Methane consumption under the influence of different nitrogen sources in a tropical soil ecosystem

In order to minimize methane (CH₄) concentration in the atmosphere we need to better understand CH₄ consumption in agricultural soils. Nitrogen application to agriculture is predicted to increase significantly in the coming years to meet food security needs. However, the interaction between soil nitrogen and CH₄ consumption is poorly understood. Experiments were carried out to evaluate CH₄ consumption under the influence of the three nitrogen sources comprising N₂(at ambient+5% and ambient+10%),NO₃-N (at 10 mM and 20 mM) and NH₄-N (at 10 mM and 20 mM). CH₄ consumption was evaluated at different CH₄ concentrations and feeding cycles to validate the effect of nitrogen. Among different N sources, N₂ stimulated CH₄ consumption potential by about 1.11–1.71 times over that in the absence of additional nitrogen (control), while N in the form of both NO₃ and NH₄ inhibited CH₄ consumption by 1.14–2.18 times than in the control. CH₄ consumption rate increased with CH₄ feeding cycles. The effect of N sources on CH₄ consumption followed similar trends irrespective of the N rate added.N₂ stimulated the abundance of both nifH and pmoA genes. Abundance of methanotrophs pmoA gene copies and nitrifiers amoA gene copies were more in NH₄-Namended soil than NO₃-N.Available NO₃ content in soil increased 9–30% with CH₄ driven N₂ fixation. This study concludes that N₂ stimulated CH₄ consumption while nitrogen in the form of NO₃ and NH₄ inhibited CH₄ consumption in a tropical vertisol.