Foliar <scp>N<sub>2</sub>O</scp> emissions constitute a significant source to atmosphere
Shuping Qin, Yaxing Pang, Huixian Hu, Ting Liu, Dan Yuan, Timothy J. Clough, Nicole Wrage‐Mönnig, Jiafa Luo, Shungui Zhou, Lin Ma, Chunsheng Hu, O. Oenema
Abstract
Abstract Nitrous oxide (N 2 O) is a potent greenhouse gas and causes stratospheric ozone depletion. While the emissions of N 2 O from soil are widely recognized, recent research has shown that terrestrial plants may also emit N 2 O from their leaves under controlled laboratory conditions. However, it is unclear whether foliar N 2 O emissions are universal across varying plant taxa, what the global significance of foliar N 2 O emissions is, and how the foliage produces N 2 O in situ. Here we investigated the abilities of 25 common plant taxa, including trees, shrubs and herbs, to emit N 2 O under in situ conditions. Using 15 N isotopic labeling, we demonstrated that the foliage‐emitted N 2 O was predominantly derived from nitrate. Moreover, by selectively injecting biocide in conjunction with the isolating and back‐inoculating of endophytes, we demonstrated that the foliar N 2 O emissions were driven by endophytic bacteria. The seasonal N 2 O emission rates ranged from 3.2 to 9.2 ng N 2 O–N g −1 dried foliage h −1 . Extrapolating these emission rates to global foliar biomass and plant N uptake, we estimated global foliar N 2 O emission to be 1.21 and 1.01 Tg N 2 O–N year −1 , respectively. These estimates account for 6%–7% of the current global annual N 2 O emission of 17 Tg N 2 O–N year −1 , indicating that in situ foliar N 2 O emission is a universal process for terrestrial plants and contributes significantly to the global N 2 O inventory. This finding highlights the importance of measuring foliar N 2 O emissions in future studies to enable the accurate assigning of mechanisms and the development of effective mitigation.