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Extraction and Colorimetric Determination of Urea in Soils
Author(s) -
Douglas L. A.,
Bremner J. M.
Publication year - 1970
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/sssaj1970.03615995003400060015x
Subject(s) - chemistry , urea , urease , sulfuric acid , phosphoric acid , soil water , colorimetry , nitrite , extraction (chemistry) , chromatography , ammonium acetate , distillation , ammonium nitrate , ammonium , nitrate , nuclear chemistry , inorganic chemistry , organic chemistry , high performance liquid chromatography , environmental science , soil science
A simple colorimetric method of determining urea in soils is described. The soil sample is extracted with 2 M KCl containing a urease inhibitor (phenylmercuric acetate), and the extract is analyzed for urea by measurement of the red color formed when an aliquot is heated with diacetyl monoxime and thiosemicarbazide under acidic couditions (phosphoric acid‐sulfuric acid medium). The method is sensitive and precise, and it gives quantitative recovery of urea added to soils. The extraction performed is satisfactory for determination of exchangeable ammonium, nitrite, and nitrate by steam distillation methods.