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The Ammonia in Soils

Published online by Cambridge University Press:  27 March 2009

Edward John Russell
Affiliation:
“Goldsmith” Soil Chemist, Rothamsted Experiment Station.

Extract

It has long been recognised that the amount of ammonia in soils cannot be determined by distillation with a solution of caustic soda or potash since these strong alkalis slowly decompose the complex nitrogenous matter and evolve a coutinuous stream of ammonia. Boussingault showed more than fifty years ago how this difficulty could be obviated. By using magnesia in place of soda or potash the decomposition of such substances as urea, asparagin, and albumin was not great even on long boiling, but when the distillation was carried out under reduced pressure at 38°—40° there was no decomposition at all. Ammonium salts, on the other hand, were completely broken up in these circumstances. He used this low pressure method in his researches on the ammonia content of urine, but does not appear to have applied it to soils. Sufficiently accurate results could, he considered, be obtained by distillation at 100°, and this method was for many years generally adopted. It gave results varying according to the nature of the soil from 10 to 100 parts of nitrogen per million (·001 to ·01 per cent.), which may still be found quoted in some of the agricultural text books.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1910

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References

Page 233 note 1 “Da dosage de l’ammoniaque en présence des substances organiques azotées,” Agronomie, 1864, III. 206.Google Scholar

Page 233 note 2 “Recherches sur la quantité d’ammoniaque contenue dans l’urine,” ibid. p. 233. Lime was used in these experiments in place of magnesia.

Page 233 note 3 Grandeau, , Analyse des Matières Agricoles, 1879Google Scholar

Page 234 note 1 Annales de Chim. et de Phys. [VI] XXV. 327.Google Scholar

Page 234 note 2 Chem, . Centralblatt, 1860, pp. 243 and 534.Google Scholar

Page 234 note 3 Landw. Versuchs-Stationen, 1886, 33, 247.Google Scholar

Page 243 note 1 Three-quarters of the dressing was applied on April 7th, the other quarter having been put on on the previous Oct. 7 and 8.

Page 244 note 1 Stevens, Withers, Temple and Syme have recently examined a number of soils by both methods and find no sort of agreement in the results (Centr. filr Bakt. Abt. II. 1909, 23, 355).

Page 244 note 2 This vol. p. 111.