膜下滴灌玉米番茄间作农田土壤水分分布特征模拟

    Soil moisture distribution characteristics simulation of maize-tomato intercropping field with drip-irrigated under plastic mulch

    • 摘要: 间作种植和覆膜滴灌是实现高产和节水的重要技术,已被广泛应用,而掌握覆膜滴灌条件下间作种植农田土壤水分分布特征对于提高水分利用效率以及增产增收都具有重要意义。该文通过2 a田间试验设置高(T1)、中(T2)、低(T3)3个灌水定额处理,并通过HYDRUS2D模型模拟了间作滴灌农田不同位置土壤水分的差异性、水平水量交换以及土壤水分二维分布特征。结果表明:基于HYDRUS2D构建的间作种植滴灌农田土壤水分模型精度较高,平均相对误差为5.72%~8.14%,决定系数在0.85~0.90,均方根误差在0.017~0.023 cm3/cm3。对于3个灌水处理皆表现为0~40 cm 土层含水率出现差异,且在0~20 cm土层含水率差异显著,2014年番茄侧和玉米侧土壤含水率在3个灌水处理下的平均土壤含水率分别较裸地高20.17%和17.83%,2015年为16.02%和12.99%。间作滴灌农田土壤水平水量交换强烈,生育期水流主要由作物侧流入裸地侧,其中对于3个灌水处理在番茄侧0~40 cm土层净流入裸地的平均水量是玉米侧的1.3倍,约为60 mm/a,并且0~40 cm土层由作物侧流入裸地的水量是>40~100 cm土层的2.5倍。二维土壤水分分布显示,滴灌湿润体与作物根系分布匹配性较好,灌水后1d湿润饱和区主要集中在0~30 cm土层,其中T1、T2、T3处理的饱和区面积分别为559.14,288.61和109.78 cm2。灌水2 d后,低灌水处理(T3)存在较明显的水分亏缺,缺水区面积是充分灌溉(T1)的30倍。研究结果可为间作滴灌农田制定灌溉制度提供参考。

       

      Abstract: Abstract: Intercropping and drip irrigation with plastic film is widely applied in North China and appears to be an important technique for gaining high crop yield. Further understanding the soil water distribution is important to increase the water use efficiency (WUE) and crop yield under drip-irrigated intercropping field. A 2-year experiment (2014 and 2015) was conducted including high (T1), middle (T2) and low (T3) irrigation quota, and the soil water difference for different locations, horizontal soil water exchange and 2-D soil water distribution were simulated by HYDRUS2D model in an drip-irrigated intercropping field. The results showed that hydraulic model for drip-irrigated intercropping field base on HYDRUS2D software had good accuracy, and the mean relative error (MRE) and root mean error (RMSE) and high value of determination coefficient (R2) were in range of 5.72%-8.14%, 0.017-0.023 cm3/cm3, and 0.85-0.90, respectively. There was significant difference among different locations under drip-irrigated intercropping field in 0-40 cm soil layer, especially for 0-20 cm. The average soil water content (SWC) in tomato and corn sides being about 20.17% and 17.83% higher than at the between 2 crops respectively in 2014, and being about 16.02% and 12.99% in 2015. The soil water flux moved horizontally from crop sides to between 2 crops during crop growth period. The soil water amount form tomato side to bare area was 1.3 times of that of corn side, was about 60 mm/a, and the soil water exchange in 0-40 cm layer was 2.5 times of that in 40-100 cm layer. Compared with the treatment of low irrigation quota, high irrigation quota and middle irrigation quota increased by 2 times and 1.5 times respectively, while the amount of water flowing into bare area in 0-40 cm layer increased by 1.75 times and 1.3 times respectively, based on the direct proportion relationship. The 2-D soil water distributions for different irrigation treatments showed drip soil wetting pattern was well agreement with crop root distribution. The saturated zone mainly concentered in 0-30 cm layer in irrigation after 1 day, and the areas for high, middle and low irrigation quota treatments were 559.14, 288.61 and 109.78 cm2, respectively. The water stress zone was found in 30-40 cm soil layer in irrigation after 2 days. When the amount of irrigation water was reduced in treatments middle and low irrigation quota treatments, the water stress zone increased in size. The size of the water stress zone was about 129.86 cm2 for treatment of high irrigation quota that resulted in negligible stress on root water uptake. The water stress zone was about 1 663.29 cm2 for treatment of middle irrigation quota that caused a slight restriction of the crop growth. On the other hand, the water stress zone was about 3 883.94 cm2 for treatment of low irrigation quota, which created a significant influence to crop growth. There was obvious water stress for low irrigation quota treatment after 2 days, and the area for soil water deficit in treatment of low irrigation quota was 30 times than high irrigation quota. The researches provide the information for making irrigation scheduling under drip-irrigated intercropping field.

       

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