Effect of Soil pH on Emissions of Nitrous Oxide

Keywords: Nitrous oxide, N₂O, soil, nitrogen, soil pH, microbiology.

This paper argues that soil pH should be considered a master variable controlling the nitrous oxide (N₂O) emission from agricultural soils, hence a target for mitigations of N₂O emissions. The first empirical observations of an effect of soil pH on the N₂O/(N₂+N₂O) product ratio of denitrification were made 60 years ago, but the mechanism involved was not understood. Recent investigations have shown that the N₂O/(N₂+N₂O) product ratio of denitrification is pervasively controlled by soil pH, and that the main reason is that low pH interferes with the making of the enzyme N₂O reductase at a post transcriptional level. Harnessed with a better understanding of the mechanism, we should be able to deliberately use pH management as an effective method to reduce N₂O emissions from cultivated soils.

Lars R Bakken, Department of Environmental Sciences, Norwegian University of Life Science, Fougner Bakken 3, NO-1430 Ã…s, Norway.

14 pages, 3 figures, 21 references.