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Nitrous oxide emissions from agricultural soils, and the potential for their reduction - CC0233

The aim of this study will be to examine different methods (both physical and chemical) for reducing nitrous oxide (N2O) emissions from agricultural land. The study will be composed of 5 specific objectives outlined as follows, together with ways in which they might be achieved: 1. Measurement of N2O emissions from grass and arable agricultural land using ammonium nitrate as fertiliser. Sites will be established to provide a representative cross-section of soils/climates across the UK. At least 2 intensive grassland and 1 arable site will be established in England or Wales, and a grazed grassland site will be established in Scotland in each of the 3 years of the project. A long-term reference ungrazed grassland site will also be monitored. N2O fluxes will be measured by the closed chamber method with gas chromatographic analysis, while soil water-filled pore space (WFPS), soil temperature and soil mineral N content will be measured concurrently to provide data for modelling. Rainfall data will also be obtained. Measurements will be performed with manual chambers at daily intervals immediately after application of fertiliser and at longer intervals once fluxes subside. Automatic chambers will also be used to monitor short-lived emissions. Results will be expressed as annual emissions of N2O and emissions as a fraction of the fertiliser N applied, and the relationship between fluxes and driving variables will be modelled; 2. Examination of the effect on emissions over the season of incorporating a nitrification inhibitor into an ammonium-based N fertiliser, using a controlled-release form of N, applying urea and a urease inhibitor, and combining urease and nitrification inhibitor treatments in order to delay ammonium formation and prevent its oxidation. Results will be compared with those obtained using ammonium nitrate, an ammonium-based N fertiliser and urea in the absence of urease inhibitor; 3. Examination of the relationship between WFPS, water table depth, matric potential and N2O emission using transects on an existing system of drained plots under grass. Data will be used to model the effects of drainage schemes with different designs on the number of days when the water table is less than 20, 30 or 40 cm from the surface; 4. Evaluation of the relative cost-effectiveness of reducing emissions by modification of fertiliser type and/or using inhibitors compared with physical modification of soils by installation of additional drainage schemes. The potential changes in total emissions from each treatment will be calculated together with their costs; and 5. Publication of results and conclusions in annual and final reports.
Project Documents
• Executive Summary : Nitrous oxide emissions from agricultural soils, and the potential for their reduction   (250k)
Time-Scale and Cost
From: 1999

To: 2001

Cost: £308,587
Contractor / Funded Organisations
University - Edinburgh
Climate Change              
Environmental Protection              
Fields of Study
Agriculture and Climate Change