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Evidence that fungi can oxidize NH4+ to NO3− in a grassland soil.
- Source :
- European Journal of Soil Science; Apr2008, Vol. 59 Issue 2, p285-291, 7p, 1 Diagram, 3 Charts, 1 Graph
- Publication Year :
- 2008
-
Abstract
- The contribution of bacteria and fungi to NH<subscript>4</subscript><superscript>+</superscript> and organic N (N<subscript>org</subscript>) oxidation was determined in a grassland soil (pH 6.3) by using the general bacterial inhibitor streptomycin or the fungal inhibitor cycloheximide in a laboratory incubation study at 20°C. Each inhibitor was applied at a rate of 3 mg g<superscript>−1</superscript> oven-dry soil. The size and enrichment of the mineral N pools from differentially (NH<subscript>4</subscript><superscript>15</superscript>NO<subscript>3</subscript> and <superscript>15</superscript>NH<subscript>4</subscript>NO<subscript>3</subscript>) and doubly labelled (<superscript>15</superscript>NH<subscript>4</subscript><superscript>15</superscript>NO<subscript>3</subscript>) NH<subscript>4</subscript>NO<subscript>3</subscript> were measured at 3, 6, 12, 24, 48, 72, 96 and 120 hours after N addition. Labelled N was applied to each treatment, to supply NH<subscript>4</subscript><superscript>+</superscript>-N and NO<subscript>3</subscript><superscript>−</superscript>-N at 3.15 μmol N g<superscript>−1</superscript> oven-dry soil. The N treatments were enriched to 60 atom % excess in <superscript>15</superscript>N and acetate was added at 100 μmol C g<superscript>−1</superscript> oven-dry soil, to provide a readily available carbon source. The oxidation rates of NH<subscript>4</subscript><superscript>+</superscript> and N<subscript>org</subscript> were analysed separately for each inhibitor treatment with a <superscript>15</superscript>N tracing model. In the absence of inhibitors, the rates of NH<subscript>4</subscript><superscript>+</superscript> oxidation and organic N oxidation were 0.0045 μmol N g<superscript>−1</superscript> hour<superscript>−1</superscript> and 0.0023 μmol N g<superscript>−1</superscript> hour<superscript>−1</superscript>, respectively. Streptomycin had no effect on nitrification but cycloheximide inhibited the oxidation of NH<subscript>4</subscript><superscript>+</superscript> by 89% and the oxidation of organic N by more than 30%. The current study provides evidence to suggest that nitrification in grassland soil is carried out by fungi and that they can simultaneously oxidize NH<subscript>4</subscript><superscript>+</superscript> and organic N. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 13510754
- Volume :
- 59
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- European Journal of Soil Science
- Publication Type :
- Academic Journal
- Accession number :
- 31166728
- Full Text :
- https://doi.org/10.1111/j.1365-2389.2007.00995.x