Hoang Thi Thai Hoa1, Do Dinh Thuc1, Trinh Thi Sen1, Tran Thi Xuan Phuong1
1 Hue University – Hue College of Agriculture and Forestry, 102 Phung Hung street, Hue city, Thua Thien Hue province, Vietnam, 530000, http://www.huaf.edu.vn, firstname.lastname@example.org
Wetland rice is the largest source of CH4 emission from cropping and also offers the most options to modify crop management for reducing these emissions. The experiment was conducted in two rice cropping systems in 2014 and 2015 to assess the influence of rates and types of nitrogen fertilizer on CH4 emission in rice fields of Central Vietnam. Results show that high fertilizer N rates (120 kg N ha−1) increased seasonal cumulative CH4 emissions from 11.6 – 26.7 g m-2 for urea and 6.7 – 19.5 g m-2 for ammonium chloride in winter spring and summer cropping seasons relative to when no N fertilizer was applied. Replacing urea with ammonium chloride at the same N rate significantly reduced CH4 emissions by 35% (winter spring cropping season) and 32% (summer cropping season) at the rate of 120 kg N ha-1. Average CH4 emission was about 2.1 – 2.2 times higher in summer season as compared in winter spring season. To develop effective GHG mitigation strategies future work is needed to (i) quantify the effects on both CH4 and N2O emissions), (ii) investigate options for combining mitigation practices.