Impact of ozone pollution on nitrogen fertilization management during maize (Zea mays L.) production

The impacts of ozone (O-3) on crops have been extensively studied and are well understood. However, little information is available on the response of crops (especially maize) to the interactive effects of O-3 and nitrogen (N) fertilizer. To this end, a maize cultivar (Zheng dan 958, ZD958) that is common in China was exposed to two O-3 treatments and four N levels. We found that (1) the interactions between O-3 and N were non-significant for grain yield, plant biomass, C and N, although N addition significantly increased all parameters except C concentrations in grain and plant; (2) compared to NF (non-filtered ambient air O-3 concentration), NF60 (NF plus an extra 60 ppb O-3) increased the optimum N application rates (Nopt) in grain yield and plant biomass, but not grain yield and plant biomass potentials, thus resulting in lower N use efficiencies (NUE) and a larger risk of N-related environmental pollution (e.g., increased N2O emission) under N opt in NF60; (3) because of higher optimum plant N uptake (PN opt ) in NF60, relative to NF, plant N-saturated conditions for grain yield potential can be gradually turned into Nlimited conditions as O-3 pollution increases. These findings manifest that O-3 is a vital global change factor impacting the management of N fertilization. If current O-3 pollution is substantially reduced, maize yield and biomass potentials can be increased under reductions in N input and N-related environmental pollution. In addition, these results can also contribute in developing and verifying N opt model considering O-3 pollution in the future. (C) 2020 Elsevier Ltd. All rights reserved.