Effects of Phenolic Compounds on Nitrification in Soil1
- G. W. McCarty and
- J. M. Bremner2
Recent literature reflects considerable interest in the hypothesis that climax vegetation inhibits nitrification in soil and that this is due to the production in such vegetation of phenolic compounds that inhibit oxidation of NH+4 by nitrifying microorganisms. This hypothesis is based largely on the detection of tannins and phenolic acids in climax vegetation and in soil under such vegetation and on a report that very small amounts of these phenolic compounds completely inhibited NO-2 production in an aqueous suspension of soil treated with (NH4)2SO4 and a nutrient solution suitable for growth of Nitrosomonas. To test the validity of this hypothesis, we studied the effects of different amounts of eight phenolic acids (p-hydroxy-benzoic acid, p-coumaric acid, vanillic acid, ferulic acid, caffeic acid, ellagic acid, gallic acid, and chlorogenic acid) and five tannins [mangrove (Rhizophora mangle), quebracho (Quebrachia lorentzii), mimosa (Albizia julibrissin), chestnut (Castanea dentata), and sumac (Rhus coriaria)] on nitrification in soils incubated at 30°C after treatment with (NH4)2SO4. These studies provided no support for the hypothesis that climax vegetation inhibits nitrification in soil by producing phenolic compounds because they showed that phenolic acids and tannins did not significantly affect nitrification in soil even when the amounts applied greatly exceeded the amounts that have been reported to inhibit nitrification or to occur in soil.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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