Atmospheric Environment, Feb, 2012, Vol.47, p.373(8)
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.atmosenv.2011.10.052 Byline: David Fangueiro (a), Joao Coutinho (b), Fernanda Cabral (a), Paula Fidalgo (b), Roland Bol (c), Henrique Trindade (d) Abstract: The application to soil of different slurry particle size fractions may lead to variable gaseous soil emissions and associated differential environmental impacts. An incubation experiment was carried out during 70 d to assess the influence on nitric oxide (NO) and greenhouse gas (GHG; i.e. nitrous oxide, carbon dioxide and methane) emissions following incorporation of 4 particle size fractions, obtained through laboratorial separation from cattle slurry, to agricultural sandy loam soil (Dystric Cambisol). The response to these applied slurry fractions (〉2000 [mu]m, 2000-500 [mu]m, 500-100 [mu]m, 〈100 [mu]m) was compared to other experimental treatments, including whole slurry (WS), ammonium sulphate (AS) and an unamended control (CON). The highest value of cumulated NO emissions (6.3 mg NO-N kg.sup.-1 dry soil) were observed from the AS treatment. The cumulated amount of NO emitted ([approximately equal to]1 mg NO-N kg.sup.-1 dry soil) was not significantly different between slurry fractions, thereby indicating that slurry particle size had no effect on NO emissions. The largest slurry fraction (〉2000 [mu]m) induced significantly higher N.sub.2O emissions (1.8 mg N.sub.2O-N kg.sup.-1 dry soil) compared to the other smaller sized fractions (1.0 mg N.sub.2O-N kg.sup.-1 dry soil). The 〉2000 [mu]m, fraction, being more than 55% of the slurry by weight, was the major contributor to daily and cumulative N.sub.2O emissions. Hence, for N.sub.2O, the application of WS to agricultural soil is a better option that amendment with the 〉2000 [mu]m, fraction. Low CH.sub.4 emissions (〈200 [mu]g CH.sub.4-C kg.sup.-1 dry soil d.sup.-1) were observed, but only in treatments amended with slurry or its fractions. The CH.sub.4 emissions were short-lived and rates returned to control levels within 3 d after the slurry application. Higher CO.sub.2 emissions were observed in soils amended with slurry fractions when compared to application with whole slurry. Clearly, slurry separation can increase soil CO.sub.2 emissions relative to whole slurry application. Overall, N.sub.2O contributed 10-30% to total GHG emissions, while that of methane was negligible. The present study suggested that mechanical separation of slurry into fractions and targeted application of the finest fractions to soil is a potential suitable management tool to reduce GHG emissions. However, the largest fractions have to be used for other purposes as anaerobic digestion rather than applied to soil. Author Affiliation: (a) UIQA- Instituto Superior de Agronomia, TU Lisbon, Tapada da Ajuda, 1349-017 Lisboa, Portugal (b) Chemistry Centre, Department of Soil Science, Universidade de Tras-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real, Portugal (c) Sustainable Soils and Grassland Systems Department, Rothamsted Research North Wyke, Devon, EX20 2SB, UK (d) CITAB - Centre for the Research and Technology of Agro-Environment and Biological Sciences, Department of Agronomy, Universidade de Tras-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal Article History: Received 29 June 2011; Revised 19 October 2011; Accepted 24 October 2011
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