Effect of nano urea on greenhouse gas emissions in transplanted rice (Oryza sativa L.) ecosystems

The application of conventional nitrogen fertilizer (urea) to improve rice crop yield has a significant influence on soil methane (CH4) and nitrous oxide (N2O) emissions. An experiment was conducted at Tamil Nadu Agricultural University, Coimbatore, wetlands farm, during the summer of 2023. A Randomized Block Design (RBD) was used with 8 treatments and 3 replications to evaluate the impact of different nitrogen application strategies on greenhouse gas emissions, specifically methane and nitrous oxide in transplanted rice, including the varying nitrogen levels. The study aimed to improve rice growth and yield through foliar application of nano urea, focusing on the rice variety CO55 with a recommended dose of NPK (150:50:50 NPK kg/ha). The results indicated that applying 75 kg nitrogen/ha (50% of the recommended dose) as basal through conventional urea, along with 3 nano urea foliar sprays at 20, 40 and 60 days after transplanting (T-5), resulted in significantly lower methane and nitrous oxide emissions compared with 100% of the recommended nitrogen dose i.e. 150 kg nitrogen/ha applied through conventional urea, with 25% used at basal, active tillering, panicle initiation and heading stage (T-1) and 150 kg nitrogen/ha i.e. 100% recommended dose of nitrogen applied through conventional urea, with 50% as basal and 2 top dressings of 25% of the recommended dose of nitrogen (RDN) each at active tillering and panicle initiation (T-2).