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Aims: N2O emitted by agricultural ecosystems has a great impact on global warming and climate change. The use of controlled-release fertilizers (CRF) can decrease greenhouse gas emissions. However, the general patterns and variability of nitrogen functional genes in response to CRF associated with N2O emission have not been synthesized under climate change. Methods: We investigated the effects of CRF, elevated CO2 concentration (EC), elevated temperature (ET), and their combination on N2O emission, enzyme activities and gene abundances. Results: We found that the cumulative N2O emissions was in the range of 0.39–1.65 kg·ha−1 in the wheat-growing season, accounting for 0.54%–2.29% of the total nitrogen input. N2O emissions were considerably positively correlated with ammonia-oxidizing bacteria (AOB) at elongation stage. CRF inputs significantly decreased N2O emissions by 29 − 66% compared with urea due to decreased AOB abundance and inhibited nitrite reductase activities at elongation stage. EC significantly decreased N2O emissions by 30 − 50% likely resulting from the inhibition in nitrifying and denitrifying community compared with ambient CO2 concentration. ET significantly increased N2O emissions by increasing N mineralization in wheat soil under CRF due to higher NH4+-N and NO3−-N concentration in wheat soil at elongation stage. In addition, ECET had antagonistic effect on N2O emissions. CRF had no significant effect on wheat yield under climate change scenarios. Conclusions: CRF decreased the cumulative N2O emissions under climate change scenarios. This is critical for understanding the responses of N2O emissions from wheat soil under CRF to future CO2 enrichment and warming for the establishment of mitigation and adaptation policies. [ABSTRACT FROM AUTHOR]

To investigate the effects of nitrification inhibitors applied in the wheat season on the soil inorganic nitrogen (N), N2O emissions and related enzyme activities in the soybean season for the wheat-soybean rotation system under the background of climate change, different atmospheric CO2 concentration (400 and 600 µmol/mol) and air temperature (ambient temperature T and T+2 °C) were set in the control air chamber. The contents of soybean soil nitrate and ammonium N, nitrification and denitrification-related enzyme activities and N2O emissions were measured when nitrification inhibitors were added in the wheat season. The results showed that the addition of nitrification inhibitor combined with wheat straw returning to the field in wheat season increased soil nitrate N and ammonium N in soybean season, whereas it had little effect on the enzyme activities of soil nitrification-denitrification. Elevated air temperature (ET) significantly increased the content of nitrate N in soybean soil, while the content of ammonium N significantly decreased. At the conditions of increased atmospheric CO2 concentration (EC) or simultaneously increased air temperature and CO2 concentration (ECT), soil nitrate N and ammonium N content both increased, whereas there were no significantly difference with the inorganic N content under ambient temperature and CO2 concentration (CK). The enzyme activities of soil nitrification-denitrification under different environmental conditions showed no obvious regularity. Under ET and ECT conditions, the total amount of N2O emission in soybean growing season was significantly higher than that in CK treatment, and the addition of nitrification inhibitors reduced N2O emission. The difference of N2O emissions between EC and CK conditions was small, whereas the N2O emission of nitrification inhibitor treatment was significantly higher than that of common urea treatment under CK condition. To sum up, under the background of rising air temperature and CO2 concentration in the future, reasonable application of nitrification inhibitors is beneficial to the increase of available N in soybean soil, whereas the increase of air temperature (ET and ECT) may increase N2O emissions, and adding nitrification inhibitors can reduce N2O emissions. The changes in N2O emissions are not obvious when the CO2 concentration (EC) increased alone. This study can provide a theoretical support for fertilization management and farmland N2O emission reduction under the wheat- soybean crop rotation system under the background of future climate change. [ABSTRACT FROM AUTHOR]

• APSIM predicted the growing period, leaf area index, biomass, and yield well. • Elevated [CO 2 ] alleviated the negative effects of warming on wheat yield. • Increased temperature and elevated [CO 2 ] mainly affected the wheat grain number. • Extreme high temperature notably affected the yield of later-maturing cultivar. • The early-maturing wheat cultivar would be better adapted to climate change. Understanding the impacts of rising temperature and elevated [CO 2 ] on different crop cultivars is critical to devising agronomic strategies and cultivar selection in the context of climate change adaptation. The growth period, biomass, and yield of two wheat cultivars (early– vs. late–maturing) were simulated by the Agricultural Production Systems sIMulator (APSIM) validated with pot experiments under the scenarios of elevated [CO 2 ] and 2 °C warming based on the baseline climate for 1961–2016 at Taigu in North China. We also investigated the effects of extreme high temperature on the yield and yield components of these wheat cultivars. We found that APSIM well simulated the changes in the growth period, leaf area index (LAI), biomass, and yield induced by 2 °C warming and elevated [CO 2 ]. Long–term simulations showed that 2 °C warming decreased the growing period between sowing and jointing for both cultivars. 2 °C warming and elevated [CO 2 ] affected the wheat yield mainly by altering the grain numbers. Extreme high temperature decreased the grain numbers and yield of the late–maturing cultivar but not the early–maturing one. The findings suggest that early–maturing cultivar would be better adapted to elevated [CO 2 ] and rising temperature than the late–maturing one in the eastern Loess Plateau. [ABSTRACT FROM AUTHOR]