Studies on the Measurement of Extractable and Mineralizable Nitrogen in Soil

Qasim Khan, Mohammad (1987) Studies on the Measurement of Extractable and Mineralizable Nitrogen in Soil. PhD thesis, University of Glasgow.

Abstract

The different potassium salts which are used for the extraction of inorganic nitrogen from soils contain variable and often high amounts of ammonium and nitrate nitrogen which could introduce an error in the analysis of low levels of soil inorganic nitrogen. The potassium salt solutions can be purified of ammonium nitrogen by increasing the pH to 11.0 with a solution of potassium hydroxide and then boiling and stirring for 15 minutes. The pH is then readjusted to pH 5.5 - 6.0 with a dilute acid. There is no simple method for the removal of nitrate nitrogen and therefore, it is suggested that a batch number with low nitrate nitrogen content be used for the extraction of soil. Different grades and batches of filter papers also contain variable amounts of ammonium and nitrate nitrogen which needs removing before use for the filtration of soil extracts. Ammonium and nitrate nitrogen can be removed from the filter papers by washing with 50 cm of 0.5 M potassium sulphate in 2 lots each of 25 cm3 , then rinsing twice with deionised water and drying for 4 hours at 70

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Soil sciences
• Date of Award: 1987
• Depositing User: Enlighten Team
• Unique ID: glathesis:1987-77511
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 Jan 2020 11:53
• Last Modified: 14 Jan 2020 11:53
• URI: https://theses.gla.ac.uk/id/eprint/77511