Material and Methods 921 N2O Data Collection

We compiled measurements of direct N2O emission from rice field studies that were published to date in peer-reviewed Chinese and English journals. Data published in Chinese were gathered from the Chinese Journal Net (CJN) full-text database and those in English from the Science Citation Index (SCI) database. Measurements of N2O flux taken from field studies over an abnormally shorter period (Xu et al. 1995), from pot experiments (Xiong et al. 2003a) or from incubation studies (Yan et al. 2000) were not considered in this study. We did not adopt an obviously abnormal result that N2O fluxes were not detectable when pig manure was incorporated at the rate of 164 kg N ha-1 under the water regime of F-D-F (Yang et al. 1996). Measurements from aerobic rice fields (Xu et al. 2004), and from those in which the controlled release fertilizers were applied (Li et al. 2004a) or the amount of organic amendments was not presented for nitrogen treatments (Khalil et al. 1998) were excluded as well.

At the end, we employed 71 field measurements from 17 studies to estimate the emission factor and background emission of N2O during the paddy rice growing season under different water regimes (Tables 9.1, 9.2 and 9.3). These studies were performed at 8 field sites that were located in Beijing, Guangdong, Henan, Jiangsu, Jiangxi, Liaoning, and Sichuan provinces, China over the period of 1992—

Table 9.1 Direct N2O emissions from continuous flooding paddy fields during rice growing season Chemical fertilizer Organic amendment

Location

Year

Typea

Amount kgNha-1

Typeb

Amount kg Nha-1

N2O emission kg Nha"1

Reference

Shenyang,

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