How to minimize the methane flux from agricultural fields?
Answers
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
) 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.