Nitrous oxide emissions from organic and conventional crop rotations in five European countries

S. O. Petersen¹, K. Regina², A. Pöllinger³, E. Rigler⁴, L. Valli⁵, S. Yamulki⁶, M. Esala², C. Fabbri⁵, E. Syväsalo² and F. P. Vinther¹

Abstract
Nitrous oxide (N₂O) emissions from agriculture are currently estimated from N inputs using emission factors, and little is known about the importance of regional or management-related differences.

This paper summarizes the results of a study in which N₂O emission rates were recorded on 15–26 occasions during a 12-month period in organic and conventional dairy crop rotations in five European countries (Austria, Denmark, Finland, Italy, UK). A common methodology based on static chambers was used for N₂O flux measurements, and N₂O data were compiled together with information about N inputs (from fertilizers, N₂ fixation, atmospheric deposition and excretal returns), crop rotations and soil properties. Organic rotations received only manure as N fertilizer, while manure accounted for 0–100% of fertilizer N in conventional rotations. A linear regression model was used to examine effects of location, system and crop category on N₂O emissions, while a second model examined effects of soil properties.

Nitrous oxide emissions were higher from conventional than from organic crop rotations except in Austria and, according to the statistical analysis, the differences between locations and crop categories were significant. Ammonium was significantly related to N₂O emissions, although this effect was dominated by observations from a grazing system. Despite the limited number of samplings, annual emissions were estimated by interpolation. Across the two systems and five locations there was a significant relationship between total N inputs and N₂O emissions at the crop rotation level which indicated that annually 1.6 ± 0.2% (mean ± standard error) of total N inputs were lost as N₂O, while there was a background emission of 1.4 ± 0.3 kg N₂O-N ha⁻¹ year⁻¹. Although this measurement program emphasized system effects at the expense of high temporal resolution, the results indicate that N input is a significant determinant for N₂O emissions from agricultural soils.


Source
Agriculture Ecosystems & Environment (2006) 112: 200-206


Author Locations and Affiliations
(1) Danish Institute of Agricultural Sciences, DK-8830 Tjele, Denmark
(2) Agrifood Research Finland (MTT), FIN-31600 Jokioinen, Finland
(3) Federal Research Institute for Agriculture in Alpine Regions (BAL), A-8952 Irdning, Austria
(4) Institute for Landscape Development, Recreation and Conservation Planning (ILEN), University for Agriculture, A-1190 Vienna, Austria
(5) Research Centre for Animal Production (CRPA spa), I-42100 Reggio Emilia, Italy
(6) Institute of Grassland and Environmental Research (IGER), North Wyke, Okehampton EX20 2SB, UK


Posted April 2010