In recent decades, continuous increase of N fertilizer inputs made significant contributions to the wheat production increase in the Huang-Huai-Hai Plain, the largest wheat producing region of China. However, gradually the use efficiency of N fertilizer decreased, and the increasing N rate led to a series of environment problems. A better quantitative understanding of the fates of basal N and topdressing N under water-nitrogen interactions in a wheat-soil system is essential to increase yield and reduce environmental impacts. We conducted two-year wheat experiments combining field plots and micro-plots with the ^l5N-labeled method under two irrigation regimens (rainfall, irrigation in jointing and anthesis) and three N rates (0, 180, and 270 kg ha⁻¹). The results showed that 54.9%− 70.4% of total wheat N accumulation was from soil native N, while 29.6%− 45.1% was from fertilizer N. Irrigation at joint and anthesis has increased wheat N accumulation more from fertilizer N than from soil native N. Compared with rainfed condition, irrigation significantly increased plant NNI at booting and anthesis. The contribution of pre-anthesis N translocation to grain N was 80.6%− 86.0%, and increased with increasing total N rate, but decreased with irrigation. The fertilizer N recovery rate increased as N rate and irrigation increased, and more N recovery occurred during jointing to anthesis period (13.1%−31.3%) than anthesis to maturity period (5.7%−10.8%) and sowing to jointing period (8.4%−8.9%). Residual fertilizer N in soil accounted for 24.5%− 38.6% and decreased with increasing total N rate and irrigation. 23.6%− 32.7% of fertilizer N was lost into the environment, and it decreased with increasing irrigation, but wasn’t affected by total N rate. The recovery and residual for topdressing N were higher than those for basal N, whereas loss was lower. Moreover, the loss of basal N mainly occurred before jointing, and the loss of topdressing N mainly occurred from jointing to anthesis and contributed more to total N loss. These results indicated that the current wheat-soil system in Huang-Huai-Hai Plain has substantial potential to coordinate the synchronization of N demand and N supply, and finally reduce N loss. Also, this would provide critical insights to construct general crop N management models for precise N management.

近几十年来，氮肥投入的不断增加，对我国最大的小麦产区黄淮海平原的小麦增产做出了重要贡献。然而，氮肥的利用效率逐渐下降，氮肥用量的增加导致了一系列环境问题。更好地定量了解小麦-土壤系统中水-氮相互作用下基础氮和追施氮的去向对于提高产量和减少环境影响至关重要。我们在两种灌溉方案（降雨、拔节灌溉和开花期灌溉）和三种施氮量（0、180 和 270 kg ^{ha -1}）。结果表明，小麦总氮积累的 54.9%～ 70.4% 来自土壤原生 N，而 29.6%～ 45.1% 来自施肥 N。在节间和花期灌溉对小麦 N 积累的增加更多来自施肥 N 而非土壤原生 N . 与雨养条件相比，灌溉显着提高了孕穗期和开花期的植物NNI。花前 N 易位对籽粒 N 的贡献为 80.6%～ 86.0%，且随全氮用量的增加而增加，但随灌水而减少。随着施氮量和灌溉量的增加，肥料氮回收率增加，拔节至开花期（13.1%-31.3%）的氮回收率高于开花至成熟期（5.7%-10.8%）和播种至拔节期（8.4%） −8.9%）。土壤中施肥 N 占 24.5%− 38。6%，随着全氮用量和灌溉量的增加而降低。23.6%～ 32.7% 的肥料氮流失到环境中，随着灌溉的增加而减少，但不受总氮量的影响。追施氮的回收率和残留量均高于基氮，损失较低。并且，基肥N的损失主要发生在拔节前，追肥N的损失主要发生在拔节至开花期，对总N损失的贡献更大。这些结果表明，目前黄淮海平原小麦-土壤系统具有协调N供需同步，最终减少N损失的巨大潜力。此外，这将为构建用于精确氮管理的通用作物氮管理模型提供重要见解。随灌水量增加而降低，但不受全氮量的影响。追施氮的回收率和残留量均高于基氮，损失较低。并且，基肥N的损失主要发生在拔节前，追肥N的损失主要发生在拔节至开花期，对总N损失的贡献更大。这些结果表明，目前黄淮海平原小麦-土壤系统具有协调N供需同步，最终减少N损失的巨大潜力。此外，这将为构建用于精确氮管理的通用作物氮管理模型提供重要见解。随灌水量增加而降低，但不受全氮量的影响。追施氮的回收率和残留量均高于基氮，损失较低。并且，基肥N的损失主要发生在拔节前，追肥N的损失主要发生在拔节至开花期，对总N损失的贡献更大。这些结果表明，目前黄淮海平原小麦-土壤系统具有协调N供需同步，最终减少N损失的巨大潜力。此外，这将为构建用于精确氮管理的通用作物氮管理模型提供重要见解。并且，基肥N的损失主要发生在拔节前，追肥N的损失主要发生在拔节至开花期，对总N损失的贡献更大。这些结果表明，目前黄淮海平原小麦-土壤系统具有协调N供需同步，最终减少N损失的巨大潜力。此外，这将为构建用于精确氮管理的通用作物氮管理模型提供重要见解。并且，基肥N的损失主要发生在拔节前，追肥N的损失主要发生在拔节至开花期，对总N损失的贡献更大。这些结果表明，目前黄淮海平原小麦-土壤系统具有协调N供需同步，最终减少N损失的巨大潜力。此外，这将为构建用于精确氮管理的通用作物氮管理模型提供重要见解。