A well-designed drainage system can alleviate soil salinity and waterlogging, leading to increased crop yield if the drainage does not cause a water shortage late in the growing season. We conducted three field experiments with sunflower across two dry seasons (Experiment I in 2019–20, and II and III in 2020–21) in a tropical landscape to examine the effectiveness of shallow drains and mulch in overcoming these constraints. In Experiment I, four surface drains of 0.1 or 0.2 m depth spaced 1.2 or 1.8 m apart were tested along with an undrained treatment. In Experiment II, the same four drainage treatments and an undrained treatment in the main plots were split into mulch (-M and +M) sub-plots. Experiment III had four main treatments, undrained, surface drains (SD; 0.1 m deep, 1.8 m apart), subsoil drains (SSD; 0.5 m deep, 4.5 m apart) and SSD+SD each split for mulch (-M and +M) sub-plots. At vegetative emergence and at the 8-leaf stage, all plots were inundated (3–5 cm depth; ECw: 1.5–2.5 dS m–1) for 24 h before opening the drains. Drainage treatments without mulch reduced SEW30 (waterlogging index, sum of excess water within 30 cm soil depth) and soil EC1:5 at 0–15 cm, while increasing sunflower yield by 15–100 % compared to the undrained no-mulch treatment. Relative to the undrained no-mulch treatment, drains with straw mulch conserved soil water, reduced EC1:5 at 0–15 cm and increased yield in Experiments II and III by 40–47 and 76–143 %, respectively. There were no yield differences among the combinations of shallow drains. Although combined drains (SSD+SD) added 25–30 % extra yield relative to surface drains, these have higher installation costs. Shallow surface drains at 1.2–1.8 m spacing coupled with mulch are effective options for smallholder farmers to reduce salinity, waterlogging and drought stresses, and increase yield on saline, clay soils.

中文翻译：

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浅排水沟和秸秆覆盖物缓解了多重限制，以提高粘土质地盐渍土壤上的向日葵产量 I. 土壤盐分降低、内涝和季末干旱的影响


设计良好的排水系统可以缓解土壤盐分和内涝，如果排水不会导致生长季节后期缺水，则可以提高作物产量。我们在热带景观中对两个旱季的向日葵进行了三次田间试验（2019-20 年的实验 I，以及 2020-21 年的实验 II 和 III），以检查浅排水沟和覆盖物在克服这些限制方面的有效性。在实验 I 中，测试了四个深度为 0.1 或 0.2 m 的表面排水管，间距为 1.2 或 1.8 m，以及不排水处理。在实验 II 中，主样地中相同的 4 个排水处理和一个不排水处理被分成覆盖（-M 和 +M）子样地。实验 III 有四个主要处理，不排水、地表排水（SD;0.1 m 深，相距 1.8 m）、底土排水沟（SSD;0.5 m 深，相距 4.5 m）和 SSD+SD，分别用于覆盖物（-M 和 +M）子样地。在营养出苗和 8 叶期，所有地块都被淹没（3-5 cm 深;ECw：1.5-2.5 dS m -1） 24 小时，然后打开引流管。无覆盖物的排水处理降低了 SEW30（涝渍指数，30 厘米土壤深度内多余水的总和）和 0-15 厘米处的土壤 EC1：5，同时与不排水的无覆盖处理相比，向日葵产量提高了 15-100%。相对于不排水的无覆盖处理，带有秸秆覆盖物的排水管保留了土壤水分，降低了 0-15 cm 处的 EC1：5，并在实验 II 和 III 中分别提高了 40-47% 和 76-143% 的产量。浅排水管组合之间没有产量差异。尽管组合排水管 （SSD+SD） 相对于表面排水管增加了 25-30% 的额外产量，但这些排水管的安装成本更高。浅表排水量为 1.2-1。8 m 间距加上覆盖物是小农户减少盐分、涝渍和干旱压力以及提高盐碱粘土产量的有效选择。