Premium
Modeling and Field Measurements of the Effect of Nitrogen Source on Nitrification
Author(s) -
McInnes K. J.,
Fillery I.R.P.
Publication year - 1989
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/sssaj1989.03615995005300040045x
Subject(s) - nitrification , chemistry , urea , ammonium , alkalinity , nitrogen , diammonium phosphate , leaching (pedology) , environmental chemistry , ammonium sulfate , incubation , nitrifying bacteria , zoology , soil science , environmental science , soil water , chromatography , biochemistry , biology , organic chemistry
The movement of N in relation to water movement and plant uptake is, in part, determined by the rate of nitrification. Nitrifying bacteria are known to be inhibited by low pH. A laboratory incubation and a field experiment were conducted to study nitrification of NH 4 supplied by ammonium sulfate (AS), diammonium phosphate (DAP), and urea, N sources that produce environments with different pH, particularly when applied to moderately acidic, poorly pH‐buffered soil. The field site was located on a texture contrast soil (sandy, thermic Natric Durixeralf) at Merredin, Western Australia. The incubations were performed on a sample of the surface 100 mm of this soil. The initial pH and the pH‐buffer capacity of the sample were 5.4 and 4 mmol kg −1 (pH unit) −1 , respectively. Nitrification rates were found to vary with the inherent alkalinity of the N source, viz., urea > DAP > AS. The nitrification process was modeled taking into account the effect of pH on nitrifier growth and activity. A linear relation in the model between pH, and both the specific growth rate and activity of the nitrifiers accounted for most of the variability between N sources. In the field experiment, 15 N remained largely in nonnitrate form for the first month after application, presumably because of low temperatures, but after 53 d production of NO 3 was greater with urea than AS. With the slow rate of nitrification, the leaching of NO 3 was minimal.