Studies of nitrogen metabolism in soils with particular reference to the effects of certain trace elements

• Main Author: Premi, Panju Ram
• Published: Imperial College London 1968
• Subjects: 577.57
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.623110

Analytical methods evolved in this study included (1) use of ferrous sulphate for determining nitrate in the microdiffusion method, (2) use of boiling 6N-HC1 for determining total major and trace elements in plant materials and organic residues and (3) use of atomic absorption spectroscopy for determining major and trace elements in extracts used for fractionating these elements in soils and sewage sludge. The first part of the study included work on the metabolism of nitrogen during incubation of soil in relation to moisture content, temperature, pH and addition of organic materials. The effect of levels of applied ammonium sulphate on loss of ammonia by volatilisation and the rate of nitrification were studied in soils of different pH. The comparative utilisation of mineral-N, applied as ammonium or nitrate, by decomposing organic materials was also studied. The main part of the study was concerned with the effects of addition of trace elements (copper and zinc in particular and also chromium and manganese) on ammonification and nitrification during incubation of soils. The trace elements were added as pure salts and also in the form of natural sewage sludge containing these elements as contaminants. In addition studies were also made on mineralisation of nitrogen in samples taken from field soils which had received varying levels of digested sewage sludge over three years. Fractionation of copper and zinc in sewage sludge and peat before and after treatment with copper and zinc salts was studied by the use of various chemical extractants.