title: Disaggregated N2O emission factors in China based on cropping parameters create a robust approach to the IPCC Tier 2 methodology.
abstract: China accounts for a third of global nitrogen fertilizer consumption. Under an International Panel on Climate Change (IPCC) Tier 2 assessment, emission factors (EFs) are developed for the major crop types using country-specific data. IPCC advises a separate calculation for the direct nitrous oxide (N2O) emissions of rice cultivation from that of cropland and the consideration of the water regime used for irrigation. In this paper we combine these requirements in two independent analyses, using different data quality acceptance thresholds, to determine the influential parameters on emissions with which to disaggregate and create N2O EFs. Across China, the N2O EF for lowland horticulture was slightly higher (between 0.74% and 1.26% of fertilizer applied) than that for upland crops (values ranging between 0.40% and 1.54%), and significantly higher than for rice (values ranging between 0.29% and 0.66% on temporarily drained soils, and between 0.15% and 0.37% on un-drained soils). Higher EFs for rice were associated with longer periods of drained soil and the use of compound fertilizer; lower emissions were associated with the use of urea or acid soils. Higher EFs for upland crops were associated with clay soil, compound fertilizer or maize crops; lower EFs were associated with sandy soil and the use of urea. Variation in emissions for lowland vegetable crops was closely associated with crop type. The two independent analyses in this study produced consistent disaggregated N2O EFs for rice and mixed crops, showing that the use of influential cropping parameters can produce robust EFs for China.
authors: Sustainable Soil & Grassland Systems, Rothamsted Research, North Wyke, Devon, EX20 1NJ, UK.
authors: Anita
authors: A
authors: Shepherd
authors: Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
authors: Xiaoyuan
authors: X
authors: Yan
authors: Institute of Biological and Environmental Sciences, University of Aberdeen, 23 St Machar Drive, Aberdeen, AB24 3UU, UK.
authors: Dali
authors: D
authors: Nayak
authors: Animal Science, Edward Llwyd Building, Penglais Campus, Aberystwyth, Ceredigion, SY23 3FL, UK.
authors: Jamie
authors: J
authors: Newbold
authors: Land Economy & Environment Research, SRUC, Nicholas Kemmer Road, Edinburgh, EH9 3FH, UK.
authors: Dominic
authors: D
authors: Moran
authors: Sustainable Soil & Grassland Systems, Rothamsted Research, North Wyke, Devon, EX20 1NJ, UK.
authors: Mewa Singh
authors: MS
authors: Dhanoa
authors: Sustainable Soil & Grassland Systems, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, UK.
authors: Keith
authors: K
authors: Goulding
authors: Institute of Biological and Environmental Sciences, University of Aberdeen, 23 St Machar Drive, Aberdeen, AB24 3UU, UK.
authors: Pete
authors: P
authors: Smith
authors: Sustainable Soil & Grassland Systems, Rothamsted Research, North Wyke, Devon, EX20 1NJ, UK.
authors: Laura M
authors: LM
authors: Cardenas
keywords: Agriculture; China; Emission factor; Fertilizer; Greenhouse gas; Nitrous oxide