Abstract:Denitrification is a microbially facilitated process where nitrate (NO3-) is reduced and ultimately produces dinitrogen(N2) through a series of intermediate nitrogen oxide products, i.e., nitrite, nitric oxide, nitrous oxide. Denitrification has long been considered as one of the major pathways of nitrogen (N) loss when N fertilizer is applied to flooded rice paddies. However, due to the high atmospheric background concentrations of N2, the main denitrification product, and the high spatio-temporal heterogeneity of denitrification, it is difficult to accurately quantify denitrification rates in flooded rice paddies, which hinders the scientific evaluation of N loss from paddies. The selection of appropriate methods for determination of denitrification is the basis for studying denitrification in paddies. In this paper, four approaches developed to measure denitrification in flooded rice paddies were reviewed, i.e., acetylene inhibition technique, 15N tracing method, helium environment-direct N2 quantification, and N2/Ar ratio-membrane inlet mass spectrometry, and the advantages, disadvantages and feasibility of these methods were discussed, and some suggestions were proposed in order to promote the future research of denitrification in paddies.