Producing more grain yield of rice with less ammonia volatilization and greenhouse gases emission using...

Ammonia (NH₃) volatilization and greenhouse gas (GHG) emission from rice (Oryza sativa L.) fields contaminate the atmospheric environment and lead to global warming. Field trials (2013-2015) were conducted to estimate the influences of different types of fertilization practices on grain yield, NH₃ volatilization, and methane (CH₄) and nitrous oxide (N₂O) emissions in a double rice cropping system in Central China. Results showed that grain yields of rice were improved significantly by using slow/controlled-release urea (S/C-RU). Compared with farmers' fertilizer practice (FFP) treatment, average annual grain yield with application of polymer-coated urea (CRU), nitrapyrin-treated urea (CP), and urea with effective microorganism (EM) treatments was increased by 18.0%, 16.2%, and 15.4%, respectively. However, the effects on NH₃ volatilization and CH₄ and N₂O emissions differed in diverse S/C-RU. Compared with that of the FFP treatment, the annual NH₃ volatilization, CH₄ emission, and N₂O emissions of the CRU treatment were decreased by 64.8%, 19.7%, and 35.2%, respectively; the annual CH₄ and N₂O emissions of the CP treatment were reduced by 33.7% and 40.3%, respectively, while the NH₃ volatilization was increased by 18.5%; the annual NH₃ and N₂O emissions of the EM treatment were reduced by 6.3% and 28.7%, while the CH₄ emission was improved by 4.3%. Overall, CP showed the best emission reduction with a decrement of 34.3% in global warming potential (GWP) and 44.4% in the greenhouse gas intensity (GHGI), followed by CRU treatment with a decrement of 21.1% in GWP and 31.7% in GHGI, compared with that of the FFP treatment. Hence, it is suggested that polymer-coated urea can be a feasible way of mitigating NH₃ volatilization and CH₄ and N₂O emission from rice fields while maintaining or increasing the grain yield in Chinese, the double rice cropping system.