Optimizing nitrogen fertilizer application with green manure for enhancing nitrogen use efficiency and reducing nitrous oxide (N2O) emission from rice field

Nitrogenous fertilizers may be a key contributor to the emission of nitrous oxide (N2O) from crop field, a greenhouse gases (GHGs) that accelerate climate change, like global warming. However, under field condition impacts of substituting chemical nitrogen (N) fertilizer with green manure on N2O emissions from Indian paddy fields have not been adequately assessed. A two years field experiments were carried out in rice field with randomized block design (RBD) to evaluate of influences of the sole and integrated application of N fertilizers and green manure on crop yield, enhances nitrogen use efficiency (NUE), and effects on N2O emissions. Seven treatments are: F0 (Control, no fertilizer), F1 (N at recommended dose-RD @ 120 kg N ha− 1), F2 (30% reduce N at RD @ 84 kg N ha− 1), F3 (Diammonium phosphate @ 120 kg N ha− 1), F4 (Ammonium sulphate @ 120 kg N ha− 1), F5 (Sesbania aculeate @ 5t ha− 1 + 60 kg N ha− 1) and F6 (Crotalaria juncea @ 5t ha− 1 + 60 kg N ha− 1). The result shows that F5 reduced the cumulative N2O emission by 40.07% and enhanced the NUE and yield, by 24.59% and 22.22%, respectively, as compared with F1. Significant negative correlation between NUE parameters and N2O emissions were found throughout the rice growing season. The findings suggest that incorporating Sesbania aculeata with 50% reduction in fertilizer rate (60 kg N ha–1) compared to the recommended rate (@120 kg N ha–1) regarded as effective and efficient fertilizer management practice to mitigate climate change by minimizing GHGs emission like N2O emissions, while simultaneously ensure crop productivity.