Cumulative CO2 emissions (a), relative net N mineralization (b), and net C:N ratio of mineralized SOM pools (c) over the 60-day incubation of the paddy soil under different nutrient addition treatments (see Table 1), i.e., no (CK, the control), low (LN1, LN2, and LN3), and high (HN1, HN2, and HN3) nutrient addition treatments. The net C:N ratio of mineralized SOM was calculated as the ratio of cumulative CO2 emission to net N mineralization at day 60. Values are means ± standard error (n = 3).