Open AccessNitrification exhibits Haldane kinetics in an agricultural soil treated with ammonium sulfate or dairy‐waste compost
Author(s) -
Koper Teresa E.,
Stark John M.,
Habteselassie Mussie Y.,
Norton Jeanette M.
Publication year - 2010
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2010.00960.x
Subject(s) - nitrification , compost , ammonium , soil water , fertilizer , zoology , ammonium sulfate , environmental chemistry , agronomy , biology , environmental engineering , chemistry , nitrogen , ecology , environmental science , chromatography , organic chemistry
An agricultural soil was treated with dairy‐waste compost, ammonium‐sulfate fertilizer or no added nitrogen (control) and planted to silage corn for 6 years. The kinetics of nitrification were detemined in laboratory‐shaken slurry assays with a range of substrate concentrations (0–20 mM NH 4 + ) over a 24‐h period for soils from the three treatments. Determined concentrations of substrate and product were fit to Michaelis–Menten and Haldane models. For all the treatments, the Haldane model was a better fit, suggesting that significant nitrification inhibition may occur in soils under high ammonium conditions similar to those found immediately after fertilization or waste applications. The maximum rate of nitrification ( V max ) was significantly higher for the fertilized and compost‐treated soils (1.74 and 1.50 mmol N kg −1 soil day −1 ) vs. control soil (0.98 mmol kg −1 soil day −1 ). The K m and K i values were not significantly different, with average values of 0.02 and 27 mM NH 4 + , respectively. Our results suggest that both N sources increased nitrifier community size, but did not shift the nitrifier community structure in ways that influenced enzyme affinity or sensitivity to ammonium. The K m values are comparable to those determined directly in other soils, but are substantially lower than those from most pure cultures of ammonia‐oxidizing bacteria.