The central temperate Argentinean region is currently affected by rising water tables, allowing higher and more stable maize yields (Zea mays L) when they fluctuate within optimum depth. However, limited information was available for optimizing N management in these environments. Yield response to N rates was explored in soils with influencing groundwater (always <3.5 m depth), and different environment and management variables were examined to help explain differential yield responses across sites. A total of 15 rainfed experiments (site × year combinations) were conducted with five N rates (0–240 kg N ha⁻¹) tested at two different timings (sowing and V7) in a factorial design. A consistent yield response to N rate was evident, increasing yields from 2,300 to 6,900 kg ha⁻¹ across sites. Yields at maximum N levels ranged from 13,700 to 16,900 kg ha⁻¹. Fertilization timing had a minor and inconsistent effect on yield across sites. At a maize grain/fertilizer N price ratio of 10, the economically optimal N rate ranged from 117 to 206 kg N ha⁻¹. Soil N‐NO₃ at sowing, previous crop, and apparent–indigenous N supply (INS) helped explain differential yield responses across sites, and response models for obtaining economic optimum rates considering the influence of these variables are provided. These results highlight the relevance of N rate, rather than timing, as a critical crop management decision in environments with high water availability and yield.

中文翻译：

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在最佳深度影响地下水位的土壤中的玉米氮素管理

阿根廷中部温带地区目前受到地下水位上升的影响，当玉米在最佳深度波动时，玉米单产（玉米）将更高，更稳定。但是，在这些环境中，仅有有限的信息可用于优化N管理。在有地下水影响的土壤（始终<3.5 m的深度）中探索了对氮含量的产量响应，并研究了不同的环境和管理变量以帮助解释各地间不同的产量响应。在因子设计中，在两个不同的时间点（播种和V7）测试了五个氮素含量（0–240 kg N ha ^-1），总共进行了15个雨养试验（部位×年组合）。很明显，对氮的产量有一致的响应，使产量从2,300千克公顷增加到6,900千克公顷^-1在站点之间。最高氮水平时的产量为13,700至16,900 kg ha ^-1。施肥时间对站点间的产量影响较小且不一致。在玉米/肥料氮价格比为10时，经济上最佳的氮施用量为117至206 kg N ha ^-1。播种时的土壤N-NO ₃含量，先前的作物以及表观的本地氮供应（INS）有助于解释不同地点的单产差异响应，并提供了考虑这些变量影响而获得经济最优比例的响应模型。这些结果突显了氮素含量的相关性，而不是时间安排，这是在水资源利用率高和产量高的环境中作为作物管理的关键决定。