Weakened growth of cropland N2O emissions in China associated with nationwide policy interventions

Ziyin Shang, Feng Zhou*, Pete Smith, Eri Saikawa, Philippe Ciais, Jinfeng Chang, Hanqin Tian, Stephen Del Grosso, Akihiko Ito, Minpeng Chen, Qihui Wang, Yan Bo, Xiaoqing Cui, S Castaldi, Radoslaw Juszczak, Asa Kasimir, Vincenzo Magliulo, Sergiy Medinets, Volodymyr Medinets, RM ReesGeorg Wohlfahrt, Simone Sebbatini

*Corresponding author for this work

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Abstract

China has experienced rapid agricultural development over recent decades, accompanied by increased fertilizer consumption in croplands, but the trend and drivers of the associated nitrous oxide (N2O) emissions remain uncertain. The primary sources of this uncertainty are the coarse spatial aggregation of agricultural activity data and the incomplete model representation of N2O emissions in response to management. Here we provide new data-driven estimates of cropland N2O emissions across China from 1990 to 2014, complied using a global monitoring network, nationwide survey-based reconstruction of N-fertilization and irrigation, and an updated version of spatially-referenced nonlinear algorithm. In addition, we have evaluated the drivers behind changing cropland N2O patterns using an index decomposition analysis approach. We find that China’s annual cropland-N2O emissions increased on average by +11.2 Gg N yr2 (P < 0.001) from 1990 to 2003, after that, coincident with an ensemble of process-based land-surface models (LSMs), emissions have plateaued until 2014 (+2.8 Gg N yr2, P = 0.02). The slowdown after 2003 was pervasive across the majority of croplands accounting in total for ~2/3 of the total cropland areas. This change was mainly driven by the nationwide improvement (reduction) of N-fertilizer application rates, partially due to the prevalence of the Nationwide Soil Testing and Formulation Fertilization Program launched in the early 2000s. This reduction has almost offset the policy-driven cropland expansion across most regions, but particularly in the Northeast Plain and the lower Yangtze Basin. Our results underline the importance of high-resolution activity data and of spatially-explicit responses of N2O emission to management for capturing cropland-N2O emission patterns. Improving the representation of nationwide policy intervention in LSMs is also recommended for future projections.
Original languageEnglish
Pages (from-to)3706-3719
Number of pages14
JournalGlobal Change Biology
Volume25
Issue number11
Early online date24 Jun 2019
DOIs
Publication statusPrint publication - Nov 2019

Keywords

  • Nitrous oxide
  • Agricultural soils
  • Emission
  • Flux upscaling
  • Agricultural management
  • Process-based model
  • Temporal trend
  • Spatial pattern

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    Shang, Z., Zhou, F., Smith, P., Saikawa, E., Ciais, P., Chang, J., Tian, H., Del Grosso, S., Ito, A., Chen, M., Wang, Q., Bo, Y., Cui, X., Castaldi, S., Juszczak, R., Kasimir, A., Magliulo, V., Medinets, S., Medinets, V., ... Sebbatini, S. (2019). Weakened growth of cropland N2O emissions in China associated with nationwide policy interventions. Global Change Biology, 25(11), 3706-3719. https://doi.org/10.1111/gcb.14741