Proper N management in upland cotton (Gossypium hirsutum L.) is essential to optimize yields. Information on proper N application rate and placement method is needed for coarse‐textured soils of the humid Southeast. The objective of this study was to measure strip‐tilled cotton performance in response to five N rate and placement application methods. Five N rates (0, 45, 90, 135, and 180 kg N ha⁻¹) and three placement methods {broadcast (urea + ammonium sulfate [AMS], surface banded (urea ammonium nitrate [UAN] + ammonium thiosulfate [ATS]), and injected (UAN + ATS) were evaluated from 2016 to 2018 at five sites in Virginia and one site in North Carolina. Petiole NO₃–N, lint yield, lint percent turnout, and fiber quality parameters were measured. Nitrogen rate and placement had a significant effect on lint yield but only N rate affected petiole NO₃–N concentration. Quadratic plateau analysis of relative yield found that 133, 128, and 180 kg N ha⁻¹ were the optimum N rates for injected, surface‐banded, and broadcast systems with relative yields of 95, 90, and 94%, respectively. A critical petiole NO₃–N concentration threshold of 5600 mg NO₃–N kg⁻¹ at early bloom was calculated to reach 92% relative yield. Neither rate nor placement had an effect on fiber quality parameters. This study shows that both surface banding and injecting between 128 and 133 kg N ha⁻¹ can produce 90% or more relative yield for a modern cotton variety in the upper southeastern coastal plain of the United States.

中文翻译：

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东南湿润地区棉花产量和皮棉质量对氮素含量和氮素分配的响应

陆地棉（陆地棉）的适当氮素管理对优化产量至关重要。对于潮湿的东南部粗纹理土壤，需要有关适当氮肥施用量和放置方法的信息。这项研究的目的是测量响应5种氮素施用和施肥方法的条播棉花性能。五个N比率（0、45、90、135和180 kg N ha ^-1）和三个放置方法{广播（尿素+硫酸铵[AMS]，表面结合（尿素硝酸铵[UAN] +硫代硫酸铵[ATS]） ），并于2016年至2018年在弗吉尼亚州的五个地点和北卡罗来纳州的一个地点对注射剂（UAN + ATS）进行了评估。第_3号叶柄测量了–N，皮棉产量，皮棉百分率和纤维质量参数。氮肥的施用量和位置对皮棉产量有显着影响，但只有氮肥施用量会影响叶柄NO ₃ –N的浓度。相对产量的二次平稳分析发现，对于注入，表面结合和播种系统，分别以95％，90％和94％的相对产率分别为133、128和180 kg N ha ^-1是最优的氮肥利用率。计算出初生花粉的临界叶柄NO ₃ -N浓度阈值为5600 mg NO ₃ -N kg ^-1，达到相对产率的92％。速率和放置对纤维质量参数都没有影响。这项研究表明，表面条带化和注入量介于128和133 kg N ha之间^-1可以在美国上东南沿海平原上生产现代棉花品种，产生90％或更高的相对产量。