Nitric Oxide and Nitrous Oxide Production from Soil: Water and Oxygen Effects
1992
Drury, C. F. | Findlay, W. I. | McKenney, D. J.
This study was designed to determine the effects of water and O₂ on the speciation of denitrification gases (NO and N₂O). Nitric oxide was found to be the principal end product from soil incubated under low-moisture conditions, whereas the relative amount of N₂O increased under wetter moisture regimes. The total amount of NO plus N₂O produced increased with increasing water content for the Brookston clay loam (fine-loamy, mixed, mesic Typic Argiaguoll), whereas it peaked at 150 g kg⁻¹ (15%) water content with the Fox sandy loam (fine-loamy over sandy or sandy or sandy-skeletal, mixed, mesic, Typic Hapludalf). The decrease in NO plus N₂O at higher water contents was probably the result of the subsequent reduction of N₂O to N₂ in the Fox sandy loam soil. The residence time of the denitrification gases in the soil increased with increasing water content, hence facilitating the subsequent conversions of NO to N₂O and N₂. The thickness of the water film surrounding the microbes affected both the diffusion of O₂ through the water and into the microbes as well as the diffusion of denitrification gases (NO, N₂O, and N₂) from the microbes into the atmosphere. In the sandy loam soil, O₂ content and soil water affected both the amount and species of evolved denitrification gases. Oxygen was more effective in decreasing NO production at lower than at higher water contents.
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