Global N2O emissions from cropland driven by environmental factors and nitrogen addition: comparison and uncertainty analysis

Authors: XU, RONGTING - Auburn University; TIAN, HANQIN - Auburn University; PAN, SHUFEN - Auburn University; Prior, Stephen - Steve; FENG, YUCHENG - Auburn University; DANGAL, SHREE - Woods Hole Research Center

Submitted to: Global Biogeochemical Cycles
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2020
Publication Date: 11/24/2020
Citation: Xu, R., Tian, H., Pan, S., Prior, S.A., Feng, Y., Dangal, S. 2020. Global N2O emissions from cropland driven by environmental factors and nitrogen addition: comparison and uncertainty analysis. Global Biogeochemical Cycles. 34:e2020GB006698. https://doi.org/10.1029/2020GB006698.
DOI: https://doi.org/10.1029/2020GB006698

Interpretive Summary: This effort describes the use of a Dynamic Land Ecosystem Model (DLEM) to characterized global N2O emissions from cropland driven by multiple environmental factors and management strategies during 1961-2010. Estimates suggest that global cropland N2O emissions increased by 180% during 1961-2014 (1.1 to 3.3 Tg N yr-1). Synthetic N fertilizer was responsible for ~70% of total emissions during 2000-2014. At regional scales, Europe and North America were leading regions for N2O emissions in the 1960s, but East Asia took the lead after the 1990s. This study considered various N input sources and environmental factors to provide time series estimates of N2O emissions. Such information could help develop future N2O mitigation strategies by countries with higher emission rates.

Technical Abstract: Human activities have caused significant perturbations of the nitrogen (N) cycle, resulting in an ~21% increase in atmospheric N2O concentration since the pre-industrial era. Substantial efforts have been made to quantify global and regional N2O emissions from cropland soils in the last three decades using a wide variety of approaches and the estimates remain largely uncertain. Moreover, how annual and decadal climate changes and variability affected N2O emissions from cropland is unknown. Herein, we applied a process-based Dynamic Land Ecosystem Model (DLEM) to estimate global N2O emissions from cropland driven by multiple environmental factors and management strategies. We estimate that global cropland N2O emissions increased by 180% (from 1.1±0.2 to 3.3±0.1 Tg N yr-1) during 1961-2014. Synthetic N fertilizer applications accounted for ~70% of total emissions during 2000-2014. At the regional scale, Europe and North America were two leading regions for N2O emissions in the 1960s. However, East Asia became the largest emitter after the 1990s. Compared with estimates based on linear and nonlinear emission factors, our results were 150% and 186% higher, respectively, at the global scale during 2000-2014. This study considered various N input sources and environmental factors to provide a time series estimate of N2O emissions. This information could prompt future N2O mitigation strategies by countries with higher emission rates.