Measurement of N2O emissions over the whole year is necessary for estimating reliable emission factors

Ziyin Shang* (Corresponding Author), Mohamed Abdalla, Matthias Kuhnert, Fabrizio Albanito, Feng Zhou, Longlong Xia, Pete Smith

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Nitrous oxide emission factors (N2O-EF, percentage of N2O–N emissions arising from applied fertilizer N) for cropland emission inventories can vary with agricultural management, soil properties and climate conditions. Establishing a regionally-specific EF usually requires the measurement of a whole year of N2O emissions, whereas most studies measure N2O emissions only during the crop growing season, neglecting emissions during non-growing periods. However, the difference in N2O-EF (ΔEF) estimated using measurements over a whole year (EFwy) and those based on measurement only during the crop-growing season (EFgs) has received little attention. Here, we selected 21 studies including both the whole-year and growing-season N2O emissions under control and fertilizer treatments, to obtain 123 ΔEFs from various agroecosystems globally. Using these data, we conducted a meta-analysis of the ΔEFs by bootstrapping resampling to assess the magnitude of differences in response to management-related and environmental factors. The results revealed that, as expected, the EFwy was significantly greater than the EFgs for most crop types. Vegetables showed the largest ΔEF (0.19%) among all crops (0.07%), followed by paddy rice (0.11%). A higher ΔEF was also identified in areas with rainfall ≥600 mm yr−1, soil with organic carbon ≥1.3% and acidic soils. Moreover, fertilizer type, residue management, irrigation regime and duration of the non-growing season were other crucial factors controlling the magnitude of the ΔEFs. We also found that neglecting emissions from the non-growing season may underestimate the N2O-EF by 30% for paddy fields, almost three times that for non-vegetable upland crops. This study highlights the importance of the inclusion of the non-growing season in the measurements of N2O fluxes, the compilation of national inventories and the design of mitigation strategies.
Original languageEnglish
Article number113864
Pages (from-to)113864
Number of pages8
JournalEnvironmental Pollution
Volume259
Early online date20 Dec 2019
DOIs
Publication statusPublished - Apr 2020

Keywords

  • nitrous oxide
  • greenhouse gas
  • fallow
  • residual fertilizer N
  • nitrogen use efficiency
  • Residual fertilizer N
  • Nitrogen use efficiency
  • Greenhouse gas
  • Nitrous oxide
  • Fallow
  • MANAGEMENT
  • DENITRIFICATION
  • RICE PADDY
  • NITROUS-OXIDE EMISSIONS
  • FERTILIZER
  • AGRICULTURAL SOILS
  • DYNAMICS
  • CLIMATE MITIGATION
  • CROP PRODUCTIVITY
  • PADDY FIELDS

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