Warming increase the N2O emissions from wheat fields but reduce the wheat yield in a rice-wheat rotation system

Abstract

Global warming often affects the greenhouse gas (GHG) emissions, yet the effect of simulated warming on GHG emissions from wheat fields, the major source of nitrous oxide (N2O) emissions, is still unclear. Therefore, using a free-air temperature increase system, we conducted a two-year field experiment to explore the effects of simulated warming on N2O and methane (CH4) emissions as well as wheat yields in a rice-wheat rotation system. Our results showed that compared with the ambient control, warming increased the cumulative seasonal emissions of N2O by 34.21 % (P < 0.05), but did not affect the seasonal CH4 emissions in the two years. Soil C/N ratio, pH, nirK gene and (nirK+nirS)/nosZ ratio were the main causes affecting N2O emissions. Warming reduced the wheat yield by 19.42 % mainly due to the reduction of panicles and shorter vegetative growth (P < 0.05). Greenhouse gas intensity of warming treatment was 10.42 % higher than that of the ambient control. Our findings indicate that warming may reduce the wheat yield but increase N2O emissions in China’s wheat-rice rotation system and emphasize the need for agronomic practices of high wheat yields and low GHG emissions in the climate change world.