Alternative methods of rice (Oryza sativa L.) irrigation are gaining increasing popularity across the U.S. Mid‐South, but an allowable soil moisture deficit stress has not been defined. This study was conducted in 2018 and 2019 to determine the soil moisture threshold for furrow‐irrigated rice (FIR) and alternate wetting and drying (AWD) rice production systems to minimize irrigation water use while maximizing grain and milling yield. Soil moisture thresholds of −15, −30, and −45 kPa, as determined by Watermark sensors at a 10‐cm depth in the top third of the field, were compared with conventional flood rice (CFR) on a Calloway silt loam and a Sharkey clay in eastern Arkansas. Soil moisture threshold had no effect on grain or milling yield across irrigation thresholds; however, the bottom third of FIR, where a flood was held, consistently produced higher grain yield (10,652–10,965 kg ha⁻¹) than the top third (9,442–9,722 kg ha⁻¹). Significant differences in irrigation water use efficiency (IWUE) were achieved under AWD and FIR. The IWUE did not differ across AWD irrigation thresholds but was 58.1–103.8% greater than that of CFR. The −15 and −30 kPa FIR thresholds did not improve IWUE, but using a −45 kPa irrigation threshold resulted in a 42.7% greater IWUE than CFR and 66.0% greater than the −15 kPa threshold. Results suggest that using a −45 kPa irrigation threshold at the 10‐cm depth can potentially maintain grain and milling yield while increasing IWUE under AWD and FIR.

中文翻译：

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使用土壤湿度阈值安排水稻灌溉以进行沟灌和间断性洪水

水稻的替代方法（Oryza sativaL.）灌溉在美国中南部越来越受欢迎，但尚未定义允许的土壤水分亏缺压力。这项研究于2018年和2019年进行，旨在确定沟灌水稻（FIR）和交替湿润和干燥（AWD）水稻生产系统的土壤水分阈值，以最大程度减少灌溉用水，同时最大化谷物和制粉产量。通过水印传感器在田地顶部三分之一处10 cm深度处确定的土壤湿度阈值-15，-30和-45 kPa，与在Calloway淤泥壤土上的常规洪水稻（CFR）进行了比较。 Sharkey黏土在阿肯色东部。在整个灌溉阈值范围内，土壤水分阈值对谷物或磨粉产量没有影响；但是，发生洪水的FIR的底部三分之一始终产生较高的谷物产量（10,652-10,965千克公顷^-1）比前三分之一（9,442–9,722 kg公顷^-1）高。在AWD和FIR下，灌溉用水效率（IWUE）出现了显着差异。IWUE在AWD灌溉阈值之间没有差异，但比CFR大58.1–103.8％。FIR阈值-15和-30 kPa不能提高IWUE，但灌溉阈值使用-45 kPa时，其IWUE值比CFR高42.7％，比-15 kPa阈值高66.0％。结果表明，在10 cm深度使用−45 kPa灌溉阈值可以潜在地维持谷物和磨粉产量，同时在AWD和FIR下增加IWUE。