title: Ranking factors affecting emissions of GHG from incubated agricultural soils.
abstract: Agriculture significantly contributes to global greenhouse gas (GHG) emissions and there is a need to develop effective mitigation strategies. The efficacy of methods to reduce GHG fluxes from agricultural soils can be affected by a range of interacting management and environmental factors. Uniquely, we used the Taguchi experimental design methodology to rank the relative importance of six factors known to affect the emission of GHG from soil: nitrate (NO3-) addition, carbon quality (labile and non-labile C), soil temperature, water-filled pore space (WFPS) and extent of soil compaction. Grassland soil was incubated in jars where selected factors, considered at two or three amounts within the experimental range, were combined in an orthogonal array to determine the importance and interactions between factors with a L16design, comprising 16 experimental units. Within this L16design, 216 combinations of the full factorial experimental design were represented. Headspace nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) concentrations were measured and used to calculate fluxes. Results found for the relative influence of factors (WFPS and NO3-addition were the main factors affecting N2O fluxes, whilst glucose, NO3-and soil temperature were the main factors affecting CO2and CH4fluxes) were consistent with those already well documented. Interactions between factors were also studied and results showed that factors with little individual influence became more influential in combination. The proposed methodology offers new possibilities for GHG researchers to study interactions between influential factors and address the optimized sets of conditions to reduce GHG emissions in agro-ecosystems, while reducing the number of experimental units required compared with conventional experimental procedures that adjust one variable at a time.
authors.affiliation: Departamento de Química y Análisis Agrícola, Escuela Universitaria de Ingeniería Técnica Agrícola, Universidad Politécnica de Madrid Ciudad Universitaria, 28040, Madrid, Spain.
authors.forename: S
authors.initials: S
authors.lastname: García-Marco
authors.affiliation: Rothamsted Research North Wyke, Okehampton, Devon, EX20 2SB, UK.
authors.forename: S R
authors.initials: SR
authors.lastname: Ravella
authors.affiliation: Rothamsted Research North Wyke, Okehampton, Devon, EX20 2SB, UK.
authors.forename: D
authors.initials: D
authors.lastname: Chadwick
authors.affiliation: Departamento de Química y Análisis Agrícola, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid Ciudad Universitaria, 28040, Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Vallejo
authors.affiliation: Rothamsted Research West Common, Harpenden, Hertfordshire, AL5 2JQ, UK.
authors.forename: A S
authors.initials: AS
authors.lastname: Gregory
authors.affiliation: Rothamsted Research North Wyke, Okehampton, Devon, EX20 2SB, UK.
authors.forename: L M
authors.initials: LM
authors.lastname: Cárdenas