Improving N management guidelines in corn (Zea mays L.) production systems can reduce fertilization costs and potential negative environmental impacts. This study was conducted to assess the effectiveness of leaf nitrogen (LN) concentration as a tool to improve midseason N management in corn production. The experiment was conducted on 8 site‐years with furrow irrigation. There were 11 N fertilization regimes with season total N rates ranging from 0 to 257 kg N ha⁻¹. Split‐applications were made at pre‐plant, the 10th collared leaf stage (V10), the 12th collared leaf stage (V12), and tasseling (VT). The uppermost fully collared leaves were sampled at V10 and V12, and ear‐leaves were sampled at VT. Grain yields ranged between 1.6 and 20.7 Mg ha⁻¹, averaging 12.5 Mg ha⁻¹. Relative grain yield (RGY) was positively associated with LN at V10, V12, and VT. Between V10 and VT, a single regression combining data over growth stages was developed between RGY and LN (r² = .82, P value < .0001). Relative grain yield increased linearly as LN increased up to 30.4 g N kg⁻¹ and there was no further increase in RGY when LN was >30.4 g N kg⁻¹. This relationship can be used to improve midseason N fertilization by preventing excessive N fertilization when LN is >30.4 g N kg⁻¹, or by triggering additional N fertilization when LN is <30.4 g N kg⁻¹.

中文翻译：

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玉米中期施肥的叶氮充足水平指南

改善玉米（Zea mays L.）生产系统中的氮管理指南可以降低施肥成本和潜在的负面环境影响。进行这项研究以评估叶氮（LN）浓度作为改善玉米生产中季氮管理的工具的有效性。该实验是在8个位点年进行的沟灌中进行的。共有11种施氮方式，季节总N含量为0至257 kg N ha ^-1。在种植前，第10羽衣阶段（V10），第12羽衣阶段（V12）和流穗（VT）进行了分批施用。在V10和V12采样最上面的全领叶，在VT采样耳叶。谷物产量在1.6至20.7 Mg ha ^-1之间，平均12.5 Mg ha ^-1。相对谷物产量（RGY）与V10，V12和VT处的LN正相关。在V10和VT之间，在RGY和LN之间发展了一个结合了整个生长阶段数据的单回归（r ²  = .82，P值<.0001）。当LN增加到30.4 g N kg ^-1时，相对籽粒产量线性增加，而当LN> 30.4 g N kg ^-1时，RGY没有进一步增加。该关系可用于通过在LN> 30.4 g N kg ^-1时防止过多的N施肥，或在LN <30.4 g N kg ^-1时触发额外的N施肥来改善季中N肥。