A field experiment was conducted at Pandit Jawaharlal Nehru College of Agriculture and Research Institute, Karaikal during Rabi 2018 to study the nitrogen dynamics in organically cultivated paddy soils of coastal cauvery deltaic region. This study was conducted to evaluate the extent of nitrogen contribution and their dynamics in soil by added organics like green manures (Daincha and sun hemp) and green leaf manures (Pungam and gliricidia) with different levels of vermicompost Viz., 0 t ha-1, 1 t ha-1 and 2 t ha-1. The mineralization pattern of nitrogen is NH4 - N and NO3 - N. During decomposition, before transplanting, after transplanting in early and later stages noted a gradual increase in nitrogen release but steady release observed during mid-stages. In terms of losses, the control registered significantly higher volatilization loss of 1.99 Kg N ha-1 week-1 during second week after transplanting. While the organic treatments registered significantly higher volatilization loss during 13th and 14th week after transplanting. Similarly, the control plot registered significantly higher loss of NO3 - N (2.25 Kg ha-1 week-1) during the 1st week after transplanting and the organic manures showed higher NO3- N loss during 5th to 9th week after transplanting. The total weed removal of nitrogen ranging from 1.8 to 2.6 kg N ha-1. In total, the losses of N from rice soil including crop uptake ranged from 94.6 kg ha-1 in absolute control to 147.2 kg ha-1 in daincha treated plot. As well as, the daincha treated plot resulted a net gain of + 9.6 kg N ha-1 among other green manure / green leaf manure treatments. Among the different vermicompost treatments, application of vermicompost at 2 t ha-1 resulted a net gain of + 4.4 kg N ha-1. From the above observations, it could be concluded that, application of daincha is found to be a suitable green manure for rice crop. Which helps to synchronize and release the nitrogen as per the demand of rice crop.