Experimental warming-driven soil drying reduced N2O emissions from fertilized crop rotations of winter wheat–soybean/fallow, 2009–2014.

Nitrous oxide (N 2 O) emissions from agricultural soils play an important role in the global greenhouse gas budget. However, the response of N 2 O emissions from nitrogen fertilized agricultural soils to climate warming is not yet well understood. A field experiment with simulated warming ( T ) using infrared heaters and its control (C) combined with a nitrogen (N1) fertilization treatment (315 kg N ha −1 y −1 ) and no nitrogen treatment (N0) was conducted over five years at an agricultural research station in the North China Plain in a winter wheat–soybean double cropping system. N 2 O fluxes were measured using static chambers about once every week during July 2009–June 2014. In the N1 treatment, warming decreased the soil moisture and N 2 O emissions in spring, autumn and winter and the annual cumulative emissions. Across all years, N 2 O fluxes were positively correlated with soil temperature and soil moisture. The effect of lower soil moisture on N 2 O fluxes exceeded that of higher temperature, leading to less N 2 O being released by the drier soils under warming. Nitrogen fertilizer increased N 2 O emissions without warming, but did not routinely increase N 2 O emissions under warming treatment. In the N0 treatment, warming neither decreased soil water content nor N 2 O emissions. Temperature and nitrogen input had significant direct and antagonistic effects on cumulative N 2 O flux in the N1 treatment. The decrease in N 2 O emissions from N1 T was due to the significant decrease of soil water content, soil total nitrogen and organic matter, which consequently accelerated N cycle dynamics and advanced wheat growth. [ABSTRACT FROM AUTHOR]