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Nitrification Responses of Soil Ammonia‐Oxidizing Archaea and Bacteria to Ammonium Concentrations
Author(s) -
Giguere Andrew T.,
Taylor Anne E.,
Myrold David D.,
Bottomley Peter J.
Publication year - 2015
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/sssaj2015.03.0107
Subject(s) - nitrification , soil water , ammonium , chemistry , agronomy , microcosm , soil ph , environmental chemistry , environmental science , nitrogen , soil science , biology , organic chemistry
Although ammonia‐oxidizing archaea (AOA) and bacteria (AOB) coexist in most non‐acidic agricultural soils, the factors that influence their relative contributions to soil nitrification activity remain unclear. A 2‐ to 4‐d whole soil microcosm assay was developed, utilizing the aliphatic C 8 alkyne 1‐octyne to inactivate AOB‐driven nitrification activity without impacting AOA nitrification activity. Responses of AOA‐ and AOB‐supported net nitrification activities (accumulation of NO 2 − + NO 3 − ) to different concentrations of extractable NH 4 + were examined in four diverse, paired cropped and non‐cropped Oregon soils sampled in summer and winter. Maximum AOA‐supported net nitrification rates were significantly higher in non‐cropped (3.7 mg N kg −1 soil d −1 ) than in cropped soils (0.9 mg N kg −1 soil d −1 ) and in summer (3.1 mg N kg −1 soil d −1 ) compared with winter soils (1.6 mg N kg −1 soil d −1 ). The NH 4 + concentration required to significantly stimulate AOB nitrification activity was significantly higher in cropped soils (67 mg N kg −1 soil) than in non‐cropped soils (12 mg N kg −1 soil). Maximum AOB activity was significantly higher in cropped (8.6 mg N kg −1 soil d −1 ) than in non‐cropped soils (2.9 mg N kg −1 soil d −1 ) and in summer (7.8 mg N kg −1 soil d −1 ) compared with winter soils (3.8 mg N kg −1 soil d −1 ). This study revealed that AOA‐ and AOB‐supported nitrification rates in cropped and non‐cropped soils respond differently to season and NH 4 + concentration and raises the possibility that AOA and AOB nitrification activities might be differentially managed to improve N use efficiency.