Despite several implications of excessive nitrogen (N) use on environment, information on effect of elevated carbon dioxide (CO₂) and/or temperature on recovery and use efficiency of applied N are limited. Hence, this field study was carried out for three consecutive seasons of wheat crop during 2016−17 to 2018−19 in Open Top Field chambers (OTCs) under four climate conditions, viz. ambient, elevated CO₂ (∼550 μmol mol⁻¹), elevated temperature (∼ 2.0 °C above ambient) and co-elevation of both CO₂ and temperature. Interaction of climate and year was found non-significant (P > 0.05) for the studied parameters, but, significant effect of climate was observed in most of the parameters except straw N uptake. Pooled data analysis of three consecutive crop years indicated CO₂ elevation significantly enhancing above ground biomass and grain yield and also N uptake in grain. The CO₂ mediated grain yield response was to the extent of 15% (P < 0.0001) as compared to ambient, however, the yield advantage was partly offset with co-elevation of temperature. Elevation in CO₂ produced 16% higher total N uptake than ambient. Co-elevation of CO₂ and temperature showed a higher N uptake by about 10% as compared to ambient. In absolute terms, 25 and 15 kg ha⁻¹ of additional N uptake was observed under elevation of CO₂, and with co-elevation of temperature, respectively. Agronomic (AE_N) and physiological N use efficiency (PE_N), recovery of applied fertilizer N (RE_N) and partial factor productivity (PFP_N) were significantly higher under CO₂ elevation. Co-elevation of temperature caused significant depletion in RE_N and PFP_N compared to CO₂ elevation. The three years’ study clearly indicated significant advantage in yield and recovery of applied fertilizer N with CO₂ elevation, at the cost of significantly higher N uptake. Significantly higher N removal and trend of declining soil mineral N content under elevated CO₂ indicates possible N mining and N limitations may constrain the long-term plant response to CO₂ elevation. The study has significance in N management for sustaining productivity and maintaining soil nutrient pool under changing climate.

尽管过量使用氮对环境有若干影响，但有关升高的二氧化碳（CO ₂）和/或温度对所施用氮的回收率和使用效率的影响的信息仍然有限。因此，本田间研究是在四种气候条件下，在开放式田间室（OTC）中于2016-17至2018-19连续三个季节进行的小麦作物的研究。环境，升高的CO ₂（〜550μmolmol ^-1），升高的温度（高于环境〜2.0 °C）和两种CO _2的共升高和温度。对于所研究的参数而言，气候和年份之间的相互作用没有显着意义（P> 0.05），但是，除秸秆吸收氮外，在大多数参数中都观察到了气候的显着影响。连续三个作物年度的汇总数据分析表明，CO ₂升高显着提高了地上生物量和谷物产量，并增加了谷物的氮吸收量。与环境相比，CO ₂介导的谷物产量响应达到了15％的程度（P <0.0001），但是，产量的优势被温度的共同升高部分抵消了。CO _2的升高产生的总氮吸收量比周围环境高16％。CO ₂共举与温度相比，温度显示出更高的N吸收率，约为10％。绝对而言，在CO ₂升高和温度升高的情况下，分别增加了25和15 kg ha ^-1的氮吸收。在CO ₂升高的情况下，农艺（AE _N）和生理氮素利用效率（PE _N），施肥氮（RE _N）的回收率和部分生产力（PFP _N）显着更高。与CO ₂相比，温度的共同升高导致RE _N和PFP _N显着耗尽海拔。三年的研究清楚地表明，随着CO ₂含量的升高，施用的肥料N的产量和回收率均显着提高，但氮吸收量显着增加。在较高的CO ₂浓度下，较高的氮去除率和土壤矿质氮含量的下降趋势表明可能存在氮的开采和氮的限制可能会限制植物对CO ₂浓度升高的长期反应。该研究对于气候变化下维持生产力和维持土壤养分库的氮管理具有重要意义。