Comparing a process-based agro-ecosystem model to the IPCC methodology for developing a national inventory of N2O emissions from arable lands in China

Authors

Changsheng Li, University of New Hampshire - Main CampusFollow
Yahui Zhuang, Chinese Academy of Sciences
Meiqio Cao, Chinese Academy of Sciences
Zhaohua Dai, Chinese Academy of Sciences
P Crill, Stockholm University
Steve Frolking, University of New Hampshire - Main CampusFollow
B Moore, University of New Hampshire - Main CampusFollow
William A. Salas, University of New Hampshire - Main Campus
Wenzhi Song, Chinese Academy of Sciences
Xiaoke Wang, Chinese Academy of Sciences

Abstract

Nations are now obligated to assess their greenhouse gas emissions under the protocols of Article 4 of the United Nations Framework Convention on Climate Change. The IPCC has developed `spreadsheet-format' methodologies for countries to estimate national greenhouse gas emissions by economic sector. Each activity has a magnitude and emission rate and their product is summed over all included activities to generate a national total (IPCC, 1997). For N₂O emissions from cropland soils, field studies have shown that there are important factors that influence N₂O emissions at specific field sites that are not considered in the IPCC methodology. We used DNDC, a process-oriented agroecosystem model, to develop an unofficial national inventory of direct N₂O emissions from cropland in China. We assembled county-scale data on soil properties, daily weather, crop areas, N-fertilizer use, livestock populations (for manure inputs to cropland), and agricultural management for the 2500 counties in mainland China. Total 1990 cropland area was 0.95 million km². Total N-fertilizer use in China in 1990 was 16.6 Tg N. The average fertilization rate was 175 kg N ha⁻¹ cropland. One-year simulations with DNDC were run for each crop type in each county to generate estimates of direct N₂O emissions from soils. National totals were the sum of results for all crop simulations across all counties. Baseline simulations estimated that total N₂O emission from arable land in China in 1990 was 0.31 Tg N₂O-N yr⁻¹. We also ran simulations with zero N-fertilizer input; the difference between the zero-fertilizer and the baseline run is an estimate of fertilizer-induced N₂O emissions. The fertilizer-induced emission was 0.13 Tg N₂O-N yr⁻¹, about 0.8% of total N-fertilizer use (lower than the mean but within the IPCC range of 1.25±1.0%). We compared these results to our estimates of county-scale IPCC methodology emissions. Total emissions were similar but geographical patterns were quite different.

Department

Earth Sciences, Earth Systems Research Center

Publication Date

7-2001

Journal Title

Nutrient Cycling in Agroecosystems

Publisher

Springer

Digital Object Identifier (DOI)

10.1023/A:1012642201910

Document Type

Article

Recommended Citation

C. Li et al., Nutrient Cycling in Agroecosystems, vol. 60, no. 1/3, pp. 159–175, 2001.

Rights

© 2001 Kluwer Academic Publishers.