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Further Evidence for the Inability of the Kjeldahl Total Nitrogen Method to Fully Measure Indigenous Fixed Ammonium Nitrogen in Subsoils
Author(s) -
Meints Ver W.,
Peterson Gary A.
Publication year - 1972
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1972.03615995003600030020x
Subject(s) - kjeldahl method , subsoil , nitrogen , ammonium , chemistry , soil water , mathematics , environmental chemistry , zoology , environmental science , soil science , biology , organic chemistry
Three methods of Kjeldahl total N determinations in soils were compared. Method 1 involved a pretreatment of the soil with a HF‐acid mixture and resulted in higher N values than methods 2 or 3 which involved a long period of digestion and a modification of a Gunning method, respectively. Differences in total N values obtained by the three methods were greatest for subsoils. The inability of methods 2 and 3 to measure all of the indigenous fixed NH 4 + ‐N resulted in low N values and erroneously high C:N ratios in the subsoil.