Estimating nitrous oxide emission flux from arable lands in China using improved background emission and fertilizer-induced emission factors

A nitrous oxide (N2O) emission database was compiled for arable land (284 measurements from 62 studies) to establish predictive models for building a greenhouse gas emission inventory in China. Arable lands were grouped into dry land and rice paddy based on the IPCC 2006 guidelines. The results of the meta analysis show that the annual mean N2O fluxes from dry land and rice paddy were 4.69 +/- 4.62 (SD) and 5.89 +/- 3.23 kg N2O-N ha(-1) yr(-1). Fertilizer-induced N2O emission factors were 0.68 +/- 0.41% for dry land, and 0.49 +/- 0.43% for rice paddy. The relationship between N2O flux from arable lands and various environmental variables were analyzed, and the magnitude of N2O emissions from zero mineral N addition control plots (background emission) was determined based on precipitation. Based on the above background emissions and correlation coefficients, two new predictive models were established to estimate N2O emissions from arable lands in China. Comparison showed that the precipitation-rectified background emissions could largely improve the model predictions, and the two new models had better performance than the 1996 IPCC guideline method. Therefore, it is strongly recommended that the important local environmental variables be included in the estimates when compiling a national N2O emission inventory.