Abstract Selection of a suitable low-pressure sprinkler can be an effective measure to reduce energy consumption, wind drift and evaporation losses. The crop canopy often redistributes the applied water during sprinkler irrigation. Therefore, we investigated the water distributions above and below the canopy as well as their differences in Heermann and Hein uniformity coefficient (CUH) under three commonly used sprinkler types (Nelson D3000, Nelson R3000, and Komet KPT) and two growth stages of summer maize (6-leaf stage and tasselling stage) to evaluate the effect of crop canopy on the water distribution of low-pressure sprinklers. The variations in the soil water content (SWC) and Heermann and Hein uniformity coefficient of soil water content (CUHS) were investigated further at 1 h before, 1 h after, and 24 h. Additionally, the effects of growth indices and sprinkler types on CUH and CUHS values were analysed. Both the water application depths and CUH values above the canopy were significantly higher than those below the canopy and the differences above and below the canopy increased significantly with the growth of maize. The CUHS after irrigation mainly depended on the initial SWC and CUHS values but was minimally correlated with the plant height, leaf area index, and sprinkler application uniformity. Although the CUH above the canopy (78.1%) of D3000 was significantly lower than R3000 and KPT sprinklers (both exceeding 90%), the CUHS of D3000 reached more than 93% after irrigation. This result indicated that the effect of sprinkler application uniformity was not important as predicted, and a good CUHS would be achieved after canopy interception and soil water redistribution irrespective of sprinkler types. This study provides an insight into the selection of best low-pressure sprinklers in centre pivot irrigation systems.

中文翻译：

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受中央枢轴灌溉系统下玉米冠层影响的低压喷头的水分布

摘要 选择合适的低压喷头是减少能耗、风漂和蒸发损失的有效措施。在喷灌过程中，作物冠层经常重新分配施加的水。因此，我们研究了三种常用喷头类型（Nelson D3000、Nelson R3000和Komet KPT）和夏玉米两个生长阶段下冠层上方和下方的水分分布及其Heermann和Hein均匀系数（CUH）的差异。 （6叶期和抽穗期）评价作物冠层对低压喷头布水的影响。在前 1 小时、后 1 小时和 24 小时，进一步研究了土壤含水量 (SWC) 以及土壤含水量的 Heermann 和 Hein 均匀系数 (CUHS) 的变化。此外，分析了生长指数和喷头类型对 CUH 和 CUHS 值的影响。冠层以上的施水深度和CUH值均显着高于冠层以下，且冠层上下差异随着玉米的生长而显着增大。灌溉后的 CUHS 主要取决于初始 SWC 和 CUHS 值，但与株高、叶面积指数和喷水均匀度的相关性最小。虽然D3000冠层以上CUH（78.1%）明显低于R3000和KPT喷头（均超过90%），但D3000灌溉后CUHS达到93%以上。该结果表明喷头喷洒均匀性的影响并不像预测的那样重要，无论洒水喷头类型如何，在树冠拦截和土壤水分重新分配后都将实现良好的 CUHS。这项研究提供了对中心枢轴灌溉系统中最佳低压喷头的选择的深入了解。