XCVIII.—Experiments on the rate of nitrification

Abstract

By RICHARD MOORE BEESLEY. ALTHOUGH much work has previously been undertaken on the subject of nitrification, i t has, ils a rule, been either of a morphological nature or concerned more especially with the conditions of nitrification of amrnoniuin salts. Munro (T., 1886, 49, 632) showed that solutions of various nitrogen-containing organic substances easily underwent nitrification when inoculated with garden soil, but considering the small number of his isolated analyses and the varying conditions under which his experiments were conducted it is impossible t o obtain from his work any accurate idea of the rate of the nitrification of the substancea he employed. The present work was undertaken with the object of determining the rates of nitrification, and any differences that might exist in these ratea, of dilute solutions of a number of amino-compounds, that is, whether the rate of nitrification was a t all dependent on the complexity of the molecule. I n order to attain this object i t was necessary t o conduct the nitrification of each substance under identically the same conditions, the only variable factor throughout the series being the nitrogenous substance in solution. Dilute solutions of the following compounds were employed : Carbamide, thiocarbamide, uric acid, asparagine, glycine, acetamide, aniline sulphate, methylamine sulphate, ammonium oxalate, and ammonium sulphate. A modified form of the so-called flask method of cultivation was employed, the solutions being made up on the basis of those

Biochemistry of Nitrification in Soil

“…Winogradsky himself pointed out in 1931 (70) that the data concerning the behavior of the nitrifying organisms in pure culture had still to be applied to the development of these bacteria in soil. The optimum temperature for nitrification is dependent on the site of isolation of the organism (64) but in the temperate regions it is approximately 25 C. Nitrification may be observed (13,40,42) over a wide range of pH [5][6][7][8][9][10][11][12][13], but the actual range with an isolated organism seems to be dependent on the pH of the soil from which it was isolated. Nonbiological nitrification has also been discussed (19,50,63).…”

“…There can be no question of the great importance of studies of pure cultures of these organisms, especially for the investigation of intermediate metabolic products which are unstable in presence of a medium such as soil. The occurrence of hyponitrous acid during nitrification, for example, in flask culture has been demonstrated (7,16) but there is as yet no clear evidence of the formation of this substance during nitrification in soil. Hydroxylamine has long been suggested (31) as a potential intermediate in the oxidation of ammonia but no conclusive proof of its presence has been reported.…”

The Nitrogen Cycle in the Sea

“…A small part of this may be photochemically oxidized at the surface but inevitably, failing oxidation, ammonia must accumulate in considerable quantity between, say, 20 and 150 m. The point is capable of experimental test, but at present there is no evidence for such a " hold-up " in the nitrogen cycle in the sea. Beesley (1914) found some evidence for the formation of an intermediary in the bacterial oxidation of ammonia to nitrite, and this has now been identified by Corbet (1935). He pictures the micro-biological oxidation of ammonia as NH 3 -> NH 2 OH -> H 2 N 2 O 2 -> HNO 2 -> HNO 3 , a mechanism in accord with electrochemical views.…”

Biochemistry of nitrification in soil

“…Winogradsky himself pointed out in 1931 (70) that the data concerning the behavior of the nitrifying organisms in pure culture had still to be applied to the development of these bacteria in soil. The optimum temperature for nitrification is dependent on the site of isolation of the organism (64) but in the temperate regions it is approximately 25 C. Nitrification may be observed (13, 40, 42) over a wide range of pH [5][6][7][8][9][10][11][12][13], but the actual range with an isolated organism seems to be dependent on the pH of the soil from which it was isolated. Nonbiological nitrification has also been discussed (19,50,63).…”