Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.641190
Title: Nitrous oxide emissions from incorporated crop residues and green manures
Author: Baggs, E.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1997
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Abstract:
A series of field and laboratory experiments were undertaken to examine the effects of incorporation of plant material on emissions of N2O from agricultural soils. The overall aim was to increase understanding of that part of the agricultural N cycle, associated with the release of N after incorporation of crop residues and green manures into soil, and subsequent N2O emissions to the atmosphere. N2O emissions from growing corps and following addition of various residues and green manures to soil were measured and compared. The effects of crop type, fertiliser application, cultivation techniques, soil type, and climatic conditions, and also of the addition of high C substrate in the form of paper waste, on these emissions were investigated. Emissions of N2O were increased after cultivation of soil, attributed to increased accessibility of organic matters to soil microbes, and improved gaseous diffusion. Emissions were higher following incorporation of plant material than emissions from bare soil. Generally, fluxes were increased within a few hours or days after cultivation and/or incorporation, but the effect was short-lived. Most of the N2O was emitted during the first 2 weeks. The magnitude and timing of N2O released within this period was highly dependent on temperature and rainfall following incorporation, and the cultivation technique employed. The C:N ratio of the incorporated plant material had a considerable effect on rates of decomposition, and on subsequent N2O production during nitrification and denitrification. Higher emissions were typically measured after incorporation of material with a low C:N ratio, such as legumes, than when material with higher ratios, such as cereal straw, was involved. When material with a high C:N ratio was added, N was immobilised. Nevertheless, the presence of high C:N paper waste increased N2O emissions from incorporated vegetable crop residues. This was attributed to the creation of more anaerobic sites in the soil. Emissions of N2O increased within a few days of applying mineral N fertiliser to spring-sown cereal crops. Again, these fluxes were short-lived. Use of 15N-labelling in this experiment showed that approximately 50% of crop N at harvest was derived from applied fertiliser. In other experiments, the presence of a growing crop particularly a legume, increased emissions, compared with those measured from bare soil. The measurements of soil mineral N (the substrate for N2O) were compared with the amounts predicted by various N models. Practical suggestions were made for ways to lower N2O emissions from agricultural systems, thereby reducing detrimental effects on the ozone layer and global warming.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.641190  DOI: Not available
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