膜下滴灌间作盐生植物棉田水盐运移特征及脱盐效果

盐生植物改良盐碱地作为改良盐碱地最有效的方法之一,具有成本低,效率高,环境友好等特点,有良好的应用前景。该文包括2个研究目标:1)研究间作不同盐生植物的膜下滴灌棉田水盐运移特性;2)研究不同地下水埋深条件下盐生植物的盐碱地改良效果。针对第1个研究目标,设置了3种(孜然、碱蓬、苜蓿)间作盐生植物,进行大田试验,分析地下水埋深相似条件下间作不同盐生植物时土壤水盐分布状况;针对第2个研究目标,设置了4种地下水埋深(1.5、2.0、2.5、3.0 m),进行均衡场试验,研究不同地下水埋深条件下间作盐生植物时地下水的补给比例和土壤脱盐效果。结果表明:1)膜下滴灌棉田间作盐生植物能明显提高棉花生育期膜间和膜内0~30 cm土层平均含水率,且碱蓬效果最明显;间作条件下苜蓿、碱蓬、孜然、对照0~100 cm土层平均脱盐率依次为55.97%、-18.77%、-21.43%、-307.52%,即苜蓿的总脱盐率效果最好;间作盐生植物能在一定程度上抑制0~100 cm土层钠离子和氯离子的聚集,同时增加棉花产量和提高其水分利用效率,且碱蓬对抑制盐离子累积的效果最好;2)间作条件下,地下水埋深越浅,0~100 cm土层平均含水率越高,膜内膜间的含水率差异越小,土壤的脱盐率越低。与未间作相比,间作种植有效的提高了土壤脱盐率,增加了棉花产量、提高了地下水补给比例和水分利用效率。可见,膜下滴灌棉田间作盐生植物不仅可以有效降低土壤含盐量,增加其含水率,还可以增加棉花产量和提高其水分利用效率,且间作碱蓬和苜蓿的节水、脱盐、增产效果较好,这为膜下滴灌土壤盐碱地改良提供了有效的理论支撑。

Water and salt transport and desalination effect of halophytes intercropped cotton field with drip irrigation under film

Abstract: Improvement of saline-alkali soil by halophyte is one of the most effective methods, which has good application prospect such as low cost, high efficiency and environment friendliness. Large amounts of saline-alkali soils and severe drought significantly restricts sustainable development of irrigated agriculture in the Xinjiang region. However, long-term application of the irrigation method will face the potential risk of salinization. Thus, the paper''s aim was to explore the characteristics of water and salt transport in field soil and halophytes''s desalinization effect in saline-alkali soil under the intercropped cotton systems under the drip irrigation with film. The experiment was carried in field and water balance spot. In the field experiment, the groundwater depth was not adjusted and 3 kinds of halophytes (alfalfa, Suaeda and cumin) were used. The treatment without halophytes was considered as the control. In the water balance spot experiment, the Suaeda was intercropped with cotton and 4 kinds of groundwater depths (1.5, 2.0, 2.5, 3.0 m) were designed. The soil moisture, salinity, sodium and chloride ion content, cotton yield and groundwater recharge were determined. The results showed that halophytes intercropped with cotton could significantly increase the average soil moisture at 0-30 cm depth between the film and inside film during the growth stage of cotton in field, and the treatment with intercropping Suaeda was the most effective. The average soil desalinization rate of intercropping alfalfa, Suaeda, cumin and the treatment of no intercropping in soil at 0-100 cm depth was 55.97%, -18.77%, -21.43%, -307.52%, respectively. The treatment with intercropping alfalfa was the most effective to remove salt from soil. The desalination rate in the narrow rows was the highest and that between the film was the lowest; Intercropping halophytes could decrease the content of sodium ions and chloride ions to a certain extent in soil at 0-100 cm depth, and increase the cotton seed yield and water use efficiency. Among the treatments, intercropping alfalfa was the best for decreasing sodium ions and chloride ions content of the field soil. The trial of water balance spot showed that the smaller the groundwater depth was, the higher the average soil moisture was, and the smaller the moisture difference inside film and between films in soil at 100 cm depth under intercropping conditions was. Compared with no intercropping, the intercropping treatments could effectively reduce soil salinity, increase the soil moisture, increase the cotton yield and improve the water use efficiency. In addition, the intercropping treatments increased the groundwater recharge ratio. Among all the treatments, the intercropping Suaeda and alfalfa had the best effect. We suggested to improve saline soil by intercropping Suaeda with cotton under the drip irrigation with film since the intercropping Suaeda with cotton had the better inhibition effect for sodium ion accumulation than the intercropping alfalfa treatment. These results will provide the support for saline alkali soil improvement with drip irrigation under film and the sustainable application for the irrigation method in saline alkali soil and arid region.