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Nitrate Reduction and Nitrite Utilization by Nitrifiers in an Unsaturated Hanford Sandy Loam
Author(s) -
Volz M. G.,
Belser L. W.,
Ardakani M. S.,
McLaren A. D.
Publication year - 1975
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1975.00472425000400020008x
Subject(s) - nitrate , loam , nitrite , chemistry , ammonium , environmental chemistry , denitrification , nitrification , anoxic waters , nitrous oxide , nitrogen , nitrous acid , soil water , zoology , inorganic chemistry , ecology , biology , organic chemistry
In order to discern any relationship between added nitrate and microbial growth in a field plot, a Hanford sandy loam was infiltrated for 5 weeks at a rate of 5 cm day −1 with a solution containing 100 ppm ‐N and 1.25 meq/liter Cl − as KNO 3 and CaCl 2 respectively. Nitrate‐N, NO 2 − ‐N and Cl − concentrations in soil solution were determined and corresponding counts of nitrate reducers, denitrifiers, and NH 4 + ‐ and NO 2 − ‐oxidizer populations were made. Ratios of measured to applied concentrations for both NO 3 − ‐N and Cl − were nearly identical in all solution samples taken from the unsaturated soil profile, i.e., nitrate reduction was not pronounced and NO 2 − ‐N was less than 1 ppm. Nitrate reducer populations (6x10 4 –6x10 5 /g soil) were always larger than those of denitrifiers (3x10 3 –3x10 4 /g) and varied little with time and depth. Ammonium oxidizers (10 1 –10 5 /g) generally decreased with depth. In contrast, NO 2 − oxidizers (10 1 –3x10 6 /g) varied markedly with time at all depths. An increase in numbers of NO 2 − oxidizers, after 2 to 3 weeks, at a depth of 60 cm, is attributed to NO 2 − produced by reduction of NO 3 − at anoxic microsites within the profile. Evidently, a cyclic oxidation and reduction of nitrite and nitrate, occurring simultaneously, is responsible for growth of nitrite oxidizers in the profile.