿出对棉田水盐分布及棉花出苗率的影响。【方法】设置大田试验,以漫灌冬灌2 250 m³/hm²为对照(CK),设计2种灌水模式:滴灌冬灌(D)及滴灌冬灌+干播湿出(DG),4个滴灌定额为600、900、1 200、1 500 m³/hm²(分别记作D₁、D₂、D₃、D₄);滴灌冬灌+干播湿出(分别记作D₁G₁、D₂G₂、D₃G₃、D₄G₄,G₁、G₂、G₃和G₄灌水定额均为225(45+180)m³/hm²)4个处理,2个灌水定额:0、225(45+180) m³/hm²,共9个处理,研究不同灌溉定额下滴灌冬灌及翌年各处理基础上干播湿出后土壤水热盐动态及棉花出苗状况。【结果】干播湿出可缓和早春气温与土壤表层温度的突变,早春渠水会降低土壤表层温度1~2℃,干播湿出对10和20 cm土层的温度影响较为显著,对比CK处理,干播湿出后的处理10~20 cm土层温度升高趋势较为平缓。对比漫灌方式滴灌水分入渗更为均匀,滴灌冬灌灌溉定额越大土温越为平稳,土壤表层平均含水率越高,干播湿出后表层含水率显著增高。灌水定额D₄G₄为(1 500+225) m³/hm²的处理10 d后仍高于其他处理表层体积含水率处理,灌水总额D₃G₃为(1 200+225) m³/hm²的表层平均含水率高于CK处理,总灌水量较CK处理节省了825 m³/hm²。干播湿出后窄行表层盐分淋洗效果显著,水分下渗和盐分运移区域集中在0~30 cm土层,棉花萌芽期根系主要分布在0~30 cm土层。滴灌冬灌定额越大其对土壤表层的盐分纵向淋洗和运移也越明显且土层墒情越均匀,返盐现象也越容易出现,增添干播湿出可及时补墒并压制返盐现象。【结论】滴灌冬灌加干播湿出的出苗率和保苗率要高于仅滴灌冬灌,灌水定额D₃G₃为(1 200+225) m³/hm²的出苗率和保苗率要高于普通漫灌。

关键词: 棉花, 膜下滴灌, 冬灌, 灌水定额, 干播湿出