Algal nitrogen fixation on solid surfaces and temperate agricultural soils

2.50
Hdl Handle:
http://hdl.handle.net/10547/559515
Title:
Algal nitrogen fixation on solid surfaces and temperate agricultural soils
Authors:
Featherstone-Witty, John
Abstract:
This thesis examines various factors controlling algal nitrogen fixation and nitrogen release in temperate agricultural soils. New apparatus for investigating nitrogenase activity on uniform soil grown algal crusts and for the in.situ estimation of nitrogen fixation in the field is described. The effects of oxygen concentration and temperature on acetylene reduction by soil grown cultures of Nostoc ellipsosporum in the light and in the dark suggest that ATP generated by oxidative phosphorylation contributes to fixation even in the light. The oxygen concentration giving optimum nitrogenase activity depends on the intensity of illumination, largely because of the continuing contribution from dark fixation. The oxygen dependent acetylene reduction continued throughout the night in the field at 20% of the midday rate. This proportion is dependent on daytime light intensity and day/night temperature drop. The release of nitrogenous compounds by soil and sand grown cultures of N .ellipsosporum was investigated in the laboratory. Algal cultures growing on sand released only 20/0. of the total nitrogen compared with 10% released by liquid cultures. Freezing to below -30C, drying to less than 4% moisture or pathogenic infection all cause extensive cellular lysis with a concomitant loss of nitrogenase activity, followed, after several days, by a surge in ammonia concentration. The recovery of nitrogenase activity after re-wetting was investigated in the field after a period of dry weather. All samples achieved a steady rate of nitrogenase activity after 400 minutes irrespective of the magnitude of recovery. Nitrogenase activity in the field was monitored at weekly intervals using an in situ technique over a two year period on Broadbank, one of the Rothamsted classic plots sown to winter wheat. The seasonal fixation rates varied from 1.4 to 28 Kg/ha depending on the fertilizer and herbicide treatment. The greatest seasonal fixation was given by non-herbicide plots receiving 48 Kg N/ha of applied nitrogen. The effect of various species of algal inoculum was investigated on 60 plots sown to winter wheat with and without irrigation and added nitrogen. A significant increase in fixation was produced and the most effective treatment was a liquid application of N. ellipsosporum. Both the N. punctiforme and Anabaena cylindrica were more effective when applied as dried sand cultures. The most important single factor limiting algal development in field experiments was soil moisture.
Citation:
Featherstone-Witty, J. (1974) 'Algal nitrogen fixation on solid surfaces and temperate agricultural soils'. PhD thesis. Luton College of Technology and Bedford College, University of London.
Publisher:
University of Bedfordshire
Issue Date:
Sep-1974
URI:
http://hdl.handle.net/10547/559515
Type:
Thesis or dissertation
Language:
en
Description:
A thesis presented by JOHN FEATHERSTONE-WITTY for the Degree of Doctor of Philosophy in the Faculty of Science of the University of London
Appears in Collections:
PhD e-theses

Full metadata record

DC FieldValue Language
dc.contributor.authorFeatherstone-Witty, Johnen
dc.date.accessioned2015-07-10T11:15:45Zen
dc.date.available2015-07-10T11:15:45Zen
dc.date.issued1974-09en
dc.identifier.citationFeatherstone-Witty, J. (1974) 'Algal nitrogen fixation on solid surfaces and temperate agricultural soils'. PhD thesis. Luton College of Technology and Bedford College, University of London.en
dc.identifier.urihttp://hdl.handle.net/10547/559515en
dc.descriptionA thesis presented by JOHN FEATHERSTONE-WITTY for the Degree of Doctor of Philosophy in the Faculty of Science of the University of Londonen
dc.description.abstractThis thesis examines various factors controlling algal nitrogen fixation and nitrogen release in temperate agricultural soils. New apparatus for investigating nitrogenase activity on uniform soil grown algal crusts and for the in.situ estimation of nitrogen fixation in the field is described. The effects of oxygen concentration and temperature on acetylene reduction by soil grown cultures of Nostoc ellipsosporum in the light and in the dark suggest that ATP generated by oxidative phosphorylation contributes to fixation even in the light. The oxygen concentration giving optimum nitrogenase activity depends on the intensity of illumination, largely because of the continuing contribution from dark fixation. The oxygen dependent acetylene reduction continued throughout the night in the field at 20% of the midday rate. This proportion is dependent on daytime light intensity and day/night temperature drop. The release of nitrogenous compounds by soil and sand grown cultures of N .ellipsosporum was investigated in the laboratory. Algal cultures growing on sand released only 20/0. of the total nitrogen compared with 10% released by liquid cultures. Freezing to below -30C, drying to less than 4% moisture or pathogenic infection all cause extensive cellular lysis with a concomitant loss of nitrogenase activity, followed, after several days, by a surge in ammonia concentration. The recovery of nitrogenase activity after re-wetting was investigated in the field after a period of dry weather. All samples achieved a steady rate of nitrogenase activity after 400 minutes irrespective of the magnitude of recovery. Nitrogenase activity in the field was monitored at weekly intervals using an in situ technique over a two year period on Broadbank, one of the Rothamsted classic plots sown to winter wheat. The seasonal fixation rates varied from 1.4 to 28 Kg/ha depending on the fertilizer and herbicide treatment. The greatest seasonal fixation was given by non-herbicide plots receiving 48 Kg N/ha of applied nitrogen. The effect of various species of algal inoculum was investigated on 60 plots sown to winter wheat with and without irrigation and added nitrogen. A significant increase in fixation was produced and the most effective treatment was a liquid application of N. ellipsosporum. Both the N. punctiforme and Anabaena cylindrica were more effective when applied as dried sand cultures. The most important single factor limiting algal development in field experiments was soil moisture.en
dc.language.isoenen
dc.publisherUniversity of Bedfordshireen
dc.subjectC240 Plant Cell Scienceen
dc.subjectalgal nitrogen fixationen
dc.subjectnitrogen releaseen
dc.titleAlgal nitrogen fixation on solid surfaces and temperate agricultural soilsen
dc.typeThesis or dissertationen
dc.type.qualificationnamePhDen_GB
dc.type.qualificationlevelPhDen
dc.publisher.institutionUniversity of Bedfordshireen
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