Improving nitrogen (N) use efficiency is urgently needed to achieve co-sustainability of agricultural productivity and environmental quality. Environmental conditions and farming management practices affect the N cycle in agroecosystems. Particularly, weather conditions during the pre-growing-season (e.g. winter and early spring for the U.S. Corn Belt) can influence the dynamics of soil inorganic N (SIN) content and have implications for the end-of-season crop yield. Here, we used an advanced agroecosystem model, ecosys, to assess the consequences of different pre-growing-season weather scenarios in terms of both SIN dynamics and crop productivity. We first benchmarked ecosys using extensive N trial data collected across the U.S. Midwest, and found that ecosys captured the N fertilizer-yield responses and field-scale N cycle dynamics. We then used ecosys to conduct multiple experiments by changing the pre-growing-season precipitation and temperature, and assessed how these changes affected soil N dynamics and crop yield. We found that: (1) wetter pre-growing-seasons reduced SIN content through increasing leaching, leading to a reduction in corn grain yield of 0.54–0.86 Mg/ha (5–14%) under no fertilizer and of 0.21–0.33 Mg/ha (1–3%) under the normal N fertilizer rate (167 kg N/ha; Illinois average N fertilizer rate in 2018); yield loss induced by higher pre-growing-season precipitation can be eliminated by applying more N fertilizer in spring; and (2) colder pre-growing-seasons can reduce SIN content through decreased N mineralization and enhanced leaching. Both factors further contribute to corn yield loss of 0.10–0.68 Mg/ha (2–8%) under no fertilizer and of 0.12–0.48 Mg/ha (1–4%) under the normal fertilizer rate; however, in this case adding more fertilizer does not necessarily eliminate the yield loss caused by the colder pre-growing-season, because the lower temperature not only causes SIN deficiency but also reduces early-growing-season active root nutrients uptake and crop N demand by cooling soil temperature. These findings expand our understanding of the impact of weather conditions on crop yield and can inform improvements in N fertilizer use efficiency in the U.S. Midwest agroecosystems.

迫切需要提高氮 (N) 的利用效率，以实现农业生产力和环境质量的共同可持续性。环境条件和农业管理实践影响农业生态系统中的氮循环。特别是，生长前季节的天气条件（例如美国玉米带的冬季和早春）会影响土壤无机氮（SIN）含量的动态，并对季末作物产量产生影响。在这里，我们使用先进的农业生态系统模型ecosys来评估不同生长季节前天气情景在 SIN 动态和作物生产力方面的后果。我们首先使用在美国中西部收集的大量 N 试验数据对ecosys进行了基准测试，发现ecosys捕获了氮肥产量响应和田间规模的氮循环动态。然后我们使用ecosys通过改变生长季前的降水和温度进行多项实验，并评估这些变化如何影响土壤氮动态和作物产量。我们发现：(1) 生长前较湿润的季节通过增加浸出降低了 SIN 含量，导致玉米籽粒产量在不施肥和 0.21-0.33 Mg 的情况下减少 0.54-0.86 Mg/ha (5-14%) /ha（1-3%）低于正常氮肥用量（167 kg N/ha；伊利诺伊州 2018 年平均氮肥用量）；春季多施氮肥可消除因生长季前降水量增加而造成的产量损失；(2) 较冷的生长前季节可以通过减少 N 矿化和增强浸出来降低 SIN 含量。这两个因素进一步导致玉米产量损失 0.10-0.68 毫克/公顷 (2-8%) 在不施肥和 0.12-0 的情况下。48 Mg/ha (1–4%) 在正常施肥量下；然而，在这种情况下，添加更多的肥料并不一定能消除由较冷的生长期造成的产量损失，因为较低的温度不仅会导致 SIN 缺乏，而且会降低生长期的活性根系养分吸收和作物对氮的需求通过冷却土壤温度。这些发现扩大了我们对天气条件对作物产量影响的理解，并可以为美国中西部农业生态系统中氮肥使用效率的提高提供信息。因为较低的温度不仅会导致 SIN 缺乏，而且还会通过降低土壤温度来减少早期生长季节的活性根系养分吸收和作物对氮的需求。这些发现扩大了我们对天气条件对作物产量影响的理解，并可以为美国中西部农业生态系统中氮肥使用效率的提高提供信息。因为较低的温度不仅会导致 SIN 缺乏，而且还会通过降低土壤温度来降低早期生长季节的活性根系养分吸收和作物对氮的需求。这些发现扩大了我们对天气条件对作物产量影响的理解，并可以为美国中西部农业生态系统中氮肥使用效率的提高提供信息。